In Burkina Faso, as in other African countries, infertility has become a social burden for the population and a public health problem. Male infertility accounts for 30% to 40% of all infertility cases. The diagnosis o...In Burkina Faso, as in other African countries, infertility has become a social burden for the population and a public health problem. Male infertility accounts for 30% to 40% of all infertility cases. The diagnosis of male infertility or hypofertility is often made by a simple laboratory analysis of sperm to explore sperm parameters. In most African countries, such as Burkina Faso, microbiological analysis in the context of sperm analysis is still not developed, and is carried out solely based on microscopy and traditional culture, which does not allow the growth of fragile and demanding bacteria. Our study investigated the microorganisms of sperm that may be involved in male infertility, using conventional bacteriology techniques and real-time PCR. However, it did not intend to perform a multivariate statistical association analysis to estimate the association of microorganisms with abnormal semen parameters. This prospective cross-sectional pilot study was carried out on patients who visited the bacteriology laboratory of Centre MURAZ, a research Institute in Burkina Faso, for male infertility diagnosis between 2 August and 31 August 2021. Bacteria were isolated and identified using standard bacteriology techniques. In parallel, common pathogenic microorganisms known to be associated with male infertility were targeted and detected in the sperm using a multiplex real-time PCR assay. A total of 38 sperm samples were analyzed by bacteriological culture and bacteria isolated were Staphylococcus aureus (S. aureus) 5.55%, Klebsiella pneumoniae (K. pneumoniae), Enterococcus faecalis (E. faecalis), Streptococcus agalactiae (S. agalactiae) and Staphylococcus hoemalyticus (S. hoemalyticus) respectively 2.70%. Real-time PCR targeted and detected Chlamydia trachomatis (C. trachomatis) at 7.89%, Ureaplasma urealyticum (U. urealyticum) at 21.05%, Ureaplasma parvum (U. parvum) at 18.42%, Mycoplasma hominis (M. hominis) at 15.79%, Mycoplasma genitalium (M. genitalium) at 10.53% and Trichomonas vaginalis (T. vaginalis) at 2.63%. Neisseria gonorrhoeae (N. gonorrhoeae) was targeted by the real-time PCR assay and was not detected (0%) in the tested semen samples. Our study highlights critical limitations of culture performance (low sensitivity), particularly in Burkina Faso, which has a total inability to detect microorganisms (fragile and demanding microorganisms) detected by PCR-based assays. There is therefore an urgent need to at least optimize culture, procedures and algorithms for detection of microorganisms associated with male infertility in clinical laboratories of Burkina Faso. The most effective solution is the routine implementation of molecular diagnostic methods.展开更多
[Objectives]To explore the effects of high soil temperature stress on microorganisms utilizing different carbon sources in the rhizosphere of pepper seedlings.[Methods]Using seedlings of the main pepper cultivar‘Reyi...[Objectives]To explore the effects of high soil temperature stress on microorganisms utilizing different carbon sources in the rhizosphere of pepper seedlings.[Methods]Using seedlings of the main pepper cultivar‘Reyin 1’as experimental materials,five soil temperature gradients(25,30,35,40,and 45℃)were established.After a 96 d cultivation,soil nutrient content and soil microbial functional diversity were measured to elucidate the impact of high soil temperature on the soil microenvironment.[Results]As soil temperature increased,the contents of total nitrogen,alkaline hydrolyzable nitrogen,available phosphorus,and rapidly available potassium generally showed a decreasing trend.However,under the 45℃ treatment,the contents of total nitrogen,available phosphorus,and rapidly available potassium were the highest among all treatments,although the alkaline hydrolyzable nitrogen content was significantly lower compared to the other treatments.BIOLOG analysis revealed that with increasing soil temperature,the average soil microbial absorbance value and the Shannon diversity index decreased significantly.In contrast,the Shannon evenness index and the Simpson dominance index showed no significant differences across the different temperature treatments.This indicates that as soil temperature rises,the carbon source utilization capacity of the soil microbial community decreases,leading to reduced overall carbon metabolic activity and microbial functional diversity,while the dominant microbial populations remained unchanged during this process.Principal component analysis further confirmed effective separation among the different temperature treatments,suggesting that high soil stress significantly altered the structure of the soil microbial community.[Conclusions]In practical production,appropriate measures should be taken to decrease soil temperature to create a favorable rhizosphere microenvironment and thereby promote crop growth.展开更多
