The paper first introduces the definition and classification of plant growth promoting rhizobacteria （PGPR）, then reviews the research achievements on the mechanism of action of plant growth promoting rhizobacteria,...The paper first introduces the definition and classification of plant growth promoting rhizobacteria （PGPR）, then reviews the research achievements on the mechanism of action of plant growth promoting rhizobacteria, including growth pro-moting mechanism and bio-control mechanism, subsequently lists the use of excel-lent plant growth promoting rhizobacteria strains in recent years, especial y Pseu-domonas and Bacil us strains, and final y discusses problems existing in this area and points out issues requiring further exploration, including PGPR screening meth-ods, preservation methods, mechanism of action, in order to commercialize PGPR as soon as possible and practical y realize its application to production.展开更多
To better understand the diversity of metal resistance genetic determinant from microbes that survived at metal tailings in northwest of China, a highly elevated level of heavy metal containing region, genomic analyse...To better understand the diversity of metal resistance genetic determinant from microbes that survived at metal tailings in northwest of China, a highly elevated level of heavy metal containing region, genomic analyses was conducted using genome sequence of three native metal-resistant plant growth promoting bacteria（PGPB）. It shows that： Mesorhizobium amorphae CCNWGS0123 contains metal transporters from P-type ATPase, CDF（Cation Diffusion Facilitator）, Hup E/Ure J and CHR（chromate ion transporter） family involved in copper, zinc, nickel as well as chromate resistance and homeostasis. Meanwhile, the putative Cop A/Cue O system is expected to mediate copper resistance in Sinorhizobium meliloti CCNWSX0020 while Znt A transporter, assisted with putative Czc D, determines zinc tolerance in Agrobacterium tumefaciens CCNWGS0286. The greenhouse experiment provides the consistent evidence of the plant growth promoting effects of these microbes on their hosts by nitrogen fixation and/or indoleacetic acid（IAA） secretion,indicating a potential in-site phytoremediation usage in the mining tailing regions of China.展开更多
Bacillus amyloliquefaciens Bc2 and Trichderma harzianum TR were used to evaluate their growth-promoting activity on cultivated strawberries, under laboratory and field conditions, and we have noticed that the percenta...Bacillus amyloliquefaciens Bc2 and Trichderma harzianum TR were used to evaluate their growth-promoting activity on cultivated strawberries, under laboratory and field conditions, and we have noticed that the percentage of achene germination is important for ones treated with TR (=97%) followed by those treated with Bc2 strain (=90%) and the control (=84%). Inoculations on field showed that on untreated soil with insecticide, TR is effective and allows the development of plants and extends the duration of flowering and fruiting. On treated soil, Bc2 clearly promotes the growth and development of strawberry seedlings and its role as plant growth promoting microorganisms has been proved.展开更多
Aiming at searching for plant growth promoting rhizobacteria (PGPR), a bacterium strain coded as 7016 was isolated from soybean rhizosphere and was characterized in the present study. It was identiifed as Burkholderia...Aiming at searching for plant growth promoting rhizobacteria (PGPR), a bacterium strain coded as 7016 was isolated from soybean rhizosphere and was characterized in the present study. It was identiifed as Burkholderia sp. based on 16S rDNA sequence analysis, as wel as phenotypic and biochemical characterizations. This bacterium presented nitrogenase activity, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity and phosphate solubilizing ability;inhibited the growth of Sclerotinia sclerotiorum, Gibberel a zeae and Verticil ium dahliae;and produced smal quantities of indole acetic acid (IAA). In green house experiments, signiifcant increases in shoot height and weight, root length and weight, and stem diameter were observed on tomato plants in 30 d after inoculation with strain 7016. Result of 16S rDNA PCR-DGGE showed that 7016 survived in the rhizosphere of tomato seedlings. In the ifeld experiments, Burkholderia sp. 7016 enhanced the tomato yield and signiifcantly promoted activities of soil urease, phosphatase, sucrase, and catalase. Al these results demonstrated Burkholderia sp. 7016 as a valuable PGPR and a candidate of biofertilizer.展开更多
Rhizobia are vital for nitrogen input, fertility of soil and legume plant growth. Knowledge on rhizobial diversity from arid and semiarid areas is important for dry land agriculture in the context of climatic change a...Rhizobia are vital for nitrogen input, fertility of soil and legume plant growth. Knowledge on rhizobial diversity from arid and semiarid areas is important for dry land agriculture in the context of climatic change and for economic utilization. This study provides morphological, biochemical, stress tolerance and plant growth promoting characteristics of fifteen rhizobial isolates from the nodules of same number of wild legumes and one isolate from cultivated Arachis hypogea from semi-arid region, Tirupati. The bacterial isolates were confirmed as rhizobia based on colony morphology and biochemical tests. Based on the colour change of YMA-BTB medium, eight isolates were identified as slow growers and six were fast growers. The isolates differed in growth pattern, colony morphology, antibiotic resistance at higher concentrations and uniformity in utilization of carbon and nitrogen sources. The isolates are tolerant to NaCl up to one percent, displayed normal growth at temperatures 28℃ - 30℃, at neutral pH and poor growth at pH 5and 9. The isolates varied in the production of EPS and IAA, positive for phosphate solubilization and siderophore formation. This functional diversity displayed by the isolates can be utilised for the legume crop production by cross inoculation.展开更多
In this study,we proposed a reliable and sustainable technique for the clean utilization of shrimp wastes,which can yield a solid inoculant of Bacillus subtilis OKF04 containing micronutrients at low cost without the ...In this study,we proposed a reliable and sustainable technique for the clean utilization of shrimp wastes,which can yield a solid inoculant of Bacillus subtilis OKF04 containing micronutrients at low cost without the risk of contamination.Study of the culture conditions revealed that the head of shrimp Litopenaus vannamei and the wheat bran acted as suitable substrates for the growth of B.subtilis OKF04.With 60%initial moisture content,30℃culture temperature,and 5%inoculation amount,followed by 48 hours of fermentation and 0.5%soluble starch added during the drying process(50℃for 6h),a solid B.subtilis OKF04 inoculant with a spore amount of 2.4×10^(10)CFU g^(-1)and a high amino acid content was obtained.The solid B.subtilis OKF04 inoculant was applied to cultivate pakchoi under pot experiment.As the result,of adding to,the size of stems and leaves,nutritional composition,and physiological activity of pakchoi were significantly(P<0.05)enhanced by solid B.subtilis OKF04 inoculant.B.subtilis OKF04 also significantly(P<0.05)increased the soil’s nutrient content and improved its microbial composition.Furthermore,pakchoi cultivated with a low dose of solid B.subtilis OKF04 inoculant(0.05 g kg^(-1)soil)resulted in the best results.This study provides a new method for the preparation of microbial inoculants with solid waste shrimp heads.展开更多
