In this study, a lab-scale upflow anaerobic sludge blanket(UASB) reactor was applied to studying the high-rate nitrogen removal of granule-based anammox process. The nitrogen removal rate(NRR) finally improved to 15.7...In this study, a lab-scale upflow anaerobic sludge blanket(UASB) reactor was applied to studying the high-rate nitrogen removal of granule-based anammox process. The nitrogen removal rate(NRR) finally improved to 15.77 kg/m3/d by shortening hydraulic retention time(HRT) to 1.06 h. Well-shaped red anammox granules were extensively enriched inside the reactor. The results of nitrogen removal kinetics indicated that the present bioreactor has great nitrogen removal potential, because the maximum rate of substrate utilization(Umax) predicted by Stover-Kincannon model is suggested as 55.68 kg/(m3·d). Analysis of the microbial community showed that the anammox genus Candidatus Kuenenia dominated the bacterial communities. The relative abundance of Candidatus Kuenenia rose from 12.29% to 36.95% after progressively shorter HRT and higher influent substrate concentrations, illustrating the stability of nitrogen removal performance and biomass enrichment offered by the UASB in carrying out high-rate anammox process.展开更多
Rice seedling blight,caused by various fungi,including Fusarium oxysporum,poses a severe threat to rice production.As awareness grows regarding the environmental and safety hazards associated with the application of f...Rice seedling blight,caused by various fungi,including Fusarium oxysporum,poses a severe threat to rice production.As awareness grows regarding the environmental and safety hazards associated with the application of fungicides for managing rice seedling blight,there has been a shift in focus towards biological control agents.In this study,we isolated biocontrol bacteria from paddy fields that significantly inhibited the growth of F.oxysporum in vitro and identified the strains as Bacillus amyloliquefaciens T40 and Bacillus pumilus T208.Additionally,our findings indicated that the combined application of these Bacillus strains in soil was more effective in reducing the incidence of rice seedling blight than their individual use.Analysis of 16S and internal transcribed spacer rRNA gene sequencing data revealed that the mixture of the T40 and T208 strains exhibited the lowest average clustering coefficients,which were negatively correlated with the biomass of F.oxysporum-inoculated rice seedlings.Furthermore,this mixture led to higher stochastic assembly(average|βNTI|<2)and reduced selection pressures on rice rhizosphere bacteria compared with individual strain applications.The mixture of the T40 and T208 strains also significantly increased the expression of defense-related genes.In conclusion,the mixture of the T40 and T208 strains effectively modulates microbial community structures,enhances microbial network stability,and boosts the resistance against rice seedling blight.Our study supports the development and utilization of biological resources for crop protection.展开更多
Global climate change exerts profound effects on snow cover,with consequential impacts on microbial activities and the stability of soil organic carbon(SOC)within aggregates.Northern peatlands are significant carbon r...Global climate change exerts profound effects on snow cover,with consequential impacts on microbial activities and the stability of soil organic carbon(SOC)within aggregates.Northern peatlands are significant carbon reservoirs,playing a critical role in mitigating climate change.However,the effects of snow variations on microbial-mediated SOC stability within aggregates in peatlands remain inadequately understood.Here,an in-situ field experiment manipulating snow conditions(i.e.,snow removal and snow cover)was conducted to investigate how snow variations affect soil microbial community and the associated SOC stability within soil aggregates(>2,0.25-2,and<0.25 mm)in a peatland of Northeast China.The results showed that snow removal significantly increased the SOC content and stability within aggregates.Compared to the soils with snow cover,snow removal resulted in decreased soil average temperatures in the topsoil(0-30 cm depth)and subsoil(30-60 cm depth)(by 1.48 and 1.34°C,respectively)and increased freeze-thaw cycles(by 11 cycles),consequently decreasing the stability of aggregates in the topsoil and subsoil(by 23.68%and 6.85%,respectively).Furthermore,more recalcitrant carbon and enhanced SOC stability were present in microaggregates(<0.25 mm)at two soil depths.Moreover,reductions in bacterial diversity and network stability were observed in response to snow removal.Structural equation modeling analysis demonstrated that snow removal indirectly promoted(P<0.01)SOC stability by regulating carbon to nitrogen(C:N)ratio within aggregates.Overall,our study suggested that microaggregate protection and an appropriate C:N ratio enhanced carbon sequestration in response to climate change.展开更多
[Objectives]This study was conducted to investigate the influence mechanisms of microbial succession in raw milk under cold storage at different temperatures.[Methods]A raw milk sample was collected from a local large...[Objectives]This study was conducted to investigate the influence mechanisms of microbial succession in raw milk under cold storage at different temperatures.[Methods]A raw milk sample was collected from a local large-scale farm in Tangshan and divided into four treatment gradients:a control group(M)rapidly frozen at-80℃,and three experimental groups stored at 4℃(T),6℃(F),and 8℃(Y),respectively.A time series experiment was carried out according to time intervals of 24,48 and 72 h in each experimental group.Traditional microbial culture methods and 16S rRNA high-throughput sequencing were combined to analyze the dynamic changes in microbial abundance and structural variation.[Results]Plate counting revealed significantly lower total bacterial count and psychrotrophic bacteria in the 4℃storage group within 24 h compared with other treatment groups(P<0.01),confirming that maintaining low-temperature cold chain integrity and controlling treatment time(<24 h)can effectively inhibit microbial metabolic activity.16S rRNA sequencing analysis revealed high initial microbial diversity in raw milk,with dominant genera being Lactococcus,Acinetobacter,and Pseudomonas.Low-temperature treatment effectively reduced theαdiversity index of the microbial community.During the later stage of cold storage at 4℃,the relative abundance of Pseudomonas increased to over 90%,making it the dominant bacterial genus.[Conclusions]This study has significant application value for maintaining the quality of milk and dairy products and prolonging their shelf life.展开更多
The organic matter inmunicipal wastewater can be recovered by anaerobic biological treatment,making further resource utilization of municipal wastewater,which meets the requirements of sustainable development.An upflo...The organic matter inmunicipal wastewater can be recovered by anaerobic biological treatment,making further resource utilization of municipal wastewater,which meets the requirements of sustainable development.An upflow anaerobic biofilter(UAF)treating municipal wastewater was established.The performances of stable operation and recovery operation of UAF after long-term starvation(234 days)and the changes of microbial community structure were researched.By gradually reducing HRT from 10 h to 4 h,the UAF achieved the treatment performance of pre-starvation after only 50 days recovery operation,in which total COD and soluble COD removal efficiencies reached 66%and 69%,respectively,and the CH_(4) production rate was 0.21 L CH_(4)/g CODremoval.The recovery performance of UAF after long term starvation showed that the recovery sequence of three main anaerobic processes was hydrolytic acidification,hydrogen-acetate production and methanogenesis.High-throughput sequencing results indicated that dominant bacteria associated with hydrolytic acidification process changed from Moduliflexaceae and Trichococcus in stable operation stage to Trichococcus and Romboutsia in recovery stage.Besides,the dominant archaea changed from Methanosaeta(hydrotrophic methanogens)to Methanobacterium(acetotrophic methanogens),showing Methanobacterium was more resistant to starvation environment.Therefore,by using UAF for biological treatment of organic matter,even after a long period of starvation,the system would not be completely destroyed.Once it resumed operation,the treatment performance could be restored in a short period of time.展开更多
Anaerobic digestion(AD),as an eco-friendly biological process,shows potential for the decomposition of leachate produced by waste incineration power plants.In this study,the effects of Fe oxides nano-modified pumice(F...Anaerobic digestion(AD),as an eco-friendly biological process,shows potential for the decomposition of leachate produced by waste incineration power plants.In this study,the effects of Fe oxides nano-modified pumice(FNP)were investigated on the fresh leachate AD process.Firstly,a simple hydrothermal method was used to prepare FNP,then introduced into the UASB reactor to evaluate its AD efficiency.Results showed that the inclusion of FNP could shorten the lag phase by 10 days compared to the control group.Furthermore,cumulative methane production in the FNP group was enhanced by 20.11%.Mechanistic studies suggested that hydrogenotrophic methanogenesis in the FNP group was more pronounced due to the influence of key enzymes(i.e.,dehydrogenase and coenzyme F420).Microbial community analysis demonstrated that FNP could enhance the abundance of Methanosarcina,Proteobacteria,Sytrophomonas,and Limnobacter,which might elevate enzyme activity involved in methane production.These findings suggest that FNP might mediate interspecies electron transfer among these microorganisms,which is essential for efficient leachate treatment.展开更多