[Objectives]To systematically investigate the microbial community composition of rhizosphere soil and endophytes associated with Pogostemon cablin,and to explore the relationships between endophytes and rhizosphere mi...[Objectives]To systematically investigate the microbial community composition of rhizosphere soil and endophytes associated with Pogostemon cablin,and to explore the relationships between endophytes and rhizosphere microorganisms as well as their potential applications.[Methods]Microbial isolates were obtained from rhizosphere soil,root tissues,and stem tissues using the serial dilution and spread plate method.These isolates were identified through morphological characterization,physiological and biochemical assays,and molecular biological techniques.[Results]A total of 18 microbial strains were isolated,including 7 bacterial and 11 fungal strains.Among the bacterial isolates,Pseudomonas spp.and Bacillus spp.were predominant,while the fungal isolates were mainly represented by Aspergillus spp.Certain bacterial strains,notably Pseudomonas spp.,exhibited potential abilities for indole-3-acetic acid(IAA)production,nitrogen fixation,and antagonistic activity against pathogenic microorganisms,suggesting their potential utility as biocontrol agents and promoters of plant growth.[Conclusions]This study establishes a foundational understanding of the microbial community characteristics in the rhizosphere and tissues of P.cablin,as well as their roles in plant growth and development.展开更多
Recently,returning straw to the fields has been proved as a direct and effective method to tackle soil nutrient loss and agricultural pollution.Meanwhile,the slow decomposition of straw may harm the growth of the next...Recently,returning straw to the fields has been proved as a direct and effective method to tackle soil nutrient loss and agricultural pollution.Meanwhile,the slow decomposition of straw may harm the growth of the next crop.This study aimed to determine the effects of rumen microorganisms(RMs)on straw decomposition,bacterial microbial community structure,soil properties,and soil enzyme activity.The results showed that RMs significantly enhanced the degradation rate of straw in the soil,reaching 39.52%,which was 41.37%higher than that of the control on the 30th day after straw return.After 30 d,straw degradation showed a significant slower trend in both the control and the experimental groups.According to the soil physicochemical parameters,the application of rumen fluid expedited soil matter transformation and nutrient buildup,and increased the urease,sucrase,and cellulase activity by 10%‒20%.The qualitative analysis of straw showed that the hydroxyl functional group structure of cellulose in straw was greatly damaged after the application of rumen fluid.The analysis of soil microbial community structure revealed that the addition of rumen fluid led to the proliferation of Actinobacteria with strong cellulose degradation ability,which was the main reason for the accelerated straw decomposition.Our study highlights that returning rice straw to the fields with rumen fluid inoculation can be used as an effective measure to enhance the biological value of recycled rice straw,proposing a viable solution to the problem of sluggish straw decomposition.展开更多
Oyster shell soil conditioner had significant influence on soil and rhizospheric microorganisms in their biomass,respiratory intensity and nutritional requirement. It could stimulate growth of soil and rhizospheric mi...Oyster shell soil conditioner had significant influence on soil and rhizospheric microorganisms in their biomass,respiratory intensity and nutritional requirement. It could stimulate growth of soil and rhizospheric microorganisms, especially nitrogen-fixers, and intensify soil respiration in proportion to the dose and fertilizing time of the conditioner, leading to the increase in the number of nitrogen fixing bacteria and the decrease in the number of bacteria with special nutrition demands.展开更多