[Objectives]To assess the effects of endophytic bacteria on the growth,antioxidant responses,and the production of key secondary metabolites in Emilia prenanthoidea DC.[Methods]Three endophytic strains(H1,H2,L1)were i...[Objectives]To assess the effects of endophytic bacteria on the growth,antioxidant responses,and the production of key secondary metabolites in Emilia prenanthoidea DC.[Methods]Three endophytic strains(H1,H2,L1)were inoculated onto tissue-cultured seedlings and cultivated for 20 d under greenhouse conditions.Growth traits,reactive oxygen species(ROS)indicators,antioxidant enzyme activities,and the content of chlorogenic acid and quercetin were analyzed using one-way ANOVA followed by Tukey s test.[Results]Bacterial inoculation significantly enhanced plant performance.Treatment H2 increased plant height by 27%,chlorophyll content by 73%,and fresh weight by 31%.Levels of ROS(O^(-)_(2),H_(2)O_(2))and MDA decreased markedly,whereas the activities of POD and CAT increased.Additionally,the content of chlorogenic acid and quercetin increased by up to 67%and 64%,respectively,with both H2 and L1 treatments showing the most pronounced effects.[Conclusions]Endophytic bacteria markedly improve growth,redox balance,and phenolic accumulation in E.prenanthoidea.Strain H2 represents a promising bioinoculant for improving the medicinal quality of this species.展开更多
The advancement of life in all its forms relies on agricultural practices and food security,which are fundamentally influenced by soil characteristics.The demand for agricultural products has surged due to climate cha...The advancement of life in all its forms relies on agricultural practices and food security,which are fundamentally influenced by soil characteristics.The demand for agricultural products has surged due to climate change and global population growth,leading to a significant increase in the utilization of chemical fertilizers.Since chemical agents have affected soil fertility and quality by degradation,causing the development of agricultural fields with rich soil to be incomprehensible,consideration for a secure and profitable agricultural production has drifted.Plant growth promoting rhizobacteria(PGPR)have established eco-evolutionary relationships with host plants,fitness,and productivity.Microbial renaissance driven by plant growth regulators has been successfully achieved through disease resistance in emerging pathogens,bio-fertilization,rhizoremediation,and stimulating root growth.PGPR can profoundly increase plant growth by producing growth hormones,improving nutrient uptake,suppressing plant pathogens,and protecting against biotic and abiotic stress conditions.Here,we provide insight into sustainable agricultural development aimed at increasing crop yield and production by exploring the mechanisms and commercial applications of potential rhizobacteria under changing climatic conditions.展开更多
[Objectives]This study was conducted to explore the culture conditions for siderophore production and preliminarily investigate the growth-promoting effects of strains.[Methods]Endophytic bacteria secreting siderophor...[Objectives]This study was conducted to explore the culture conditions for siderophore production and preliminarily investigate the growth-promoting effects of strains.[Methods]Endophytic bacteria secreting siderophores were isolated and screened from the roots of the plant Saposhnikovia divaricata(Trucz.)Schischk.The siderophore-producing capability was confirmed through qualitative detection and gene cluster analysis.[Results]The screened endophytic bacterium PB-2 belonged to the genus Paenibacillus sp.and could produce catechol-type or carboxylate-type siderophores.When cultured in MKB medium with 15 g/L glycerol as the carbon source and 6 g/L glycine as the nitrogen source for 3 d,the strain exhibited efficient siderophore secretion.Appropriate concentrations of Fe^(3+),Co^(2+),Cu^(2+)and Al^(3+)promoted siderophore production,with 15μmol/L Fe^(3+)being the most effective.Under the combined influences of siderophores,volatile compounds and other factors,strain PB-2 altered the root morphology of mulberry seedlings and increased their biomass.The primary root length decreased by 9.15%,while the number and length of root hairs increased by 37.93%and 16.37%,respectively,and the total biomass increased by 10.26%,all showing significant differences(P<0.05).Additionally,strain PB-2 enhanced the activities of defense-related enzymes in mulberry seedling leaves.The activities of superoxide dismutase(SOD)and peroxidase(POD)increased significantly(P<0.05)by 247.27%and 189.47%,respectively,compared with the control group.The activities of phenylalanine ammonialyase(PAL)and polyphenol oxidase(PPO)also showed varying degrees of increase.[Conclusions]This study provided a theoretical basis for rational utilization of endophytic growth-promoting strains secreting siderophores in the sustainable development of agriculture.展开更多
Ferula spp. are traditional medicinal plants found in arid land. Large-scale excavation for extracting bioactive compounds from the plants in arid regions of Xinjiang over the last few years has, however, significandy...Ferula spp. are traditional medicinal plants found in arid land. Large-scale excavation for extracting bioactive compounds from the plants in arid regions of Xinjiang over the last few years has, however, significandy decreased their distributions. Due to the urgent need for preservation of these plant resources, along with the need of searching for alternative source of the useful metabolites, it is important to screen the endophytic microbial resources associated with the plant Ferula sinkiangensis K. M. Shen. In the study, a total of 125 endophytic bacteria belonging to 3 phyla, 13 orders, 23 families, and 29 genera were isolated based on 16S rRNA gene sequencing data. Among the different isolates, three strains isolated from roots were potential novel species of the genera Porphyrobacter, Paracoccus and draycofatopsis. In this study, 79.4% and 57.1% of the total isolates were capable of producing indole-3-acetic acid （IAA） and siderophore, respectively. And, 40.6% of the strains inhibit the growth of fungal pathogen Afternaria alternata, 17.2% and 20.2% strains were positive for antagonism against Vertidllium dahlia 991 and V. dahlia 7, respectively. These results demonstrated that E sinkiangensis is a rich reservoir of endophytic bacterial resources with potential for production of biologically important functions such as plant growth-promoting factors.展开更多
Because of climate change and the highly growing world population,it becomes a huge challenge to feed the whole population.To overcome this challenge and increase the crop yield,a large number of fertilizers are appli...Because of climate change and the highly growing world population,it becomes a huge challenge to feed the whole population.To overcome this challenge and increase the crop yield,a large number of fertilizers are applied but these have many side effects.Instead of these,scientists have discovered beneficial rhizobacteria,which are environmentally friendly and may increase crop yield and plant growth.The microbial population of the rhizosphere shows a pivotal role in plant development by inducing its physiology.Plant depends upon the valuable interactions among the roots and microbes for the growth,nutrients availability,growth promotion,disease suppression and other important roles for plants.Recently numerous secrets of microbes in the rhizosphere have been revealed due to huge development in molecular and microscopic technologies.This review illustrated and discussed the current knowledge on the development,maintenance,interactions of rhizobacterial populations and various proposed mechanisms normally used by PGPR in the rhizosphere that encouraging the plant growth and alleviating the stress conditions.In addition,this research reviewed the role of single and combination of PGPR,mycorrhizal fungi in plant development and modulation of the stress as well as factors affecting the microbiome in the rhizosphere.展开更多