Climate change has increased drought frequency and duration that are exacerbated by increased temperatures globally.This effect has,and will continue,to increase fire occurrence across many regions of North America.In...Climate change has increased drought frequency and duration that are exacerbated by increased temperatures globally.This effect has,and will continue,to increase fire occurrence across many regions of North America.In the southern Appalachian Mountains,wildfires with high burn severity occurred in 2016due to increased drought and human activity.To investigate the effects of burn severity on soil physicochemical properties,microbial extracellular enzyme production,and microbial abundances in a temperate region,surface soils(0-15 cm)were collected from two sites(the Great Smoky Mountains National Park in Tennessee and the Nantahala National Forest in North Carolina,USA)spanning lightly,moderately,and severely burned areas,accompanied by adjacent unburned locations that act as controls.The soil samples were collected at three time points between 2017 and 2019(i.e.,0.5,1,and 2.5 years post-fire)among burn severity plots.Total hydrolytic enzyme production varied over time,with severe burn plots having significantly lower enzyme production at 2.5years post-fire.Individual enzymes varied among burn severities and across time post-fire.Light burn plots showed greater carbon-specific(β-glucosidase andβ-xylosidase)and phosphorus-specific(acid phosphatase)enzyme activities at 0.5 years post-fire,but this effect was transient.At 2.5 years post-fire,theβ-xylosidase and acid phosphatase activities were lower in severe or moderate burn plots relative to the controls.In contrast,the activity of nitrogen-specific enzyme leucyl aminopeptidase was the lowest in severe burn plots at 0.5 years post-fire,but was the lowest in light burn plots at 2.5 years post-fire.The fungi:bacteria ratio declined with burn severity,indicating that fungi are sensitive or less resilient to high burn severity during recovery.These results suggest that wildfires alter trajectories for soil microbial structure and function within a 2.5-year timeframe,which potentially has long-term impacts on biogeochemical cycling.展开更多
The use of nitrification inhibitors has been suggested as a strategy to decrease cadmium(Cd)accumulation in crops.However,the most efficient nitrification inhibitor for mitigating crop Cd accumulation remains to be el...The use of nitrification inhibitors has been suggested as a strategy to decrease cadmium(Cd)accumulation in crops.However,the most efficient nitrification inhibitor for mitigating crop Cd accumulation remains to be elucidated,and whether and how changes in soil microbial structure are involved in this process also remains unclear.To address these questions,this study applied three commercial nitrification inhibitors,namely,dicyandiamide(DCD),3,4-dimethylpyrazole phosphate(DMPP),and nitrapyrin(NP),to pakchoi.The results showed that both DCD and DMPP(but not NP)could efficiently decrease Cd concentrations in pakchoi in urea-and ammonium-fertilized soils.In addition,among the three tested nitrification inhibitors,DMPP was the most efficient in decreasing the Cd concentration in pakchoi.The nitrification inhibitors decreased pakchoi Cd concentrations by suppressing acidification-induced Cd availability and reshaping the soil microbial structure;the most effective nitrification inhibitor was DMPP.Ammonia oxidation generates the most protons during nitrification and is inhibited by nitrification inhibitors.Changes in environmental factors and predatory bacterial abundance caused by the nitrification inhibitors changed the soil microbial structure and increased the potential participants in plant Cd accumulation.In summary,our study identified DMPP as the most efficient nitrification inhibitor for mitigating crop Cd contamination and observed that the soil microbial structural changes caused by the nitrification inhibitors contributed to decreasing Cd concentration in pakchoi.展开更多
Biolog, 16S rRNA gene denaturing gradient gel electrophoresis （DGGE）, and phospholipid fatty acid （PLFA） analyses were used to assess soil microbial community characteristics in a chronosequence of tea garden syst...Biolog, 16S rRNA gene denaturing gradient gel electrophoresis （DGGE）, and phospholipid fatty acid （PLFA） analyses were used to assess soil microbial community characteristics in a chronosequence of tea garden systems （8-, 50-, and 90- year-old tea gardens）, an adjacent wasteland, and a 90-year-old forest. Biolog analysis showed that the average well color development （AWCD） of all carbon sources and the functional diversity based on the Shannon index decreased （P 〈 0.05） in the following order： wasteland 〉 forest 〉 tea garden. For the DCCE analysis, the genetic diversity based on the Shannon index was significantly lower in the tea garden soils than in the wasteland. However, compared to the 90-year-old forest, the tea garden soils showed significantly higher genetic diversity. PLFA analysis showed that the ratio of Gram positive bacteria to Cram negative bacteria was significantly higher in the tea garden soils than in the wasteland, and the highest value was found in the 90-year-old forest. Both the fungal PLFA and the ratio of fungi to bacteria were significantly higher in the three tea garden soils than in the wasteland and forest, indicating that fungal PLFA was significantly affected by land-use change. Based on cluster analysis of the soil microbial community structure, all three analytical methods showed that land-use change had a greater effect on soil microbial community structure than tea garden age.展开更多
Comparisons of microbial community structure, in eight filter media of zeolites, anthracite, shale, vermiculite, ceramic filter media, gravel, steel slag and bio-ceramic, were undertaken by analyzing the phospholipid ...Comparisons of microbial community structure, in eight filter media of zeolites, anthracite, shale, vermiculite, ceramic filter media, gravel, steel slag and bio-ceramic, were undertaken by analyzing the phospholipid fatty acid （PLFA） composition. A total of 20 fatty acids in the range of C18to C20 were determined but only 13 PLFAs were detected in steel slag. They consist of saturated fatty acids, branched fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids. The variation of fatty acids was revealed in the relative proportions of these fatty acids in different media. The aerobic prokaryotes were the predominant group in all media. The PLFA composition showed significant differences among the eight different media by Tukey＇s honestly test. It was found that steel slag was significantly different in the microbial community as compared to other filter media, probably due to its alkaline effluent. Steel slag alone is probably not a good choice of substratum in constructed wetlands. The principle components analysis （PCA） showed that zeolites, bio-ceramic, shale and vermiculite had a similar microbial community structure while steel slag and ceramic filter media were distinct from other media.展开更多
Many studies have shown soil degradation after the conversion of native forests to exotic Eucalyptus plantations. However, few studies have investigated the long-term impacts of short-rotation forestry practices on so...Many studies have shown soil degradation after the conversion of native forests to exotic Eucalyptus plantations. However, few studies have investigated the long-term impacts of short-rotation forestry practices on soil microorganisms. The impacts of Eucalyptus successive rotations on soil microbial communities were evaluated by comparing phospholipid fatty acid （PLFA） abundances, compositions, and enzyme activities of native Pinus massoniana plantations and adjacent 1st, 2nd, 3rd, 4th generation Eucalyptus plantations. The conversion from P. massoniana to Eucalyptus plantations significantly decreased soil microbial community size and enzyme activities, and increased microbial physiological stress. However, the PLFA abundances formed ＂U＂ shaped quadratic functions with Eucalyptus plantation age. Alternatively, physiological stress biomarkers, the ratios of monounsaturated to saturated fatty acid and Gram＋ to Gram- bacteria, formed ＂∩＂ shaped quadratic functions, and the ratio of cy17：0 to 16： 1ω7c decreased with plantation age. The activities of phenol oxidase, peroxidase, and acid phosphatase increased with Eucalyptus plantation age, while the cellobiobydrolase activity formed ＂U＂ shaped quadratic functions. Soil N：P, alkaline hydrolytic nitrogen, soil organic carbon, and understory cover largely explained the variation in PLFA profiles while soil N：P, alkaline hydrolytic nitrogen, and understory cover explained most of the variability in enzyme activity. In conclusion, soil microbial structure and function under Eucalyptus plantations were strongly impacted by plantation age. Most of the changes could be explained by altered soil resource availability and understory cover associated with successive planting of Eucalyptus. Our results highlight the importance of plantation age for assessing the impacts of plantation conversion as well as the importance of reducing disturbance for plantation management.展开更多