Due to its strong and effective insecticidal properties, transgenic Bt＋CpTI cotton has witnessed an expanding planting area in recent years, and the impact of its cultivation on soil ecosystem becomes an important pa...Due to its strong and effective insecticidal properties, transgenic Bt＋CpTI cotton has witnessed an expanding planting area in recent years, and the impact of its cultivation on soil ecosystem becomes an important part of environmental risk assessment. Using transgenic Bt＋CpTI cotton sGK321 and its parental homologous conventional cotton Shiyuan 321 as the study objects, a comparative analysis was conducted on the changes in enzyme activities （urease, alkaline phosphatase, and catalase） of the rhizosphere soil and changes in the number of culturable microor-ganisms （bacteria, fungi, and actinomycetes） at different growth stages （seedling stage, budding stage, flower and bol stage, and bol opening stage） of sGK321 and Shiyuan 321 under the condition of 13 years field plantings. The results showed that, the populations of bacteria, fungi, and actinomycete and the soil enzyme activi-ties of urease, alkaline phosphatase and catalase had a similar variation trend along with the cotton growing process for transgenic cotton and conventional cotton. Some occasional and inconsistent effects on soil enzyme activities and soil fungi composi-tion in the rhizosphere soil of transgenic Bt＋CpTI cotton were found at the seedling stage, budding stage, flower and bol stage as compared with that of conventional cotton. The amount of bacteria and actinomycetes were not significantly different during a certain stage; however, the activities of urease, catalase, alkaline phos-phatase, also with the number of fungi were significantly different, e.g. the urease activities at seedling stage, the alkaline phosphatase at seedling and budding stages, and the soil culturable fungi at flower and bol stage were less than that of conven-tional cotton, while the soil alkaline phosphatase activities at flower and bol stage were higher. Cluster analysis showed that soil enzyme activities and microbial popu-lation changed mainly along the growth processes, suffering little from the planting of transgenic Bt＋CpTI cotton.展开更多
The method to analyze both eukaryotic and prokaryotic microorganisms without preliminary microbial information of sample seemed to be useful not only for research and investigation of microorganisms but also for indus...The method to analyze both eukaryotic and prokaryotic microorganisms without preliminary microbial information of sample seemed to be useful not only for research and investigation of microorganisms but also for industry using microorganisms. In the present manuscript, preparation of a new DNA primers, new reference database for 18S rDNA for our newly developed method [1]- [3], and analyses of eukaryotic and prokaryotic microorganisms in fermentation products were presented. In komekouji, Aspergillus spp., was enumerated to be 46.5 × 106 MPN g<sup>-1</sup>, and Penicillium spp., was enumerated to be 1.5 × 106 MPN g<sup>-1</sup>. In dry yeast, Saccharomyces group, were enumerated to be 8600 × 106 MPN g<sup>-1</sup>. In komekouji-miso, no eukaryotic microorganism was detected, while the other Bacillus spp., was numerically dominant (21.5 × 106 MPN g<sup>-1</sup>) as prokaryotic microorganisms, followed by B. subtilis group (4.65 × 106 MPN g<sup>-1</sup>), and the other Firmicutes (3.7 × 106 MPN g<sup>-1</sup>). The komekouji-miso included lower number of Actinobacteria (0.15 × 106 MPN g<sup>-1</sup>), Burkhokderia sp. (1.5 × 106 MPN g<sup>-1</sup>), and the other α,β,γ-proteobacteria (0.12 × 106 MPN g<sup>-1</sup>). In sake-kasu, both prokaryote and eukaryote were not detected by the method. Present results indicated that using both universal primers for eukaryotic and prokaryotic microorganisms, each groups of prokaryotic and eukaryotic microorganisms were enumerated without any preliminary information nor setting up standard curve, which were required for real time PCR.展开更多
[Objective]The paper was to provide reference for further study and development of gayal（Bos frontalis）.[Method]According to the research status at home and abroad,the biological characteristics and rumen microorgan...[Objective]The paper was to provide reference for further study and development of gayal（Bos frontalis）.[Method]According to the research status at home and abroad,the biological characteristics and rumen microorganisms of gayal in Yunnan Province was studied.[Result]Gayal in Yunnan had typical body form and very good meat production performance,its muscle fiber diameter was significantly less than other kinds of cattle;the water holding ratio,muscle tenderness and muscle succulency were significantly higher than others;its amount,shape and structure of chromosome were different from yellow cattle（Bos taurus）and wild cattle（Bos gaurus）,and the amounts of those chromosomes（2n）were 58,60 and 56,respectively.It could create hybrid with yellow cattle;the gayal＇s special diet was bamboo,its in vitro dry matter digestibility（IVDMD）on various crude forage was significantly higher than yellow cattle in Yunnan;the viable bacteria and cellulolytic bacteria in rumen were 4.51×109 and 1.63×109 CFU/ml,which was significantly higher than yellow cattle in Yunnan,its dominant bacteria in rumen mainly was cellulolytic bacteria.[Conclusion]Gayal not only had high academic value,but also had a great development value.展开更多