A Plant Biostimulant is any substance or microorganism applied to plants to enhance nutrition efficiency,abioticstress tolerance,and/or crop quality traits,regardless of its nutrient content.The application of Plant b...A Plant Biostimulant is any substance or microorganism applied to plants to enhance nutrition efficiency,abioticstress tolerance,and/or crop quality traits,regardless of its nutrient content.The application of Plant biostimulants(PBs)in production can reduce the application of traditional pesticides and chemical fertilizers and improvethe quality and yield of crops,which is conducive to the sustainable development of agriculture.An in-depthunderstanding of the mechanism and effect of various PBs is very important for how to apply PBs reasonablyand effectively in the practice of crop production.This paper summarizes the main classification of PBs;Thegrowth promotion mechanism of PBs was analyzed from four aspects:improving soil physical and chemical properties,enhancing crop nutrient absorption capacity,photosynthesis capacity,and abiotic stress tolerance;At thesame time,the effects of PBs application on seed germination,seedling vigor,crop yield,and quality were summarized;Finally,how to continue to explore and study the use and mechanism of PBs in the future is analyzedand prospected,to better guide the application of PBs in crop production in the future.展开更多
Chlortetracycline （CTC）, one kind of common antibiotic for prevention and treatment of various diseases, also exhibits good performance in accelerating the growth of livestock. Macleaya cordata, a traditional Chines...Chlortetracycline （CTC）, one kind of common antibiotic for prevention and treatment of various diseases, also exhibits good performance in accelerating the growth of livestock. Macleaya cordata, a traditional Chinese medicine, is usually used as a natural additive in livestock because of its anti-microbial, anti-fungal, anti-inflammatory, and pesticidal activity. In this work, we studied whether M. cordata helps regulate the growth-promoting effect of CTC on broiler chickens. It is demonstrated that M. cordata improves the growth-promoting effect of CTC on growth per- formance indices of broiler chickens, such as survival rate, daily weight, and feed to weight rate. M. cordata also delays the maximum of CTC residues in plasma. It may depend on the higher values of operational taxonomic unit （OTU） and the indices of o diversity driven by simultaneous use of CTC and M. cordata.展开更多
BACKGROUND: The mortality rate of heavy type hepatitisis high. No special treatment is available except generaltreatment. This multicenter clinical study was designed toobserve the safety and efficacy of promoting hep...BACKGROUND: The mortality rate of heavy type hepatitisis high. No special treatment is available except generaltreatment. This multicenter clinical study was designed toobserve the safety and efficacy of promoting hepatic growthfactor (PHGF) in the treatment of heavy type hepatitis andsevere chronic hepatitis.METHODS: 347 patients with heavy type hepatitis and 324with severe chronic hepatitis were subjected to administra-tion of 120 μg of PHGF per day for 4 weeks on the basis ofgeneral treatment. Those who were being effectively treat-ed would last additional 2 to 4 weeks. Blood routine, urineroutine, blood urea nitrogen (BUN), blood creatinine(Cr), blood ammonia, alpha fetoprotein (AFP), electro-lyte, alanine transaminase (ALT), aspartate transaminase(AST), serum total bilirubin (TBIL), serum direct biliru-bin (DBIL), prothrombin time activity (PTA), total pro-tein (TP) and albumin (ALB) were detected in the pa-tients before treatment, 2 weeks after treatment, and at theend of the treatment. Any side-effect would be recorded.RESULTS: In the patients with severe chronic hepatitis, thetotal effective rate of the treatment was 88. 9% The levelsof ALT, AST and TBIL decreased significantly (P<0.001),whereas those of PTA and ALB increased significantly (P <0.001), and the level of AFP increased slightly. In patientswith heavy type hepatitis, the total effective rate of thistreatment was 78.4%, and patients at different stage showeddifferent results. The total effective rates of patients withearly, medium and terminal stage heavy type hepatitis were89.9%, 84.8% and 27.5%, respectively. No severe side-effect was shown.CONCLUSION: PHGF is effective and safe in the treat-ment of patients with heavy type hepatitis and severe chro-nic hepatitis. But it should be administered early in patientswith heavy type hepatitis so as to get better curative effects.展开更多
In this study,pot experiments were conducted on the seedlings of Pinus sylvestris var.mongolica to study the influence of Trichoderma(Trichoderma harzianum E15)and Ectomycorrhizal fungi(Suillus luteus N94)on the growt...In this study,pot experiments were conducted on the seedlings of Pinus sylvestris var.mongolica to study the influence of Trichoderma(Trichoderma harzianum E15)and Ectomycorrhizal fungi(Suillus luteus N94)on the growth of these seedlings.In particular,the effects of these fungi on the fungal community structure in the rhizosphere soil of the seedlings were investigated.Inoculation with Trichoderma harzianum E15 and Suillus luteus N94 significantly(P<0.05)promoted the growth of the Pinus sylvestris seedlings.The non-metric multidimensional scaling(NMDS)results indicated a significant difference(P<0.05)between the fungal community structures in the rhizosphere soil of the annual and biennial seedlings.In the rhizosphere soil of annual seedlings,the main fungi were Ascomycota,Basidiomycota,Zygomycota.Ascomycota,Basidiomycota,Mortierellomycota,and p-unclassified-k-Fungi were the main fungi in the rhizosphere soil of biennial seedlings.The dominant genus in the rhizosphere soil and a key factor promoting the growth of the annual and the biennial seedlings was Trichoderma,Suillus,respectively.Both of them were negatively correlated with the relative abundance of microbial flora in the symbiotic environment.Trichoderma had a significant promoting effect on the conversion of total phosphorus,total nitrogen,ammonium nitrogen,nitrate nitrogen,and the organic matter in the rhizosphere soil of the seedlings,while Suillus significantly promoted the conversion of organic matter and total phosphorus.展开更多
Bacterial endophytes are beneficial to their hosts as they can fix nitrogen in the soil and make it available to the host.Endophytic bacteria also secrete plant growth-promoting hormones to support their host plants u...Bacterial endophytes are beneficial to their hosts as they can fix nitrogen in the soil and make it available to the host.Endophytic bacteria also secrete plant growth-promoting hormones to support their host plants under normal as well as stress conditions.The current study aimed to isolate endophytic bacteria from different parts of Calotropis procera,i.e.,roots,stem and leaves of Calotropis procera(Ait.)W.T.Aiton.Plants were collected from the Lundkhwar,district Mardan.A total of 12 bacterial strains,i.e.,six from roots,three from the stem and three from the leaves were isolated.The strains were screened for their growth-promoting activity in rice plants because rice shows a quick and easy response to the bioactive compounds present in the culture filtrate(CF)of the potent endophytic strains.The rice plants were cultivated in pots containing 30 mL of 0.8%w/v water-agar medium.The pots were placed in a growth chamber,operated at 28±0.3℃ for 14 h(day);and 25±0.3℃ for 10 h(night),at 70%relative-humidity.Among the isolated strains,R1,S1,S3,L1,R5 and R6 showed visible growth promotion in rice plants.The biochemical analysis revealed that the strains were able to produce indole acetic acid(IAA)and flavonoids in higher quantities.Moreover,the strains also produced bioactive compounds that inhibited the growth of Escherichia coli and Aspergillus flavus using the well diffusion method.From the results,it was concluded that these strains can secrete potent compounds that can promote the host plant growth and inhibit the growth of pathogenic microorganisms and,therefore,can be used as bio-fertilizer and bio-control agents.展开更多