With 110-d incubation experiment in laboratory, the responses of microbial quantity, soil enzymatic activity, and bacterial community structure to different amounts of diesel fuel amendments were studied to reveal whe...With 110-d incubation experiment in laboratory, the responses of microbial quantity, soil enzymatic activity, and bacterial community structure to different amounts of diesel fuel amendments were studied to reveal whether certain biological and biochemical characteristics could serve as reliable indicators of petroleum hydrocarbon contamination in meadow-brown soil, and use these indicators to evaluate the actual ecological impacts of 50-year petroleum-refining wastewater irrigation on soil function in Shenfu irrigation area. Results showed that amendments of ~ 1000 mg/kg diesel fuel stimulated the growth of aerobic heterotrophic bacteria, and increased the activity of soil dehydrogenase, hydrogenperoxidase, polyphenol oxidase and substrate-induced respiration. Soil bacterial diversity decreased slightly during the first 15 d of incubation and recovered to the control level on day 30. The significant decrease of the colony forming units of soil actinomyces and filamentous fungi can be taken as the sensitive biological indicators of petroleum contamination when soil was amended with 〉15000 mg/kg diesel fuel. The sharp decrease in urease activity was recommended as the most sensitive biochemical indicator of heavy diesel fuel contamination. The shifts in community structure to a community documented by Sphingomonadaceae within a-subgroup of Proteobacteria could be served as a sensitive and precise indicator of diesel fuel contamination. Based on the results described in this paper, the soil function in Shenfu irrigation area was disturbed to some extent.展开更多
The Loess Plateau in China is one of the most eroded areas in the world. Accordingly, vegetation restoration has been implemented in this area over the past two decades to remedy the soil degradation problem. Understa...The Loess Plateau in China is one of the most eroded areas in the world. Accordingly, vegetation restoration has been implemented in this area over the past two decades to remedy the soil degradation problem. Understanding the microbial community structure is essential for the sustainability of ecosystems and for the reclamation of degraded arable land. This study aimed to determine the effect of different vegetation types on microbial processes and community structure in rhizosphere soils in the Loess Plateau. The six vegetation types were as follows：two natural grassland （Artemisia capillaries and Heteropappus altaicus）, two artificial grassland （Astragalus adsurgens and Panicum virgatum）, and two artificial shrubland （Caragana korshinskii and Hippophae rhamnoides） species. The microbial community structure and functional diversity were examined by analyzing the phospholipid fatty acids （PLFAs） and community-level physiological profiles. The results showed that rhizosphere soil sampled from the H. altaicus and A. capillaries plots had the highest values of microbial biomass C, average well color development of carbon resources, Gram-negative （G-） bacterial PLFA, bacterial PLFA, total PLFA, Shannon richness, and Shannon evenness, as well as the lowest metabolic quotient. Soil sampled from the H. rhamnoides plots had the highest metabolic quotient and Gram-positive （G＋） bacterial PLFA, and soil sampled from the A. adsurgens and A. capillaries plots had the highest fungal PLFA and fungal：bacterial PLFA ratio. Correlation analysis indicated a signiifcant positive relationship among the microbial biomass C, G- bacterial PLFA, bacterial PLFA, and total PLFA. In conclusion, plant species under arid climatic conditions signiifcantly affected the microbial community structure in rhizosphere soil. Among the studied plants, natural grassland species generated the most favorable microbial conditions.展开更多
With the rapid expansion of livestock production,the amount of livestock wastewater accumulated rapidly.Lack of biodegradable organic matter makes denitrification of livestock wastewater after anaerobic digestion more...With the rapid expansion of livestock production,the amount of livestock wastewater accumulated rapidly.Lack of biodegradable organic matter makes denitrification of livestock wastewater after anaerobic digestion more difficult.In this study,Myriophyllum aquaticum constructed wetlands(CWs)with efficient nitrogen removal performance were established under different carbon/nitrogen(C/N)ratios.Analysis of community composition reveals the change of M.aquaticum CWs in microbial community structure with C/N ratios.The proportion of Proteobacteria which is one of the dominant phyla among denitrifier communities increased significantly under low C/N ratio conditions.Besides,to obtain cultivable denitrifier that could be added into CWs in situ,33 strains belonging to phylum Proteobacteria were isolated from efficient M.aquaticum CWs,while the best-performing denitrification strain M3-1 was identified as Bacillus velezensis JT3-1(GenBank No.CP032506.1).Redundancy analysis and quadratic models showed that C/N ratio had significant effects on disposal of nitrate(NO_(3)^(−)-N)and the strains isolated could perform well in denitrification when C/N ratio is relatively low.In addition,they have relatively wide ranges of carbon sources,temperature and a high NO_(3)^(−)removal rate of 9.12 mg/(L·hr)at elevated concentrations of 800 mg/L nitrate.Thus,strains isolated from M.aquaticum CWs with low C/N ratio have a practical application value in the treatment of nitrate-containing wastewater.These denitrifying bacteria could be added to CWs to enhance nitrogen removal efficiency of CWs for livestock wastewater with low C/N ratio in the future.展开更多
Solid or liquid waste containing a high concentration of nicotine can pollute sediment in rivers and lakes, and may destroy the ecological balance if it is directly discharged into the environment without any treatmen...Solid or liquid waste containing a high concentration of nicotine can pollute sediment in rivers and lakes, and may destroy the ecological balance if it is directly discharged into the environment without any treatment. In this study, the polymerase chain reaction （PCR） and denaturing gradient gel electrophoresis （DGGE） method was used to analyze the variation of the microbial community structure in the control and nicotinecontaminated sediment samples with nicotine concentration and time of exposure. The results demonstrated that the growth of some bacterial species in the nicotine-contaminated sediment samples was inhibited during the exposure. Some bacteria decreased in species diversity and in quantity with the increase of nicotine concentration or time of exposure, while other bacteria were enriched under the effect of nicotine, and their DGGE bands changed from undertones to deep colors. The microbial community structure, however, showed a wide variation in the nicotine- contaminated sediment samples, especially in the sediment samples treated with high-concentration nicotine. The Jaccard index was only 35.1% between the initial sediment sample and the sediment sample with a nicotine concentration of 0.030 μg/g after 28 d of exposure. Diversity indices showed that the contaminated groups had a similar trend over time. The diversity indices of contaminated groups all decreased in the first 7 d after exposure, then increased until day 42. It has been found that nicotine decreased the diversity of the microbial community in the sediment.展开更多
Microorganisms regulate the responses of terrestrial ecosystems to anthropogenic nutrient inputs.The escalation of anthropogenic activities has resulted in a rise in the primary terrestrial constraining elements,namel...Microorganisms regulate the responses of terrestrial ecosystems to anthropogenic nutrient inputs.The escalation of anthropogenic activities has resulted in a rise in the primary terrestrial constraining elements,namely nitrogen(N)and phosphorus(P).Nevertheless,the specific mechanisms governing the influence of soil microbial community structure and ecological processes in ecologically vulnerable and delicate semi-arid loess agroecosystems remain inadequately understood.Therefore,we explored the effects of different N and P additions on soil microbial community structure and its associated ecological processes in the farmland of Chinese Loess Plateau based on a 36-a long-term experiment.Nine fertilization treatments with complete interactions of high,medium,and low N and P gradients were set up.Soil physical and chemical properties,along with the microbial community structure were measured in this study.Additionally,relevant ecological processes such as microbial biomass,respiration,N mineralization,and enzyme activity were quantified.To elucidate the relationships between these variables,we examined correlation-mediated processes using statistical techniques,including redundancy analysis(RDA)and structural equation modeling(SEM).The results showed that the addition of N alone had a detrimental effect on soil microbial biomass,mineralized N accumulation,andβ-1,4-glucosidase activity.Conversely,the addition of P exhibited an opposing effect,leading to positive influences on these soil parameters.The interactive addition of N and P significantly changed the microbial community structure,increasing microbial activity(microbial biomass and soil respiration),but decreasing the accumulation of mineralized N.Among them,N24P12 treatment showed the greatest increase in the soil nutrient content and respiration.N12P12 treatment increased the overall enzyme activity and total phospholipid fatty acid(PLFA)content by 70.93%.N and P nutrient contents of the soil dominate the microbial community structure and the corresponding changes in hydrolytic enzymes.Soil microbial biomass,respiration,and overall enzyme activity are driven by mineralized N.Our study provides a theoretical basis for exploring energy conversion processes of soil microbial community and environmental sustainability under long-term N and P additions in semi-arid loess areas.展开更多