Biodegradation of polycyclic aromatic hydrocarbons （PAHs） is very difficult in saline-alkaline soil due to the inhibition of microbial growth under saline-alkaline stress. The microorganisms that can most effectivel...Biodegradation of polycyclic aromatic hydrocarbons （PAHs） is very difficult in saline-alkaline soil due to the inhibition of microbial growth under saline-alkaline stress. The microorganisms that can most effectively degrade PAHs were screened by introducing microorganisms immobilized on farm byproducts and assessing the validity of the immobilizing technique for PAHs degradation in pyrene-contaminated saline-alkaline soil. Among the microorganisms examined, it was found that Mycobacterium sp. B2 is the best, and can degrade 82.2% and 83.2% of pyrene for free and immobilized cells after 30 days of incubation. The immobilization technique could increase the degradation of pyrene significantly, especially for fungi. The degradation of pyrene by the immobilized microorganisms Mucor sp. F2, fungal consortium MF and co-cultures of MB＋MF was increased by 161.7% （P 〈 0.05）, 60.1% （P 〈 0.05） and 59.6% （P 〈 0.05） after 30 days, respectively, when compared with free F2, MF and MB＋ME Scanning electron micrographs of the immobilized microstructure proved the positive effects of the immobilized microbial technique on pyrene remediation in saline- alkaline soil, as the interspace of the carder material structure was relatively large, providing enough space for cell growth. Co-cultures of different bacterial and fungal species showed different abilities to degrade PAHs. The present study suggests that Mycobacterium sp. B2 can be employed for in situ bioremediation of PAHs in saline-alkaline soil, and immobilization of fungi on farm byproducts and nutrients as carriers will enhance fungus PAil-degradation ability in saline-alkaline soil.展开更多
The effects of complex microorganisms in composting process of the municipal solid waste (MSW) and sludge were examined through inspecting biomass, temperature, oxygen consumption, organic mater, and C/N (the ratio of...The effects of complex microorganisms in composting process of the municipal solid waste (MSW) and sludge were examined through inspecting biomass, temperature, oxygen consumption, organic mater, and C/N (the ratio of carbon and nitrogen). The experimental results shows: complex microorganisms are effective to compose organic matter and speedup composting change into humus.展开更多
Bioaerosol emissions from wastewater and wastewater treatment processes are a significant subgroup of atmospheric aerosols. Most previous work has focused on the evaluation of their biological risks. In this study, ho...Bioaerosol emissions from wastewater and wastewater treatment processes are a significant subgroup of atmospheric aerosols. Most previous work has focused on the evaluation of their biological risks. In this study, however, the adsorption method was applied to reduce airborne microorganisms generated from a pilot scale wastewater treatment facility with oxidation ditch. Results showed adsorption on granule activated carbon （GAC） was an efficient method for the purification of airborne microorganisms. The GAC itself had a maximum adsorption capacity of 2217 CFU/g for airborne bacteria and 225 CFU/g for fungi with a flow rate of 1.50 m^3/hr. Over 85% of airborne bacteria and fungi emitted from the oxidation ditch were adsorbed within 80 hr of continuous operation mode. Most of them had a particle size of 0.65-4.7 μm. Those airborne microorganisms with small particle size were apt to be adsorbed. The SEM/EDAX, BET and Boehm＇s titration methods were applied to analyse the physicochemical characteristics of the GAC. Relationships between GAC surface characteristics and its adsorption performance demonstrated that porous structure, large surface area, and hydrophobicity rendered GAC an effective absorber of airborne microorganisms. Two regenerate methods, ultraviolet irradiation and high pressure vapor, were compared for the regeneration of used activated carbon. High pressure vapor was an effective technique as it totally destroyed the microorganisms adhered to the activated carbon. Microscopic observation was also carried out to investigate original and used adsorbents.展开更多