This study was conducted to isolate and characterize the plant growth-promoting potential of fungal endophytes from the roots of Diket red,a traditional rice plant from the Cordillera,Northern Luzon.Eighteen morphospe...This study was conducted to isolate and characterize the plant growth-promoting potential of fungal endophytes from the roots of Diket red,a traditional rice plant from the Cordillera,Northern Luzon.Eighteen morphospecies of filamentous endophytes were isolated of which twelve isolates were successfully identified to the species level.These isolates were identified as Aspergillus versicolor,Aspergillus sp.,Chaetosphaeria sp.,Cladosporium cladosporioides,Hypocrea lixii,Microascus murinus,and Trichoderma harzianum.The identified twelve isolates were selected to screen in vitro for their plant growth-promoting characteristics,and evaluated in vivo for their beneficial effects on seedling vigor and early seedling growth.Isolate PPL14 produced the highest IAA at 55.5μg ml^(-1)and M.murinus PPL10 produced the highest amount of IAA at 3.73μg IAA mg^(-1)dry mycelia wt.The seedling vigor assay and in vivo plant growth promotion bioassay indicated overall positive effects of culture filtrate(CF)application of the endophyte isolates.Rice seeds and seedlings grown in aseptic condition and treated with endophyte CFs displayed significantly enhanced levels of germination,seedling vigor,shoot,root,and total plant growth,and biomass compared to non-treated control.Other plant growth-promoting characteristics were also studied including phosphate solubilization,siderophore production,ammonia production,and catalase activity.This study supports the potential use of fungal endophytes as bio-inoculants for plant growth promotion and enhancement of nutrient assimilation of agriculturally important crops.展开更多
Microorganisms inhabiting soils contaminated with heavy metals produce melanin,a dark brown pigment,as a survival strategy.In this study,a melanin-producing bacterium,Acinetobacter sp.ME1,with heavy metal tolerance an...Microorganisms inhabiting soils contaminated with heavy metals produce melanin,a dark brown pigment,as a survival strategy.In this study,a melanin-producing bacterium,Acinetobacter sp.ME1,with heavy metal tolerance and plant growth-promoting traits,was isolated from abandoned mine soil.Strain ME1 exhibited growth at concentrations of Zn up to 250 mg/L,Cd and Pb up to 100 mg/L,and Cr up to 50 mg/L.It had the ability to produce the plant hormone indole-3-acetic acid and siderophores along with 1-aminocyclopropane-1-carboxylic acid deaminase and protease activities.Additionally,it showed antioxidant activity,including catalase and 2,2-diphenyl-1-picryhydrazyl(DPPH)scavenging activities.The optimal conditions for melanin production by ME1 were a pH of 7 and a temperature of 35℃.At 1000 mg/L,ME1-extracted melanin exhibited DPPH radical scavenging activity of(25.040±0.007)%,a sun protection factor of 15.200±0.260,and 19.6%antibacterial activity against the plant pathogen Xanthomonas campestris.Furthermore,its adsorption capacity was(0.235±0.073)mg/g melanin for Zn and(0.277±0.008)mg/g melanin for Ni.In plants of Brassica chinensis grown under conditions of hydroponic cultivation with single heavy metal contamination of Cd,Zn,Pb,or Cr,the removal efficiency of each heavy metal was improved by 0.1–1.8 times after 3 d following inoculation with the strain ME1 compared to the plants grown under the same conditions without inoculation.In addition,ME1 inoculation improved the removal efficiency of each heavy metal by 0.1–1.0 times under multiple heavy metal contamination conditions.These findings suggest that Acinetobacter sp.ME1 could be used to enhance phytoremediation efficiency in heavy metal-contaminated soils.Moreover,the melanin it produces also holds promise in cosmetics,household products,and medical applications due to its photoprotective,antioxidant,and antimicrobial properties.展开更多
Sediment properties have a crucial effect on the growth and recovery of aquatic plants in lakes.Addition of various chemical substances has been proposed to reinforce the recovery of plants after a nutrient loading re...Sediment properties have a crucial effect on the growth and recovery of aquatic plants in lakes.Addition of various chemical substances has been proposed to reinforce the recovery of plants after a nutrient loading reduction.However,the effects of such sediment amendments on plant growth,especially those from rhizosphere microorganisms,is limited.We added Kaolin clay to sediments in different concentrations to explore its impact on the growth of Vallisneria natans and Ottelia acuminate and the concurrent shift in rhizosphere microorganisms using high-throughput sequencing technology.We found that the addition of low doses(10%and 20%in mass ratio)of Kaolin significantly modified sediment conditions(oxidation reduction potential and pH),with implications also for the composition,diversity,and stability of rhizosphere microorganisms.LEfSe analysis revealed that low-dose addition of Kaolin increased the abundances of functional microbial groups that benefit plant nutrient absorption and enhance plant stress resistance,such as Spirillaceae,Rhodocyclaceae,and Burkholderiales.Moreover,low doses of Kaolin significantly promoted the photosynthesis and nutrient absorption of submerged macrophytes,thereby facilitating plant growth.A structural equation model(SEM)indicated that the direct impact of Kaolin on the growth of submerged plants was relatively minor,while the indirect effect through modulation of rhizosphere microorganisms was important.Our study suggests that low doses of Kaolin may be used to promote the growth of submerged macrophytes when lakes with a high organic content in the sediment are recovering after nutrient loading reduction.展开更多
The exopolysaccharide matrix of diazotrophic cyanobacteria was used to integrate phosphorus(P)and potassium(K)solubilizing bacteria,enhancing the survival of plant growth-promoting rhizobacteria,and ultimately the sur...The exopolysaccharide matrix of diazotrophic cyanobacteria was used to integrate phosphorus(P)and potassium(K)solubilizing bacteria,enhancing the survival of plant growth-promoting rhizobacteria,and ultimately the survival of bacteria in the rhizosphere for better plant growth.A new biofilm-based formulation comprising the diazotrophic cyanobacteria Anabaena AMP2,P-solubilizing Bacillus megaterium var.phosphaticum PB1,and K-solubilizing Rhizobium pusense KRBKKM1 was tested for efficacy in rice.The growth medium with half-strength BG-11 medium supplemented with 3%glucose showed best for biofilm formation under in vitro conditions.Analysis of the methanolic extract of the cyanobacterial-bacterial biofilm(CBB)showed the activity of antioxidants,such as 2-methoxy phenol and pentadecane,which are proven to improve plant-microbe interactions and plant growth,respectively.Treatment of rice seeds with CBB extract at 100 mL/kg or 200 mL/kg showed significant enhancement in germination rate and seedling length.Therefore,a pot culture experiment with the CBB formulations was carried out,and different growth and yield parameters were recorded.Principal component analysis showed that plant growth,yield,soil dehydrogenase activity,and soil chlorophyll content were positively correlated with rice plants amended with vermiculite-based CBB at 2 kg/hm^(2) followed by a spray with aqueous CBB formulation at 5 mL/L at 15 and 30 d after rice transplanting grown with a 25%reduced level of nitrogen/phosphorus/potassium chemical fertilizers than the recommended dose.Further,Pearson correlation analysis showed that yield was positively correlated with soil dehydrogenase(r=0.92**)and soil chlorophyll content(r=0.96**).We concluded that CBB could be used as a novel biofilm-based bio-inoculant to increase rice productivity and crop fitness as a component in integrated nutrient management and sustainable organic farming strategies with reduced chemical fertilizers.展开更多
基金Supported by the Science and Technology Project of Nanping Tobacco Company(201203)~~
文摘The paper first introduces the definition and classification of plant growth promoting rhizobacteria （PGPR）, then reviews the research achievements on the mechanism of action of plant growth promoting rhizobacteria, including growth pro-moting mechanism and bio-control mechanism, subsequently lists the use of excel-lent plant growth promoting rhizobacteria strains in recent years, especial y Pseu-domonas and Bacil us strains, and final y discusses problems existing in this area and points out issues requiring further exploration, including PGPR screening meth-ods, preservation methods, mechanism of action, in order to commercialize PGPR as soon as possible and practical y realize its application to production.