Plant growth-promoting rhizobacteria （PGPR） have been widely recognized as an important agent, especially as a biofertilizer, in agricultural systems. The objectives of this study were to select effective PGPR for C...Plant growth-promoting rhizobacteria （PGPR） have been widely recognized as an important agent, especially as a biofertilizer, in agricultural systems. The objectives of this study were to select effective PGPR for Chinese kale （Brassica oleracea var. alboglabra） cultivation and to investigate the effect of their inoculation on indigenous microbial community structure. The Bacillus sp. SUT1 and Pseudomonas sp. SUT19 were selected for determining the efficiency in promoting Chinese kale growth in both pot and field experiments. In the field experiment, PGPR amended with compost gave the highest yields among all treatments. The Chinese kale growth promotion may be directly affected by PGPR inoculation. The changes of microbial community structure in the rhizosphere of Chinese kale following PGPR inoculation were examined by denaturing gradient gel electrophoresis （DGGE） and principal coordinate analysis. The DGGE fingerprints of 16S rDNA amplified from total community DNA in the rhizosphere confirmed that our isolates were established in the rhizosphere throughout this study. The microbial community structures were slightly different among all the treatments, and the major changes depended on stages of plant growth. DNA sequencing of excised DGGE bands showed that the dominant species in microbial community structure in the rhizosphere were not mainly interfered by PGPR, but strongly influenced by plant development. The microbial diversity as revealed by diversity indices was not different between the PGPR-inoculated and uninoculated treatments. In addition, the rhizosphere soil had more influence on eubacterial diversity, whereas it did not affect archaebacterial and fungal diversities.展开更多
To investigate the effects of silver nanoparticles(Ag NPs)and low temperature double-pressure on the wastewater treatment efficacy and the microbial community structure of constructed wetlands,a pilot-scale vertical f...To investigate the effects of silver nanoparticles(Ag NPs)and low temperature double-pressure on the wastewater treatment efficacy and the microbial community structure of constructed wetlands,a pilot-scale vertical flow constructed wetland was set up to treat synthetic wastewater under laboratory conditions.By measuring the effluent concentration of ammonia nitrogen(NH_(4)^(+)-N),total nitrogen(TN),total phosphorus(TP),chemical oxygen demand(COD),and the diversity,richness,and community structure of microorganisms of the upper and lower soil layers in the wetland,the nutrient removal effect of the constructed wetland and the changes in the microflora of the soil layer were studied.The results reveal that the correlation coefficients between the removal rates of TN and NH_(4)^(+)-N and the temperature are 0.463 and 0.692,respectively,indicating a significant positive correlation.From the warm to the cold season,both the diversity and richness of microorganisms in the lower soil layer of wetlands are inhibited under the double-pressure of Ag NPs and low temperature,and the abundances of the denitrogenation functional bacteria such as Candidatus nitrososphaera,Sulfuritalea,Anaeromyxobacter,Candidatus solibacter,Nitrospira,and Zoogloea are altered.Low temperature and Ag NPs exposure can thus affect the wastewater treatment performance of constructed wetlands,possibly because of the seasonal changes of the microflora.展开更多
The chemical oxygen demand（COD） and NH3-N removal, membrane fouling, sludge characteristics and microbial community structure in a membrane bioreactor（MBR） coupled with worm reactors（SSBWR） were evaluated for 21...The chemical oxygen demand（COD） and NH3-N removal, membrane fouling, sludge characteristics and microbial community structure in a membrane bioreactor（MBR） coupled with worm reactors（SSBWR） were evaluated for 210 days. The obtained results were compared to those from a conventional MBR（C-MBR） operated in parallel. The results indicated that the combined MBR（S-MBR） achieved higher COD and NH3-N removal efficiency,slower increase in membrane fouling, better sludge settleability and higher activities of the related enzymes in the activated sludge. Denaturing gradient gel electrophoresis was used to analyze the microbial community structures in the C-MBR and the S-MBR. The microbial community structure in the S-MBR was more diverse than that in the C-MBR. Additionally, the slow-growing microbes such as Saprospiraceae, Actinomyces, Frankia, Clostridium, Comamonas,Pseudomonas, Dechloromonas and Flavobacterium were enriched in the S-MBR, further accounting for the sludge reduction, membrane fouling alleviation and wastewater treatment.展开更多
Exploration of soil environmental characteristics governing soil microbial community structure and activity may improve our understanding of biogeochemical processes and soil quality. The impact of soil environmental ...Exploration of soil environmental characteristics governing soil microbial community structure and activity may improve our understanding of biogeochemical processes and soil quality. The impact of soil environmental characteristics especially organic carbon availability after 15-yr different organic and inorganic fertilizer inputs on soil bacterial community structure and functional metabolic diversity of soil microbial communities were evaluated in a 15-yr fertilizer experiment in Changping County, Beijing, China. The experiment was a wheat-maize rotation system which was established in 1991 including four different fertilizer treatments. These treatments included： a non-amended control（CK）, a commonly used application rate of inorganic fertilizer treatment（NPK）; a commonly used application rate of inorganic fertilizer with swine manure incorporated treatment（NPKM）, and a commonly used application rate of inorganic fertilizer with maize straw incorporated treatment（NPKS）. Denaturing gradient gel electrophoresis（DGGE） of the 16 S r RNA gene was used to determine the bacterial community structure and single carbon source utilization profiles were determined to characterize the microbial community functional metabolic diversity of different fertilizer treatments using Biolog Eco plates. The results indicated that long-term fertilized treatments significantly increased soil bacterial community structure compared to CK. The use of inorganic fertilizer with organic amendments incorporated for long term（NPKM, NPKS） significantly promoted soil bacterial structure than the application of inorganic fertilizer only（NPK）, and NPKM treatment was the most important driver for increases in the soil microbial community richness（S） and structural diversity（H）. Overall utilization of carbon sources by soil microbial communities（average well color development, AWCD） and microbial substrate utilization diversity and evenness indices（H＇ and E） indicated that long-term inorganic fertilizer with organic amendments incorporated（NPKM, NPKS） could significantly stimulate soil microbial metabolic activity and functional diversity relative to CK, while no differences of them were found between NPKS and NPK treatments. Principal component analysis（PCA） based on carbon source utilization profiles also showed significant separation of soil microbial community under long-term fertilization regimes and NPKM treatment was significantly separated from the other three treatments primarily according to the higher microbial utilization of carbohydrates, carboxylic acids, polymers, phenolic compounds, and amino acid, while higher utilization of amines/amides differed soil microbial community in NPKS treatment from those in the other three treatments. Redundancy analysis（RDA） indicated that soil organic carbon（SOC） availability, especially soil microbial biomass carbon（Cmic） and Cmic/SOC ratio are the key factors of soil environmental characteristics contributing to the increase of both soil microbial community structure and functional metabolic diversity in the long-term fertilization trial. Our results showed that long-term inorganic fertilizer and swine manure application could significantly improve soil bacterial community structure and soil microbial metabolic activity through the increases in SOC availability, which could provide insights into the sustainable management of China＇s soil resource.展开更多
基金Project(51878662)supported by the National Natural Science Foundation of ChinaProject(2017SK2420)supported by the Science and Technology of Hunan Province,ChinaProject(2019JJ20033)supported by the Distinguished Youth Natural Science Foundation of Hunan Province,China。
文摘In this study, a lab-scale upflow anaerobic sludge blanket(UASB) reactor was applied to studying the high-rate nitrogen removal of granule-based anammox process. The nitrogen removal rate(NRR) finally improved to 15.77 kg/m3/d by shortening hydraulic retention time(HRT) to 1.06 h. Well-shaped red anammox granules were extensively enriched inside the reactor. The results of nitrogen removal kinetics indicated that the present bioreactor has great nitrogen removal potential, because the maximum rate of substrate utilization(Umax) predicted by Stover-Kincannon model is suggested as 55.68 kg/(m3·d). Analysis of the microbial community showed that the anammox genus Candidatus Kuenenia dominated the bacterial communities. The relative abundance of Candidatus Kuenenia rose from 12.29% to 36.95% after progressively shorter HRT and higher influent substrate concentrations, illustrating the stability of nitrogen removal performance and biomass enrichment offered by the UASB in carrying out high-rate anammox process.