Proliferation of filamentous microorganisms frequently leads to operational failure for activate sludge systems. In this study, it was found that filamentous microorganisms could grow in compact granular structure wit...Proliferation of filamentous microorganisms frequently leads to operational failure for activate sludge systems. In this study, it was found that filamentous microorganisms could grow in compact granular structure with 5% sodium chloride in the substrate. In the early period of experiment, coccoid and rode-like bacteria predominated in the yellowish-brown granules, and later the white and the black granules were developed by filamentous microorganisms. The filamentous granules exhibited low porosity and fast settling velocity, and were more compact even than bacteria granules. It was hypothesized that the elevated pH in the later period might be a possible reason for the compact growth of filamentous granules. However, the bacteria granules showed the high bioactivity in terms of specific oxygen utilizing rate, and comprised of a wider diversity of compounds based on the thermogravimetric evaluation. The findings in this study demonstrated that filamentous microbes could form compact granular structure, which may encourage the utilization of filamentous microorganisms rather than the inhibition of their growth, as the latter is frequently used for sludge bulking control.展开更多
Molar-tooth carbonate refers to a sort of rock that has ptygmatical folded structure comparable to the ivory. This kind of carbonate exists in a special time range (from Middle to Neoproterozoic). Its origin and the p...Molar-tooth carbonate refers to a sort of rock that has ptygmatical folded structure comparable to the ivory. This kind of carbonate exists in a special time range (from Middle to Neoproterozoic). Its origin and the possibility to use it in stratigraphic correlation of the paleocontinent is the key task of the IGCP447, a project on Proterozoic molar tooth carbonates and the evolution of the earth (2001-2005). The importance lies in that the molar-tooth structure is the key to solving problems related to Precambrian biological and global geochemical events. The molar-tooth structure is associated with microorganisms. Development and recession of such carbonates have relations with the evolution process of early lives and abrupt changes in sea carbonate geochemistry. In recent years, based on researches on petrology, geochemistry and Sr isotope of molar-tooth carbonate in the Jilin-Liaoning and Xuzhou-Huaiyang area, the authors hold that it can be used as a marker for stratigraphic sequence and sedimentary fades analyses.展开更多
In view of the fact that siderophores from microorganisms in different environments have received much attention in recent years because of their potential applications and diverse physiological functions, this review...In view of the fact that siderophores from microorganisms in different environments have received much attention in recent years because of their potential applications and diverse physiological functions, this review deals with side rophore producing marine microorganisms and the detection, chemical structure and potential applications of siderophores.展开更多
Until recently,potassium(K)has not received considerable attention because of the general belief that soils contain ample amounts of this element.In addition,low rates of K fertilizer application in agriculture have l...Until recently,potassium(K)has not received considerable attention because of the general belief that soils contain ample amounts of this element.In addition,low rates of K fertilizer application in agriculture have led to rapid depletion of K in the rhizosphere soil in many underdeveloped countries.This results in various negative impacts,including preventing optimum utilization of applied nitrogen and phosphorus fertilizers.To compensate for these losses,massive use of K fertilizers in agriculture has been suggested.Potassium fertilizers are manufactured from rock minerals,particularly sylvite(KCl)and carnallite(KCl·MgCl2·6H2O).Unfortunately,to date,there is no cost-effective technology available for converting rock minerals into potassic fertilizers.Potassium-solubilizing microorganisms(KSMs)can release K from soil/minerals into plant-available forms,which could be a sustainable option.The possibility of using KSMs as efficient biofertilizers to improve crop production has been increasingly highlighted by researchers.In this review,the existing forms of K in soils and their availability and dynamic equilibrium are discussed.In addition,different K fertilizers and their advantages and disadvantages for crops are described.Furthermore,the microorganisms usually reported as K solubilizers,the research progress on KSMs,and future insights on the use of these KSMs in agriculture are reviewed.Screening and analyses of the published literature show that organic acid production is the common mechanism of K solubilization by bacteria and fungi.This review may serve as a proposal for the future research avenues identified here.展开更多