基金supported by the National High Technology Research and Development Program (863) of China (No.2012AA101402)the National Science Foundation of China (Nos.31125007,31370142)
文摘To better understand the diversity of metal resistance genetic determinant from microbes that survived at metal tailings in northwest of China, a highly elevated level of heavy metal containing region, genomic analyses was conducted using genome sequence of three native metal-resistant plant growth promoting bacteria（PGPB）. It shows that： Mesorhizobium amorphae CCNWGS0123 contains metal transporters from P-type ATPase, CDF（Cation Diffusion Facilitator）, Hup E/Ure J and CHR（chromate ion transporter） family involved in copper, zinc, nickel as well as chromate resistance and homeostasis. Meanwhile, the putative Cop A/Cue O system is expected to mediate copper resistance in Sinorhizobium meliloti CCNWSX0020 while Znt A transporter, assisted with putative Czc D, determines zinc tolerance in Agrobacterium tumefaciens CCNWGS0286. The greenhouse experiment provides the consistent evidence of the plant growth promoting effects of these microbes on their hosts by nitrogen fixation and/or indoleacetic acid（IAA） secretion,indicating a potential in-site phytoremediation usage in the mining tailing regions of China.
文摘Bacillus amyloliquefaciens Bc2 and Trichderma harzianum TR were used to evaluate their growth-promoting activity on cultivated strawberries, under laboratory and field conditions, and we have noticed that the percentage of achene germination is important for ones treated with TR (=97%) followed by those treated with Bc2 strain (=90%) and the control (=84%). Inoculations on field showed that on untreated soil with insecticide, TR is effective and allows the development of plants and extends the duration of flowering and fruiting. On treated soil, Bc2 clearly promotes the growth and development of strawberry seedlings and its role as plant growth promoting microorganisms has been proved.
基金supported by the National Natural Science Foundation of China (31100364)the National Nonprofit Institute Research Grant of Chinese Academy of Agricultural Sciences (CAAS, IARRP-2014-20)
文摘Aiming at searching for plant growth promoting rhizobacteria (PGPR), a bacterium strain coded as 7016 was isolated from soybean rhizosphere and was characterized in the present study. It was identiifed as Burkholderia sp. based on 16S rDNA sequence analysis, as wel as phenotypic and biochemical characterizations. This bacterium presented nitrogenase activity, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity and phosphate solubilizing ability;inhibited the growth of Sclerotinia sclerotiorum, Gibberel a zeae and Verticil ium dahliae;and produced smal quantities of indole acetic acid (IAA). In green house experiments, signiifcant increases in shoot height and weight, root length and weight, and stem diameter were observed on tomato plants in 30 d after inoculation with strain 7016. Result of 16S rDNA PCR-DGGE showed that 7016 survived in the rhizosphere of tomato seedlings. In the ifeld experiments, Burkholderia sp. 7016 enhanced the tomato yield and signiifcantly promoted activities of soil urease, phosphatase, sucrase, and catalase. Al these results demonstrated Burkholderia sp. 7016 as a valuable PGPR and a candidate of biofertilizer.
文摘Rhizobia are vital for nitrogen input, fertility of soil and legume plant growth. Knowledge on rhizobial diversity from arid and semiarid areas is important for dry land agriculture in the context of climatic change and for economic utilization. This study provides morphological, biochemical, stress tolerance and plant growth promoting characteristics of fifteen rhizobial isolates from the nodules of same number of wild legumes and one isolate from cultivated Arachis hypogea from semi-arid region, Tirupati. The bacterial isolates were confirmed as rhizobia based on colony morphology and biochemical tests. Based on the colour change of YMA-BTB medium, eight isolates were identified as slow growers and six were fast growers. The isolates differed in growth pattern, colony morphology, antibiotic resistance at higher concentrations and uniformity in utilization of carbon and nitrogen sources. The isolates are tolerant to NaCl up to one percent, displayed normal growth at temperatures 28℃ - 30℃, at neutral pH and poor growth at pH 5and 9. The isolates varied in the production of EPS and IAA, positive for phosphate solubilization and siderophore formation. This functional diversity displayed by the isolates can be utilised for the legume crop production by cross inoculation.
基金the China Agriculture Research System of MOF and MARA(No.CARS-48)the Taishan Scholar Project of Shandong Province(No.tsqn201812020)。
文摘In this study,we proposed a reliable and sustainable technique for the clean utilization of shrimp wastes,which can yield a solid inoculant of Bacillus subtilis OKF04 containing micronutrients at low cost without the risk of contamination.Study of the culture conditions revealed that the head of shrimp Litopenaus vannamei and the wheat bran acted as suitable substrates for the growth of B.subtilis OKF04.With 60%initial moisture content,30℃culture temperature,and 5%inoculation amount,followed by 48 hours of fermentation and 0.5%soluble starch added during the drying process(50℃for 6h),a solid B.subtilis OKF04 inoculant with a spore amount of 2.4×10^(10)CFU g^(-1)and a high amino acid content was obtained.The solid B.subtilis OKF04 inoculant was applied to cultivate pakchoi under pot experiment.As the result,of adding to,the size of stems and leaves,nutritional composition,and physiological activity of pakchoi were significantly(P<0.05)enhanced by solid B.subtilis OKF04 inoculant.B.subtilis OKF04 also significantly(P<0.05)increased the soil’s nutrient content and improved its microbial composition.Furthermore,pakchoi cultivated with a low dose of solid B.subtilis OKF04 inoculant(0.05 g kg^(-1)soil)resulted in the best results.This study provides a new method for the preparation of microbial inoculants with solid waste shrimp heads.