基金supported by the Zhejiang Provincial Natural Science Foundation,China(Grant No.LQ24C010007)Zhejiang Science and Technology Major Program on Rice New Variety Breeding,China(Grant No.2021C02063)+4 种基金the Agricultural Sciences and Technologies Innovation Program,China(Grant No.CAAS-CSCB-202301)the Key Projects of Zhejiang Provincial Natural Science Foundation,China(Grant No.LZ23C130002)the Youth Innovation Program of Chinese Academy of Agricultural Sciences(Grant No.Y2023QC22)the Joint Open Competitive Project of the Yazhou Bay Seed Laboratory and China National Seed Company Limited(Grant Nos.B23YQ1514 and B23CQ15EP)the External Cooperation Projects of Biotechnology Research Institute,Fujian Academy of Agricultural Sciences,China(Grant No.DWHZ2024-07).
文摘Rice seedling blight,caused by various fungi,including Fusarium oxysporum,poses a severe threat to rice production.As awareness grows regarding the environmental and safety hazards associated with the application of fungicides for managing rice seedling blight,there has been a shift in focus towards biological control agents.In this study,we isolated biocontrol bacteria from paddy fields that significantly inhibited the growth of F.oxysporum in vitro and identified the strains as Bacillus amyloliquefaciens T40 and Bacillus pumilus T208.Additionally,our findings indicated that the combined application of these Bacillus strains in soil was more effective in reducing the incidence of rice seedling blight than their individual use.Analysis of 16S and internal transcribed spacer rRNA gene sequencing data revealed that the mixture of the T40 and T208 strains exhibited the lowest average clustering coefficients,which were negatively correlated with the biomass of F.oxysporum-inoculated rice seedlings.Furthermore,this mixture led to higher stochastic assembly(average|βNTI|<2)and reduced selection pressures on rice rhizosphere bacteria compared with individual strain applications.The mixture of the T40 and T208 strains also significantly increased the expression of defense-related genes.In conclusion,the mixture of the T40 and T208 strains effectively modulates microbial community structures,enhances microbial network stability,and boosts the resistance against rice seedling blight.Our study supports the development and utilization of biological resources for crop protection.
基金supported by the National Natural Science Foundation of China(Nos.42222102,41971136,and 42171107)the Jilin Provincial Department of Science and Technology,China(No.20230508089RC)the Professional Association of the Alliance of International Science Organizations(No.ANSO-PA-2020-14).
文摘Global climate change exerts profound effects on snow cover,with consequential impacts on microbial activities and the stability of soil organic carbon(SOC)within aggregates.Northern peatlands are significant carbon reservoirs,playing a critical role in mitigating climate change.However,the effects of snow variations on microbial-mediated SOC stability within aggregates in peatlands remain inadequately understood.Here,an in-situ field experiment manipulating snow conditions(i.e.,snow removal and snow cover)was conducted to investigate how snow variations affect soil microbial community and the associated SOC stability within soil aggregates(>2,0.25-2,and<0.25 mm)in a peatland of Northeast China.The results showed that snow removal significantly increased the SOC content and stability within aggregates.Compared to the soils with snow cover,snow removal resulted in decreased soil average temperatures in the topsoil(0-30 cm depth)and subsoil(30-60 cm depth)(by 1.48 and 1.34°C,respectively)and increased freeze-thaw cycles(by 11 cycles),consequently decreasing the stability of aggregates in the topsoil and subsoil(by 23.68%and 6.85%,respectively).Furthermore,more recalcitrant carbon and enhanced SOC stability were present in microaggregates(<0.25 mm)at two soil depths.Moreover,reductions in bacterial diversity and network stability were observed in response to snow removal.Structural equation modeling analysis demonstrated that snow removal indirectly promoted(P<0.01)SOC stability by regulating carbon to nitrogen(C:N)ratio within aggregates.Overall,our study suggested that microaggregate protection and an appropriate C:N ratio enhanced carbon sequestration in response to climate change.
基金Supported by Tangshan Talent Funding Project(A202202005)Dairy Industry Revitalization Major Technological Innovation Project of Hebei Key Research and Development Program(19227516D)High-level Talents Funding Project of Hebei Province(A201803034).
文摘[Objectives]This study was conducted to investigate the influence mechanisms of microbial succession in raw milk under cold storage at different temperatures.[Methods]A raw milk sample was collected from a local large-scale farm in Tangshan and divided into four treatment gradients:a control group(M)rapidly frozen at-80℃,and three experimental groups stored at 4℃(T),6℃(F),and 8℃(Y),respectively.A time series experiment was carried out according to time intervals of 24,48 and 72 h in each experimental group.Traditional microbial culture methods and 16S rRNA high-throughput sequencing were combined to analyze the dynamic changes in microbial abundance and structural variation.[Results]Plate counting revealed significantly lower total bacterial count and psychrotrophic bacteria in the 4℃storage group within 24 h compared with other treatment groups(P<0.01),confirming that maintaining low-temperature cold chain integrity and controlling treatment time(<24 h)can effectively inhibit microbial metabolic activity.16S rRNA sequencing analysis revealed high initial microbial diversity in raw milk,with dominant genera being Lactococcus,Acinetobacter,and Pseudomonas.Low-temperature treatment effectively reduced theαdiversity index of the microbial community.During the later stage of cold storage at 4℃,the relative abundance of Pseudomonas increased to over 90%,making it the dominant bacterial genus.[Conclusions]This study has significant application value for maintaining the quality of milk and dairy products and prolonging their shelf life.
基金supported by the National Natural Science Foundation of China(No.52270018).
文摘The organic matter inmunicipal wastewater can be recovered by anaerobic biological treatment,making further resource utilization of municipal wastewater,which meets the requirements of sustainable development.An upflow anaerobic biofilter(UAF)treating municipal wastewater was established.The performances of stable operation and recovery operation of UAF after long-term starvation(234 days)and the changes of microbial community structure were researched.By gradually reducing HRT from 10 h to 4 h,the UAF achieved the treatment performance of pre-starvation after only 50 days recovery operation,in which total COD and soluble COD removal efficiencies reached 66%and 69%,respectively,and the CH_(4) production rate was 0.21 L CH_(4)/g CODremoval.The recovery performance of UAF after long term starvation showed that the recovery sequence of three main anaerobic processes was hydrolytic acidification,hydrogen-acetate production and methanogenesis.High-throughput sequencing results indicated that dominant bacteria associated with hydrolytic acidification process changed from Moduliflexaceae and Trichococcus in stable operation stage to Trichococcus and Romboutsia in recovery stage.Besides,the dominant archaea changed from Methanosaeta(hydrotrophic methanogens)to Methanobacterium(acetotrophic methanogens),showing Methanobacterium was more resistant to starvation environment.Therefore,by using UAF for biological treatment of organic matter,even after a long period of starvation,the system would not be completely destroyed.Once it resumed operation,the treatment performance could be restored in a short period of time.
基金supported by the National Key Research and Development Program of China(No.2019YFC0408500)the Scientific Research Project of China State Construction Engineering Corporation Limited(CSCEC-2022-K-(36))the Scientific Research Project of CSCEC AECOM Consultants Corporation Limited(XBSZKY2216).