Microbial application is an efficient, economical, and ecofriendly method for remediating black-odorous rivers. In this study, the field treatment effect and microbial community changes were monitored during remediati...Microbial application is an efficient, economical, and ecofriendly method for remediating black-odorous rivers. In this study, the field treatment effect and microbial community changes were monitored during remediation by the acclimated complex microorganisms of a typical black-odorous stream. After the treatment, the total phosphorus and ammonia contents decreased by 74.0% and 76.3% and the concentrations of dissolved oxygen increased from 1.65 to 4.90 mg/L, indicating the effectiveness of the acclimated composite microorganisms. The proportion of Bacteroidetes decreased significantly by 48.1% and that of Firmicutes increased by 2.23% on average, and the microbial diversity index first increased and then tended to be uniform. Redundancy analysis demonstrated that the pH,dissolved oxygen, and oxidation-reduction potential together determined the composition of the microbial communities(p < 0.05). These findings showed that the acclimated composite microorganisms can effectively remediate the black odor.展开更多
Objective To study the possibility of removing nitrogen, phosphorus, and organic pollutants using seeding type immobilized microorganisms. Methods Lakes P and M in Wuhan were chosen as the objects to study the removal...Objective To study the possibility of removing nitrogen, phosphorus, and organic pollutants using seeding type immobilized microorganisms. Methods Lakes P and M in Wuhan were chosen as the objects to study the removal of nitrogen, phosphorus, and organic pollutants with the seeding type immobilized microorganisms. Correlations between the quantity of heterotrophic bacteria and the total nitrogen （TN）, total phosphorus （TP）, and total organic carbon （TOC） in the two lakes were studied. The dominant bacteria were detected, inoculated to the sludge and acclimated by increasing nitrogen, phosphorus and decreasing carbon source in an intermittent, time-controlled and fixed-quantity way. The bacteria were then used to prepare the seeding type immobilized microorganisms, selecting diatomite as the adsorbent cartier. The ability and influence factors of removing nitrogen, phosphorus, and organic pollutant from water samples by the seeding type immobilized microorganisms were studied. Results The coefficients of the heterotrophic bacterial quantity correlated with TOC, TP, and TN were 0.9143, 0.8229, 0.7954 in Lake P and 0.9168, 0.7187, 0.6022 in Lake M. Ten strains of dominant heterotrophic bacteria belonging to Pseudomonas, Coccus, Aeromonas, Bacillus, and Enterobateriaceae, separately, were isolated. The appropriate conditions for the seeding type immobilized microorgansims in purifying the water sample were exposure time=24 h, pH=7.0-8.0, and quantity of the immobilized microorganisms=0.75-1g/50 mL. The removal rates of TOC, TP, and TN under the above conditions were 80.2%, 81.6%, and 86.8%, respectively. Conclusion The amount of heterotrophic bacteria in the two lakes was correlated with TOC, TP, and TN. These bacteria could be acclimatized and prepared for the immobilized microorganisms which could effectively remove nitrogen, phosphorus, and mixed organic pollutants in the water sample.展开更多
Black soybeans [Glycine max（L.） Merrill] were fermented with various GRAS（generally recognized as safe） microorganisms,including Aspergillus sp.,Bacillus sp.and yeast（Issatchenkia orientalis） at 30°C for 3 ...Black soybeans [Glycine max（L.） Merrill] were fermented with various GRAS（generally recognized as safe） microorganisms,including Aspergillus sp.,Bacillus sp.and yeast（Issatchenkia orientalis） at 30°C for 3 d.The antioxidant contents,including total phenolics and total flavonoids,and the antioxidant activities of 1,1-diphenyl-2-picrylhydrazine（DPPH）,ferric reducing antioxidant power（FRAP） and HO.scavenging were analyzed in preparations of fermented black soybeans.Fermented cultures proved to yield significant levels of antioxidants compared with non-fermented cultures（P 〈 0.05）.Fermented black soybean preparations possessed antioxidant activities could be attributed to the total phenolics and flavonoids present.展开更多
A mixed culture of moderately thermophilic microorganisms was enriched from acid mine drainages(AMDs)samples collected from several sulphide mines in China,and the bioleaching of chalcopyrite was conducted both in sha...A mixed culture of moderately thermophilic microorganisms was enriched from acid mine drainages(AMDs)samples collected from several sulphide mines in China,and the bioleaching of chalcopyrite was conducted both in shake flask and bioreactor.The results show that in the shake flask,the mixture can tolerate 50 g/L chalcopyrite after being acclimated to gradually increased concentrations of chalcopyrite.The copper extraction increases obviously in bioleaching of chalcopyrite with moderately thermophilic microorganisms supplemented with 0.4 g/L yeast extract at 180 r/min,74% copper can be extracted in the pulp of 50 g/L chalcopyrite after 20 d.Compared with copper extractions of mesophilic culture,unacclimated culture and acclimated culture without addition of yeast extract,that of accliniated culture with addition of yeast extract is increased by 53%,44% and 16%,respectively.In a completely stirred tank reactor,the mass fraction of copper and total iron extraction reach up to 81% and 56%,respectively.The results also indicate that it is necessary to add a large amount of acid to the pulp to extract copper from chalcopyrite effectively.展开更多