文摘[Objectives]To assess the effects of endophytic bacteria on the growth,antioxidant responses,and the production of key secondary metabolites in Emilia prenanthoidea DC.[Methods]Three endophytic strains(H1,H2,L1)were inoculated onto tissue-cultured seedlings and cultivated for 20 d under greenhouse conditions.Growth traits,reactive oxygen species(ROS)indicators,antioxidant enzyme activities,and the content of chlorogenic acid and quercetin were analyzed using one-way ANOVA followed by Tukey s test.[Results]Bacterial inoculation significantly enhanced plant performance.Treatment H2 increased plant height by 27%,chlorophyll content by 73%,and fresh weight by 31%.Levels of ROS(O^(-)_(2),H_(2)O_(2))and MDA decreased markedly,whereas the activities of POD and CAT increased.Additionally,the content of chlorogenic acid and quercetin increased by up to 67%and 64%,respectively,with both H2 and L1 treatments showing the most pronounced effects.[Conclusions]Endophytic bacteria markedly improve growth,redox balance,and phenolic accumulation in E.prenanthoidea.Strain H2 represents a promising bioinoculant for improving the medicinal quality of this species.
基金supported by the Yunnan Agricultural University Startup Fund(20232020003).
文摘The advancement of life in all its forms relies on agricultural practices and food security,which are fundamentally influenced by soil characteristics.The demand for agricultural products has surged due to climate change and global population growth,leading to a significant increase in the utilization of chemical fertilizers.Since chemical agents have affected soil fertility and quality by degradation,causing the development of agricultural fields with rich soil to be incomprehensible,consideration for a secure and profitable agricultural production has drifted.Plant growth promoting rhizobacteria(PGPR)have established eco-evolutionary relationships with host plants,fitness,and productivity.Microbial renaissance driven by plant growth regulators has been successfully achieved through disease resistance in emerging pathogens,bio-fertilization,rhizoremediation,and stimulating root growth.PGPR can profoundly increase plant growth by producing growth hormones,improving nutrient uptake,suppressing plant pathogens,and protecting against biotic and abiotic stress conditions.Here,we provide insight into sustainable agricultural development aimed at increasing crop yield and production by exploring the mechanisms and commercial applications of potential rhizobacteria under changing climatic conditions.
基金Supported by Doctoral Start-up Fund of Jiangsu University of Science and Technology(1102931901).
文摘[Objectives]This study was conducted to explore the culture conditions for siderophore production and preliminarily investigate the growth-promoting effects of strains.[Methods]Endophytic bacteria secreting siderophores were isolated and screened from the roots of the plant Saposhnikovia divaricata(Trucz.)Schischk.The siderophore-producing capability was confirmed through qualitative detection and gene cluster analysis.[Results]The screened endophytic bacterium PB-2 belonged to the genus Paenibacillus sp.and could produce catechol-type or carboxylate-type siderophores.When cultured in MKB medium with 15 g/L glycerol as the carbon source and 6 g/L glycine as the nitrogen source for 3 d,the strain exhibited efficient siderophore secretion.Appropriate concentrations of Fe^(3+),Co^(2+),Cu^(2+)and Al^(3+)promoted siderophore production,with 15μmol/L Fe^(3+)being the most effective.Under the combined influences of siderophores,volatile compounds and other factors,strain PB-2 altered the root morphology of mulberry seedlings and increased their biomass.The primary root length decreased by 9.15%,while the number and length of root hairs increased by 37.93%and 16.37%,respectively,and the total biomass increased by 10.26%,all showing significant differences(P<0.05).Additionally,strain PB-2 enhanced the activities of defense-related enzymes in mulberry seedling leaves.The activities of superoxide dismutase(SOD)and peroxidase(POD)increased significantly(P<0.05)by 247.27%and 189.47%,respectively,compared with the control group.The activities of phenylalanine ammonialyase(PAL)and polyphenol oxidase(PPO)also showed varying degrees of increase.[Conclusions]This study provided a theoretical basis for rational utilization of endophytic growth-promoting strains secreting siderophores in the sustainable development of agriculture.
基金supported by the National Natural Science Foundation of China(U1403101,31200008)the China Postdoctoral Science Foundation(2016M602566)+3 种基金the Visiting Scholar Grant of State Key Laboratory of Biocontrol,Sun Yat-Sen University(SKLBC14F02)the West Light Foundation of the Chinese Academy of Sciencessupported by Hundred Talents Program of the Chinese Academy of SciencesGuangdong Province Higher Vocational Colleges & Schools Pearl River Scholar Funded Scheme(2014)
文摘Ferula spp. are traditional medicinal plants found in arid land. Large-scale excavation for extracting bioactive compounds from the plants in arid regions of Xinjiang over the last few years has, however, significandy decreased their distributions. Due to the urgent need for preservation of these plant resources, along with the need of searching for alternative source of the useful metabolites, it is important to screen the endophytic microbial resources associated with the plant Ferula sinkiangensis K. M. Shen. In the study, a total of 125 endophytic bacteria belonging to 3 phyla, 13 orders, 23 families, and 29 genera were isolated based on 16S rRNA gene sequencing data. Among the different isolates, three strains isolated from roots were potential novel species of the genera Porphyrobacter, Paracoccus and draycofatopsis. In this study, 79.4% and 57.1% of the total isolates were capable of producing indole-3-acetic acid （IAA） and siderophore, respectively. And, 40.6% of the strains inhibit the growth of fungal pathogen Afternaria alternata, 17.2% and 20.2% strains were positive for antagonism against Vertidllium dahlia 991 and V. dahlia 7, respectively. These results demonstrated that E sinkiangensis is a rich reservoir of endophytic bacterial resources with potential for production of biologically important functions such as plant growth-promoting factors.
基金The authors acknowledge that this work was financially supported by the Fundamental Research Fund for the Central Universities of China(Project No.lzujbky-2017-k15).
文摘Because of climate change and the highly growing world population,it becomes a huge challenge to feed the whole population.To overcome this challenge and increase the crop yield,a large number of fertilizers are applied but these have many side effects.Instead of these,scientists have discovered beneficial rhizobacteria,which are environmentally friendly and may increase crop yield and plant growth.The microbial population of the rhizosphere shows a pivotal role in plant development by inducing its physiology.Plant depends upon the valuable interactions among the roots and microbes for the growth,nutrients availability,growth promotion,disease suppression and other important roles for plants.Recently numerous secrets of microbes in the rhizosphere have been revealed due to huge development in molecular and microscopic technologies.This review illustrated and discussed the current knowledge on the development,maintenance,interactions of rhizobacterial populations and various proposed mechanisms normally used by PGPR in the rhizosphere that encouraging the plant growth and alleviating the stress conditions.In addition,this research reviewed the role of single and combination of PGPR,mycorrhizal fungi in plant development and modulation of the stress as well as factors affecting the microbiome in the rhizosphere.
基金the National Natural Science Foundation of China(No.32001984).