文摘Anaerobic digestion(AD),as an eco-friendly biological process,shows potential for the decomposition of leachate produced by waste incineration power plants.In this study,the effects of Fe oxides nano-modified pumice(FNP)were investigated on the fresh leachate AD process.Firstly,a simple hydrothermal method was used to prepare FNP,then introduced into the UASB reactor to evaluate its AD efficiency.Results showed that the inclusion of FNP could shorten the lag phase by 10 days compared to the control group.Furthermore,cumulative methane production in the FNP group was enhanced by 20.11%.Mechanistic studies suggested that hydrogenotrophic methanogenesis in the FNP group was more pronounced due to the influence of key enzymes(i.e.,dehydrogenase and coenzyme F420).Microbial community analysis demonstrated that FNP could enhance the abundance of Methanosarcina,Proteobacteria,Sytrophomonas,and Limnobacter,which might elevate enzyme activity involved in methane production.These findings suggest that FNP might mediate interspecies electron transfer among these microorganisms,which is essential for efficient leachate treatment.
基金funded by a 2017 Highlands Biological Station Grant-in-Aide,the University of Texas at San Antonio, and the University of Memphis
文摘Climate change has increased drought frequency and duration that are exacerbated by increased temperatures globally.This effect has,and will continue,to increase fire occurrence across many regions of North America.In the southern Appalachian Mountains,wildfires with high burn severity occurred in 2016due to increased drought and human activity.To investigate the effects of burn severity on soil physicochemical properties,microbial extracellular enzyme production,and microbial abundances in a temperate region,surface soils(0-15 cm)were collected from two sites(the Great Smoky Mountains National Park in Tennessee and the Nantahala National Forest in North Carolina,USA)spanning lightly,moderately,and severely burned areas,accompanied by adjacent unburned locations that act as controls.The soil samples were collected at three time points between 2017 and 2019(i.e.,0.5,1,and 2.5 years post-fire)among burn severity plots.Total hydrolytic enzyme production varied over time,with severe burn plots having significantly lower enzyme production at 2.5years post-fire.Individual enzymes varied among burn severities and across time post-fire.Light burn plots showed greater carbon-specific(β-glucosidase andβ-xylosidase)and phosphorus-specific(acid phosphatase)enzyme activities at 0.5 years post-fire,but this effect was transient.At 2.5 years post-fire,theβ-xylosidase and acid phosphatase activities were lower in severe or moderate burn plots relative to the controls.In contrast,the activity of nitrogen-specific enzyme leucyl aminopeptidase was the lowest in severe burn plots at 0.5 years post-fire,but was the lowest in light burn plots at 2.5 years post-fire.The fungi:bacteria ratio declined with burn severity,indicating that fungi are sensitive or less resilient to high burn severity during recovery.These results suggest that wildfires alter trajectories for soil microbial structure and function within a 2.5-year timeframe,which potentially has long-term impacts on biogeochemical cycling.
基金Zhejiang Provincial Natural Science Foundation of China(No.LZ21D010010).
文摘The use of nitrification inhibitors has been suggested as a strategy to decrease cadmium(Cd)accumulation in crops.However,the most efficient nitrification inhibitor for mitigating crop Cd accumulation remains to be elucidated,and whether and how changes in soil microbial structure are involved in this process also remains unclear.To address these questions,this study applied three commercial nitrification inhibitors,namely,dicyandiamide(DCD),3,4-dimethylpyrazole phosphate(DMPP),and nitrapyrin(NP),to pakchoi.The results showed that both DCD and DMPP(but not NP)could efficiently decrease Cd concentrations in pakchoi in urea-and ammonium-fertilized soils.In addition,among the three tested nitrification inhibitors,DMPP was the most efficient in decreasing the Cd concentration in pakchoi.The nitrification inhibitors decreased pakchoi Cd concentrations by suppressing acidification-induced Cd availability and reshaping the soil microbial structure;the most effective nitrification inhibitor was DMPP.Ammonia oxidation generates the most protons during nitrification and is inhibited by nitrification inhibitors.Changes in environmental factors and predatory bacterial abundance caused by the nitrification inhibitors changed the soil microbial structure and increased the potential participants in plant Cd accumulation.In summary,our study identified DMPP as the most efficient nitrification inhibitor for mitigating crop Cd contamination and observed that the soil microbial structural changes caused by the nitrification inhibitors contributed to decreasing Cd concentration in pakchoi.
基金the National Natural Science Foundation of China (Nos.30671207 and 40371063).
文摘Biolog, 16S rRNA gene denaturing gradient gel electrophoresis （DGGE）, and phospholipid fatty acid （PLFA） analyses were used to assess soil microbial community characteristics in a chronosequence of tea garden systems （8-, 50-, and 90- year-old tea gardens）, an adjacent wasteland, and a 90-year-old forest. Biolog analysis showed that the average well color development （AWCD） of all carbon sources and the functional diversity based on the Shannon index decreased （P 〈 0.05） in the following order： wasteland 〉 forest 〉 tea garden. For the DCCE analysis, the genetic diversity based on the Shannon index was significantly lower in the tea garden soils than in the wasteland. However, compared to the 90-year-old forest, the tea garden soils showed significantly higher genetic diversity. PLFA analysis showed that the ratio of Gram positive bacteria to Cram negative bacteria was significantly higher in the tea garden soils than in the wasteland, and the highest value was found in the 90-year-old forest. Both the fungal PLFA and the ratio of fungi to bacteria were significantly higher in the three tea garden soils than in the wasteland and forest, indicating that fungal PLFA was significantly affected by land-use change. Based on cluster analysis of the soil microbial community structure, all three analytical methods showed that land-use change had a greater effect on soil microbial community structure than tea garden age.
基金supported by the National Natural Science Foundation of China (No.30870221,20877093,50808172)the High Technology Research and Development Program (863) of China (No.2009X207209-004)
文摘Comparisons of microbial community structure, in eight filter media of zeolites, anthracite, shale, vermiculite, ceramic filter media, gravel, steel slag and bio-ceramic, were undertaken by analyzing the phospholipid fatty acid （PLFA） composition. A total of 20 fatty acids in the range of C18to C20 were determined but only 13 PLFAs were detected in steel slag. They consist of saturated fatty acids, branched fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids. The variation of fatty acids was revealed in the relative proportions of these fatty acids in different media. The aerobic prokaryotes were the predominant group in all media. The PLFA composition showed significant differences among the eight different media by Tukey＇s honestly test. It was found that steel slag was significantly different in the microbial community as compared to other filter media, probably due to its alkaline effluent. Steel slag alone is probably not a good choice of substratum in constructed wetlands. The principle components analysis （PCA） showed that zeolites, bio-ceramic, shale and vermiculite had a similar microbial community structure while steel slag and ceramic filter media were distinct from other media.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Science (No.KZCX2-EW-QN406)the National Natural Science Foundation of China (No.31170425,40871130)
文摘Many studies have shown soil degradation after the conversion of native forests to exotic Eucalyptus plantations. However, few studies have investigated the long-term impacts of short-rotation forestry practices on soil microorganisms. The impacts of Eucalyptus successive rotations on soil microbial communities were evaluated by comparing phospholipid fatty acid （PLFA） abundances, compositions, and enzyme activities of native Pinus massoniana plantations and adjacent 1st, 2nd, 3rd, 4th generation Eucalyptus plantations. The conversion from P. massoniana to Eucalyptus plantations significantly decreased soil microbial community size and enzyme activities, and increased microbial physiological stress. However, the PLFA abundances formed ＂U＂ shaped quadratic functions with Eucalyptus plantation age. Alternatively, physiological stress biomarkers, the ratios of monounsaturated to saturated fatty acid and Gram＋ to Gram- bacteria, formed ＂∩＂ shaped quadratic functions, and the ratio of cy17：0 to 16： 1ω7c decreased with plantation age. The activities of phenol oxidase, peroxidase, and acid phosphatase increased with Eucalyptus plantation age, while the cellobiobydrolase activity formed ＂U＂ shaped quadratic functions. Soil N：P, alkaline hydrolytic nitrogen, soil organic carbon, and understory cover largely explained the variation in PLFA profiles while soil N：P, alkaline hydrolytic nitrogen, and understory cover explained most of the variability in enzyme activity. In conclusion, soil microbial structure and function under Eucalyptus plantations were strongly impacted by plantation age. Most of the changes could be explained by altered soil resource availability and understory cover associated with successive planting of Eucalyptus. Our results highlight the importance of plantation age for assessing the impacts of plantation conversion as well as the importance of reducing disturbance for plantation management.