文摘A Plant Biostimulant is any substance or microorganism applied to plants to enhance nutrition efficiency,abioticstress tolerance,and/or crop quality traits,regardless of its nutrient content.The application of Plant biostimulants(PBs)in production can reduce the application of traditional pesticides and chemical fertilizers and improvethe quality and yield of crops,which is conducive to the sustainable development of agriculture.An in-depthunderstanding of the mechanism and effect of various PBs is very important for how to apply PBs reasonablyand effectively in the practice of crop production.This paper summarizes the main classification of PBs;Thegrowth promotion mechanism of PBs was analyzed from four aspects:improving soil physical and chemical properties,enhancing crop nutrient absorption capacity,photosynthesis capacity,and abiotic stress tolerance;At thesame time,the effects of PBs application on seed germination,seedling vigor,crop yield,and quality were summarized;Finally,how to continue to explore and study the use and mechanism of PBs in the future is analyzedand prospected,to better guide the application of PBs in crop production in the future.
基金Project supported by the Natural Science Foundation of Jiangsu Province for Excellent Young Scholars(No.BK20170087)the National Natural Science Foundation of China(Nos.31502033,31472164,and 31672515)
文摘Chlortetracycline （CTC）, one kind of common antibiotic for prevention and treatment of various diseases, also exhibits good performance in accelerating the growth of livestock. Macleaya cordata, a traditional Chinese medicine, is usually used as a natural additive in livestock because of its anti-microbial, anti-fungal, anti-inflammatory, and pesticidal activity. In this work, we studied whether M. cordata helps regulate the growth-promoting effect of CTC on broiler chickens. It is demonstrated that M. cordata improves the growth-promoting effect of CTC on growth per- formance indices of broiler chickens, such as survival rate, daily weight, and feed to weight rate. M. cordata also delays the maximum of CTC residues in plasma. It may depend on the higher values of operational taxonomic unit （OTU） and the indices of o diversity driven by simultaneous use of CTC and M. cordata.
文摘BACKGROUND: The mortality rate of heavy type hepatitisis high. No special treatment is available except generaltreatment. This multicenter clinical study was designed toobserve the safety and efficacy of promoting hepatic growthfactor (PHGF) in the treatment of heavy type hepatitis andsevere chronic hepatitis.METHODS: 347 patients with heavy type hepatitis and 324with severe chronic hepatitis were subjected to administra-tion of 120 μg of PHGF per day for 4 weeks on the basis ofgeneral treatment. Those who were being effectively treat-ed would last additional 2 to 4 weeks. Blood routine, urineroutine, blood urea nitrogen (BUN), blood creatinine(Cr), blood ammonia, alpha fetoprotein (AFP), electro-lyte, alanine transaminase (ALT), aspartate transaminase(AST), serum total bilirubin (TBIL), serum direct biliru-bin (DBIL), prothrombin time activity (PTA), total pro-tein (TP) and albumin (ALB) were detected in the pa-tients before treatment, 2 weeks after treatment, and at theend of the treatment. Any side-effect would be recorded.RESULTS: In the patients with severe chronic hepatitis, thetotal effective rate of the treatment was 88. 9% The levelsof ALT, AST and TBIL decreased significantly (P<0.001),whereas those of PTA and ALB increased significantly (P <0.001), and the level of AFP increased slightly. In patientswith heavy type hepatitis, the total effective rate of thistreatment was 78.4%, and patients at different stage showeddifferent results. The total effective rates of patients withearly, medium and terminal stage heavy type hepatitis were89.9%, 84.8% and 27.5%, respectively. No severe side-effect was shown.CONCLUSION: PHGF is effective and safe in the treat-ment of patients with heavy type hepatitis and severe chro-nic hepatitis. But it should be administered early in patientswith heavy type hepatitis so as to get better curative effects.
文摘In this study,pot experiments were conducted on the seedlings of Pinus sylvestris var.mongolica to study the influence of Trichoderma(Trichoderma harzianum E15)and Ectomycorrhizal fungi(Suillus luteus N94)on the growth of these seedlings.In particular,the effects of these fungi on the fungal community structure in the rhizosphere soil of the seedlings were investigated.Inoculation with Trichoderma harzianum E15 and Suillus luteus N94 significantly(P<0.05)promoted the growth of the Pinus sylvestris seedlings.The non-metric multidimensional scaling(NMDS)results indicated a significant difference(P<0.05)between the fungal community structures in the rhizosphere soil of the annual and biennial seedlings.In the rhizosphere soil of annual seedlings,the main fungi were Ascomycota,Basidiomycota,Zygomycota.Ascomycota,Basidiomycota,Mortierellomycota,and p-unclassified-k-Fungi were the main fungi in the rhizosphere soil of biennial seedlings.The dominant genus in the rhizosphere soil and a key factor promoting the growth of the annual and the biennial seedlings was Trichoderma,Suillus,respectively.Both of them were negatively correlated with the relative abundance of microbial flora in the symbiotic environment.Trichoderma had a significant promoting effect on the conversion of total phosphorus,total nitrogen,ammonium nitrogen,nitrate nitrogen,and the organic matter in the rhizosphere soil of the seedlings,while Suillus significantly promoted the conversion of organic matter and total phosphorus.
基金This research was supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(2017R1D1A1B04035601).
文摘Bacterial endophytes are beneficial to their hosts as they can fix nitrogen in the soil and make it available to the host.Endophytic bacteria also secrete plant growth-promoting hormones to support their host plants under normal as well as stress conditions.The current study aimed to isolate endophytic bacteria from different parts of Calotropis procera,i.e.,roots,stem and leaves of Calotropis procera(Ait.)W.T.Aiton.Plants were collected from the Lundkhwar,district Mardan.A total of 12 bacterial strains,i.e.,six from roots,three from the stem and three from the leaves were isolated.The strains were screened for their growth-promoting activity in rice plants because rice shows a quick and easy response to the bioactive compounds present in the culture filtrate(CF)of the potent endophytic strains.The rice plants were cultivated in pots containing 30 mL of 0.8%w/v water-agar medium.The pots were placed in a growth chamber,operated at 28±0.3℃ for 14 h(day);and 25±0.3℃ for 10 h(night),at 70%relative-humidity.Among the isolated strains,R1,S1,S3,L1,R5 and R6 showed visible growth promotion in rice plants.The biochemical analysis revealed that the strains were able to produce indole acetic acid(IAA)and flavonoids in higher quantities.Moreover,the strains also produced bioactive compounds that inhibited the growth of Escherichia coli and Aspergillus flavus using the well diffusion method.From the results,it was concluded that these strains can secrete potent compounds that can promote the host plant growth and inhibit the growth of pathogenic microorganisms and,therefore,can be used as bio-fertilizer and bio-control agents.
基金This project is supported by a Junior Thesis Fellowship Grant awarded to the authors by the Philippine Rice Research Institute(PhilRice).
文摘This study was conducted to isolate and characterize the plant growth-promoting potential of fungal endophytes from the roots of Diket red,a traditional rice plant from the Cordillera,Northern Luzon.Eighteen morphospecies of filamentous endophytes were isolated of which twelve isolates were successfully identified to the species level.These isolates were identified as Aspergillus versicolor,Aspergillus sp.,Chaetosphaeria sp.,Cladosporium cladosporioides,Hypocrea lixii,Microascus murinus,and Trichoderma harzianum.The identified twelve isolates were selected to screen in vitro for their plant growth-promoting characteristics,and evaluated in vivo for their beneficial effects on seedling vigor and early seedling growth.Isolate PPL14 produced the highest IAA at 55.5μg ml^(-1)and M.murinus PPL10 produced the highest amount of IAA at 3.73μg IAA mg^(-1)dry mycelia wt.The seedling vigor assay and in vivo plant growth promotion bioassay indicated overall positive effects of culture filtrate(CF)application of the endophyte isolates.Rice seeds and seedlings grown in aseptic condition and treated with endophyte CFs displayed significantly enhanced levels of germination,seedling vigor,shoot,root,and total plant growth,and biomass compared to non-treated control.Other plant growth-promoting characteristics were also studied including phosphate solubilization,siderophore production,ammonia production,and catalase activity.This study supports the potential use of fungal endophytes as bio-inoculants for plant growth promotion and enhancement of nutrient assimilation of agriculturally important crops.
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Korean government,the Ministry of Science,and the Ministry of Science and Information and Communication Technology(ICT(MSIT))(Nos.2022R1A2C2006615 and RS2023-00217228).
文摘Microorganisms inhabiting soils contaminated with heavy metals produce melanin,a dark brown pigment,as a survival strategy.In this study,a melanin-producing bacterium,Acinetobacter sp.ME1,with heavy metal tolerance and plant growth-promoting traits,was isolated from abandoned mine soil.Strain ME1 exhibited growth at concentrations of Zn up to 250 mg/L,Cd and Pb up to 100 mg/L,and Cr up to 50 mg/L.It had the ability to produce the plant hormone indole-3-acetic acid and siderophores along with 1-aminocyclopropane-1-carboxylic acid deaminase and protease activities.Additionally,it showed antioxidant activity,including catalase and 2,2-diphenyl-1-picryhydrazyl(DPPH)scavenging activities.The optimal conditions for melanin production by ME1 were a pH of 7 and a temperature of 35℃.At 1000 mg/L,ME1-extracted melanin exhibited DPPH radical scavenging activity of(25.040±0.007)%,a sun protection factor of 15.200±0.260,and 19.6%antibacterial activity against the plant pathogen Xanthomonas campestris.Furthermore,its adsorption capacity was(0.235±0.073)mg/g melanin for Zn and(0.277±0.008)mg/g melanin for Ni.In plants of Brassica chinensis grown under conditions of hydroponic cultivation with single heavy metal contamination of Cd,Zn,Pb,or Cr,the removal efficiency of each heavy metal was improved by 0.1–1.8 times after 3 d following inoculation with the strain ME1 compared to the plants grown under the same conditions without inoculation.In addition,ME1 inoculation improved the removal efficiency of each heavy metal by 0.1–1.0 times under multiple heavy metal contamination conditions.These findings suggest that Acinetobacter sp.ME1 could be used to enhance phytoremediation efficiency in heavy metal-contaminated soils.Moreover,the melanin it produces also holds promise in cosmetics,household products,and medical applications due to its photoprotective,antioxidant,and antimicrobial properties.
基金supported by the National Natural Science Foundation of China(Nos.U23A20153,and 32101319).
文摘Sediment properties have a crucial effect on the growth and recovery of aquatic plants in lakes.Addition of various chemical substances has been proposed to reinforce the recovery of plants after a nutrient loading reduction.However,the effects of such sediment amendments on plant growth,especially those from rhizosphere microorganisms,is limited.We added Kaolin clay to sediments in different concentrations to explore its impact on the growth of Vallisneria natans and Ottelia acuminate and the concurrent shift in rhizosphere microorganisms using high-throughput sequencing technology.We found that the addition of low doses(10%and 20%in mass ratio)of Kaolin significantly modified sediment conditions(oxidation reduction potential and pH),with implications also for the composition,diversity,and stability of rhizosphere microorganisms.LEfSe analysis revealed that low-dose addition of Kaolin increased the abundances of functional microbial groups that benefit plant nutrient absorption and enhance plant stress resistance,such as Spirillaceae,Rhodocyclaceae,and Burkholderiales.Moreover,low doses of Kaolin significantly promoted the photosynthesis and nutrient absorption of submerged macrophytes,thereby facilitating plant growth.A structural equation model(SEM)indicated that the direct impact of Kaolin on the growth of submerged plants was relatively minor,while the indirect effect through modulation of rhizosphere microorganisms was important.Our study suggests that low doses of Kaolin may be used to promote the growth of submerged macrophytes when lakes with a high organic content in the sediment are recovering after nutrient loading reduction.
基金supported by the Researchers Supporting Project of King Saud University,Riyadh,Saudi Arabia(Grant No.RSP2025R358)Tamil Nadu Agricultural University,Coimbatore,India(Grant No.NRM-MDU-AGM-14-006).
文摘The exopolysaccharide matrix of diazotrophic cyanobacteria was used to integrate phosphorus(P)and potassium(K)solubilizing bacteria,enhancing the survival of plant growth-promoting rhizobacteria,and ultimately the survival of bacteria in the rhizosphere for better plant growth.A new biofilm-based formulation comprising the diazotrophic cyanobacteria Anabaena AMP2,P-solubilizing Bacillus megaterium var.phosphaticum PB1,and K-solubilizing Rhizobium pusense KRBKKM1 was tested for efficacy in rice.The growth medium with half-strength BG-11 medium supplemented with 3%glucose showed best for biofilm formation under in vitro conditions.Analysis of the methanolic extract of the cyanobacterial-bacterial biofilm(CBB)showed the activity of antioxidants,such as 2-methoxy phenol and pentadecane,which are proven to improve plant-microbe interactions and plant growth,respectively.Treatment of rice seeds with CBB extract at 100 mL/kg or 200 mL/kg showed significant enhancement in germination rate and seedling length.Therefore,a pot culture experiment with the CBB formulations was carried out,and different growth and yield parameters were recorded.Principal component analysis showed that plant growth,yield,soil dehydrogenase activity,and soil chlorophyll content were positively correlated with rice plants amended with vermiculite-based CBB at 2 kg/hm^(2) followed by a spray with aqueous CBB formulation at 5 mL/L at 15 and 30 d after rice transplanting grown with a 25%reduced level of nitrogen/phosphorus/potassium chemical fertilizers than the recommended dose.Further,Pearson correlation analysis showed that yield was positively correlated with soil dehydrogenase(r=0.92**)and soil chlorophyll content(r=0.96**).We concluded that CBB could be used as a novel biofilm-based bio-inoculant to increase rice productivity and crop fitness as a component in integrated nutrient management and sustainable organic farming strategies with reduced chemical fertilizers.