基金Project supported by the National Natural Science Foundation of China(No.30670391)the National Key Basic Researeh and Development Program of China(No.2004CB418505).
文摘With 110-d incubation experiment in laboratory, the responses of microbial quantity, soil enzymatic activity, and bacterial community structure to different amounts of diesel fuel amendments were studied to reveal whether certain biological and biochemical characteristics could serve as reliable indicators of petroleum hydrocarbon contamination in meadow-brown soil, and use these indicators to evaluate the actual ecological impacts of 50-year petroleum-refining wastewater irrigation on soil function in Shenfu irrigation area. Results showed that amendments of ~ 1000 mg/kg diesel fuel stimulated the growth of aerobic heterotrophic bacteria, and increased the activity of soil dehydrogenase, hydrogenperoxidase, polyphenol oxidase and substrate-induced respiration. Soil bacterial diversity decreased slightly during the first 15 d of incubation and recovered to the control level on day 30. The significant decrease of the colony forming units of soil actinomyces and filamentous fungi can be taken as the sensitive biological indicators of petroleum contamination when soil was amended with 〉15000 mg/kg diesel fuel. The sharp decrease in urease activity was recommended as the most sensitive biochemical indicator of heavy diesel fuel contamination. The shifts in community structure to a community documented by Sphingomonadaceae within a-subgroup of Proteobacteria could be served as a sensitive and precise indicator of diesel fuel contamination. Based on the results described in this paper, the soil function in Shenfu irrigation area was disturbed to some extent.
基金supported by the Strategic Technology Project of Chinese Academy of Sciences(XDA05060300)the Science and Technology Research and Development Program of Shaanxi ProvinceChina(2011KJXX63)
文摘The Loess Plateau in China is one of the most eroded areas in the world. Accordingly, vegetation restoration has been implemented in this area over the past two decades to remedy the soil degradation problem. Understanding the microbial community structure is essential for the sustainability of ecosystems and for the reclamation of degraded arable land. This study aimed to determine the effect of different vegetation types on microbial processes and community structure in rhizosphere soils in the Loess Plateau. The six vegetation types were as follows：two natural grassland （Artemisia capillaries and Heteropappus altaicus）, two artificial grassland （Astragalus adsurgens and Panicum virgatum）, and two artificial shrubland （Caragana korshinskii and Hippophae rhamnoides） species. The microbial community structure and functional diversity were examined by analyzing the phospholipid fatty acids （PLFAs） and community-level physiological profiles. The results showed that rhizosphere soil sampled from the H. altaicus and A. capillaries plots had the highest values of microbial biomass C, average well color development of carbon resources, Gram-negative （G-） bacterial PLFA, bacterial PLFA, total PLFA, Shannon richness, and Shannon evenness, as well as the lowest metabolic quotient. Soil sampled from the H. rhamnoides plots had the highest metabolic quotient and Gram-positive （G＋） bacterial PLFA, and soil sampled from the A. adsurgens and A. capillaries plots had the highest fungal PLFA and fungal：bacterial PLFA ratio. Correlation analysis indicated a signiifcant positive relationship among the microbial biomass C, G- bacterial PLFA, bacterial PLFA, and total PLFA. In conclusion, plant species under arid climatic conditions signiifcantly affected the microbial community structure in rhizosphere soil. Among the studied plants, natural grassland species generated the most favorable microbial conditions.
基金supported by the National Natural Science Foundation of China(Nos.42177099 and 91951108)the Key R&D plan of Ningxia Hui Autonomous Region(No.2019BFG02032)the CAS International Partnership Program(No.121311KYSB20200017).
文摘With the rapid expansion of livestock production,the amount of livestock wastewater accumulated rapidly.Lack of biodegradable organic matter makes denitrification of livestock wastewater after anaerobic digestion more difficult.In this study,Myriophyllum aquaticum constructed wetlands(CWs)with efficient nitrogen removal performance were established under different carbon/nitrogen(C/N)ratios.Analysis of community composition reveals the change of M.aquaticum CWs in microbial community structure with C/N ratios.The proportion of Proteobacteria which is one of the dominant phyla among denitrifier communities increased significantly under low C/N ratio conditions.Besides,to obtain cultivable denitrifier that could be added into CWs in situ,33 strains belonging to phylum Proteobacteria were isolated from efficient M.aquaticum CWs,while the best-performing denitrification strain M3-1 was identified as Bacillus velezensis JT3-1(GenBank No.CP032506.1).Redundancy analysis and quadratic models showed that C/N ratio had significant effects on disposal of nitrate(NO_(3)^(−)-N)and the strains isolated could perform well in denitrification when C/N ratio is relatively low.In addition,they have relatively wide ranges of carbon sources,temperature and a high NO_(3)^(−)removal rate of 9.12 mg/(L·hr)at elevated concentrations of 800 mg/L nitrate.Thus,strains isolated from M.aquaticum CWs with low C/N ratio have a practical application value in the treatment of nitrate-containing wastewater.These denitrifying bacteria could be added to CWs to enhance nitrogen removal efficiency of CWs for livestock wastewater with low C/N ratio in the future.
基金supported by the National Natural Science Foundation of China(Grants No.51378175 and 41323001)the Special Fund of the State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering(Grant No.20145028212)
文摘Solid or liquid waste containing a high concentration of nicotine can pollute sediment in rivers and lakes, and may destroy the ecological balance if it is directly discharged into the environment without any treatment. In this study, the polymerase chain reaction （PCR） and denaturing gradient gel electrophoresis （DGGE） method was used to analyze the variation of the microbial community structure in the control and nicotinecontaminated sediment samples with nicotine concentration and time of exposure. The results demonstrated that the growth of some bacterial species in the nicotine-contaminated sediment samples was inhibited during the exposure. Some bacteria decreased in species diversity and in quantity with the increase of nicotine concentration or time of exposure, while other bacteria were enriched under the effect of nicotine, and their DGGE bands changed from undertones to deep colors. The microbial community structure, however, showed a wide variation in the nicotine- contaminated sediment samples, especially in the sediment samples treated with high-concentration nicotine. The Jaccard index was only 35.1% between the initial sediment sample and the sediment sample with a nicotine concentration of 0.030 μg/g after 28 d of exposure. Diversity indices showed that the contaminated groups had a similar trend over time. The diversity indices of contaminated groups all decreased in the first 7 d after exposure, then increased until day 42. It has been found that nicotine decreased the diversity of the microbial community in the sediment.
基金funded by the Project of Science and Technology Department of Shaanxi Province,China(2022NY-074)the National Natural Science Foundation of China(41501255)+1 种基金the Xi'an Science and Technology Project(21NYYF0033)the Fundamental Research Funds for the Central Universities(SYJS202224,GK202206032).
文摘Microorganisms regulate the responses of terrestrial ecosystems to anthropogenic nutrient inputs.The escalation of anthropogenic activities has resulted in a rise in the primary terrestrial constraining elements,namely nitrogen(N)and phosphorus(P).Nevertheless,the specific mechanisms governing the influence of soil microbial community structure and ecological processes in ecologically vulnerable and delicate semi-arid loess agroecosystems remain inadequately understood.Therefore,we explored the effects of different N and P additions on soil microbial community structure and its associated ecological processes in the farmland of Chinese Loess Plateau based on a 36-a long-term experiment.Nine fertilization treatments with complete interactions of high,medium,and low N and P gradients were set up.Soil physical and chemical properties,along with the microbial community structure were measured in this study.Additionally,relevant ecological processes such as microbial biomass,respiration,N mineralization,and enzyme activity were quantified.To elucidate the relationships between these variables,we examined correlation-mediated processes using statistical techniques,including redundancy analysis(RDA)and structural equation modeling(SEM).The results showed that the addition of N alone had a detrimental effect on soil microbial biomass,mineralized N accumulation,andβ-1,4-glucosidase activity.Conversely,the addition of P exhibited an opposing effect,leading to positive influences on these soil parameters.The interactive addition of N and P significantly changed the microbial community structure,increasing microbial activity(microbial biomass and soil respiration),but decreasing the accumulation of mineralized N.Among them,N24P12 treatment showed the greatest increase in the soil nutrient content and respiration.N12P12 treatment increased the overall enzyme activity and total phospholipid fatty acid(PLFA)content by 70.93%.N and P nutrient contents of the soil dominate the microbial community structure and the corresponding changes in hydrolytic enzymes.Soil microbial biomass,respiration,and overall enzyme activity are driven by mineralized N.Our study provides a theoretical basis for exploring energy conversion processes of soil microbial community and environmental sustainability under long-term N and P additions in semi-arid loess areas.
基金Supported by the Suranaree University of Technology and the Higher Education Research Promotionthe National Research University Project of Thailand,Office of the Higher Education Commission
文摘Plant growth-promoting rhizobacteria （PGPR） have been widely recognized as an important agent, especially as a biofertilizer, in agricultural systems. The objectives of this study were to select effective PGPR for Chinese kale （Brassica oleracea var. alboglabra） cultivation and to investigate the effect of their inoculation on indigenous microbial community structure. The Bacillus sp. SUT1 and Pseudomonas sp. SUT19 were selected for determining the efficiency in promoting Chinese kale growth in both pot and field experiments. In the field experiment, PGPR amended with compost gave the highest yields among all treatments. The Chinese kale growth promotion may be directly affected by PGPR inoculation. The changes of microbial community structure in the rhizosphere of Chinese kale following PGPR inoculation were examined by denaturing gradient gel electrophoresis （DGGE） and principal coordinate analysis. The DGGE fingerprints of 16S rDNA amplified from total community DNA in the rhizosphere confirmed that our isolates were established in the rhizosphere throughout this study. The microbial community structures were slightly different among all the treatments, and the major changes depended on stages of plant growth. DNA sequencing of excised DGGE bands showed that the dominant species in microbial community structure in the rhizosphere were not mainly interfered by PGPR, but strongly influenced by plant development. The microbial diversity as revealed by diversity indices was not different between the PGPR-inoculated and uninoculated treatments. In addition, the rhizosphere soil had more influence on eubacterial diversity, whereas it did not affect archaebacterial and fungal diversities.
基金The National Natural Science Foundation of China(No.50909019,51479034)the Fundamental Research Funds for the Central Universities(No.2242019K40064)。
文摘To investigate the effects of silver nanoparticles(Ag NPs)and low temperature double-pressure on the wastewater treatment efficacy and the microbial community structure of constructed wetlands,a pilot-scale vertical flow constructed wetland was set up to treat synthetic wastewater under laboratory conditions.By measuring the effluent concentration of ammonia nitrogen(NH_(4)^(+)-N),total nitrogen(TN),total phosphorus(TP),chemical oxygen demand(COD),and the diversity,richness,and community structure of microorganisms of the upper and lower soil layers in the wetland,the nutrient removal effect of the constructed wetland and the changes in the microflora of the soil layer were studied.The results reveal that the correlation coefficients between the removal rates of TN and NH_(4)^(+)-N and the temperature are 0.463 and 0.692,respectively,indicating a significant positive correlation.From the warm to the cold season,both the diversity and richness of microorganisms in the lower soil layer of wetlands are inhibited under the double-pressure of Ag NPs and low temperature,and the abundances of the denitrogenation functional bacteria such as Candidatus nitrososphaera,Sulfuritalea,Anaeromyxobacter,Candidatus solibacter,Nitrospira,and Zoogloea are altered.Low temperature and Ag NPs exposure can thus affect the wastewater treatment performance of constructed wetlands,possibly because of the seasonal changes of the microflora.
基金supported by the Major Science and Technology Program for Water Pollution Control and Management(No.2013ZX07201007)the State Key Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology(No.2014DX03)the Science Fund for Distinguished Young Scholars of Heilongjiang Province(No.JC201303)
文摘The chemical oxygen demand（COD） and NH3-N removal, membrane fouling, sludge characteristics and microbial community structure in a membrane bioreactor（MBR） coupled with worm reactors（SSBWR） were evaluated for 210 days. The obtained results were compared to those from a conventional MBR（C-MBR） operated in parallel. The results indicated that the combined MBR（S-MBR） achieved higher COD and NH3-N removal efficiency,slower increase in membrane fouling, better sludge settleability and higher activities of the related enzymes in the activated sludge. Denaturing gradient gel electrophoresis was used to analyze the microbial community structures in the C-MBR and the S-MBR. The microbial community structure in the S-MBR was more diverse than that in the C-MBR. Additionally, the slow-growing microbes such as Saprospiraceae, Actinomyces, Frankia, Clostridium, Comamonas,Pseudomonas, Dechloromonas and Flavobacterium were enriched in the S-MBR, further accounting for the sludge reduction, membrane fouling alleviation and wastewater treatment.
基金funded by the National Natural Science Foundation of China(NSFC31301843)the National Nonprofit Institute Research Grant of Chinese Academy of Agricultural Sciences(IARRP-202-5)
文摘Exploration of soil environmental characteristics governing soil microbial community structure and activity may improve our understanding of biogeochemical processes and soil quality. The impact of soil environmental characteristics especially organic carbon availability after 15-yr different organic and inorganic fertilizer inputs on soil bacterial community structure and functional metabolic diversity of soil microbial communities were evaluated in a 15-yr fertilizer experiment in Changping County, Beijing, China. The experiment was a wheat-maize rotation system which was established in 1991 including four different fertilizer treatments. These treatments included： a non-amended control（CK）, a commonly used application rate of inorganic fertilizer treatment（NPK）; a commonly used application rate of inorganic fertilizer with swine manure incorporated treatment（NPKM）, and a commonly used application rate of inorganic fertilizer with maize straw incorporated treatment（NPKS）. Denaturing gradient gel electrophoresis（DGGE） of the 16 S r RNA gene was used to determine the bacterial community structure and single carbon source utilization profiles were determined to characterize the microbial community functional metabolic diversity of different fertilizer treatments using Biolog Eco plates. The results indicated that long-term fertilized treatments significantly increased soil bacterial community structure compared to CK. The use of inorganic fertilizer with organic amendments incorporated for long term（NPKM, NPKS） significantly promoted soil bacterial structure than the application of inorganic fertilizer only（NPK）, and NPKM treatment was the most important driver for increases in the soil microbial community richness（S） and structural diversity（H）. Overall utilization of carbon sources by soil microbial communities（average well color development, AWCD） and microbial substrate utilization diversity and evenness indices（H＇ and E） indicated that long-term inorganic fertilizer with organic amendments incorporated（NPKM, NPKS） could significantly stimulate soil microbial metabolic activity and functional diversity relative to CK, while no differences of them were found between NPKS and NPK treatments. Principal component analysis（PCA） based on carbon source utilization profiles also showed significant separation of soil microbial community under long-term fertilization regimes and NPKM treatment was significantly separated from the other three treatments primarily according to the higher microbial utilization of carbohydrates, carboxylic acids, polymers, phenolic compounds, and amino acid, while higher utilization of amines/amides differed soil microbial community in NPKS treatment from those in the other three treatments. Redundancy analysis（RDA） indicated that soil organic carbon（SOC） availability, especially soil microbial biomass carbon（Cmic） and Cmic/SOC ratio are the key factors of soil environmental characteristics contributing to the increase of both soil microbial community structure and functional metabolic diversity in the long-term fertilization trial. Our results showed that long-term inorganic fertilizer and swine manure application could significantly improve soil bacterial community structure and soil microbial metabolic activity through the increases in SOC availability, which could provide insights into the sustainable management of China＇s soil resource.