Bioremediation plays an increasingly important role in the remediation of chromium-contaminated soil because it is an environmentally friendly technology. To investigate the Cr(Ⅵ)reduction process by indigenous micro...Bioremediation plays an increasingly important role in the remediation of chromium-contaminated soil because it is an environmentally friendly technology. To investigate the Cr(Ⅵ)reduction process by indigenous microorganisms in soil, a batch of incubation experiments were carried out in a bioreactor under aerobic conditions. The results showed that in the presence of indigenous microorganisms, the Cr(Ⅵ) concentration in the chromium-contaminated soil decreased from 1521.9 to 199.2 mg/kg within 66 h with culture medium addition, while a slight decrease in the Cr(Ⅵ) concentration was found in the sterilized soil,implying that the indigenous microorganisms contributed to the Cr(Ⅵ) reduction. In the microbial remediation process, Cr(Ⅵ)microbial reduction occurred after the reduction of NO3-, Mn4+ and Fe3+ and,before SO42- reduction. The reduction process of Cr(Ⅵ) can be divided into two phases, characterized by the exponential equation model of microbial reduction and the linear equation model of the combined effect of the major ions. It can be concluded that indigenous Cr(Ⅵ)-reducing bacteria have a potential application for in-situ remediation of Cr(Ⅵ)-contaminated soil.展开更多
文摘In Burkina Faso, as in other African countries, infertility has become a social burden for the population and a public health problem. Male infertility accounts for 30% to 40% of all infertility cases. The diagnosis of male infertility or hypofertility is often made by a simple laboratory analysis of sperm to explore sperm parameters. In most African countries, such as Burkina Faso, microbiological analysis in the context of sperm analysis is still not developed, and is carried out solely based on microscopy and traditional culture, which does not allow the growth of fragile and demanding bacteria. Our study investigated the microorganisms of sperm that may be involved in male infertility, using conventional bacteriology techniques and real-time PCR. However, it did not intend to perform a multivariate statistical association analysis to estimate the association of microorganisms with abnormal semen parameters. This prospective cross-sectional pilot study was carried out on patients who visited the bacteriology laboratory of Centre MURAZ, a research Institute in Burkina Faso, for male infertility diagnosis between 2 August and 31 August 2021. Bacteria were isolated and identified using standard bacteriology techniques. In parallel, common pathogenic microorganisms known to be associated with male infertility were targeted and detected in the sperm using a multiplex real-time PCR assay. A total of 38 sperm samples were analyzed by bacteriological culture and bacteria isolated were Staphylococcus aureus (S. aureus) 5.55%, Klebsiella pneumoniae (K. pneumoniae), Enterococcus faecalis (E. faecalis), Streptococcus agalactiae (S. agalactiae) and Staphylococcus hoemalyticus (S. hoemalyticus) respectively 2.70%. Real-time PCR targeted and detected Chlamydia trachomatis (C. trachomatis) at 7.89%, Ureaplasma urealyticum (U. urealyticum) at 21.05%, Ureaplasma parvum (U. parvum) at 18.42%, Mycoplasma hominis (M. hominis) at 15.79%, Mycoplasma genitalium (M. genitalium) at 10.53% and Trichomonas vaginalis (T. vaginalis) at 2.63%. Neisseria gonorrhoeae (N. gonorrhoeae) was targeted by the real-time PCR assay and was not detected (0%) in the tested semen samples. Our study highlights critical limitations of culture performance (low sensitivity), particularly in Burkina Faso, which has a total inability to detect microorganisms (fragile and demanding microorganisms) detected by PCR-based assays. There is therefore an urgent need to at least optimize culture, procedures and algorithms for detection of microorganisms associated with male infertility in clinical laboratories of Burkina Faso. The most effective solution is the routine implementation of molecular diagnostic methods.
基金Supported by Natural Science Foundation of Hainan Province(320MS108)Scientific and Technological Innovation Team of the National Center for Tropical Agricultural Science,Chinese Academy of Tropical Agricultural Sciences(CATASCXTD202303)Key Laboratory of Genetic Resources Utilization of Spice and Beverage Crops,Ministry of Agriculture and Rural Affairs,Hainan Provincial Key Laboratory of Genetic Improvement and Quality Regulation for Tropical Spice and Beverage Crops,or Hainan Provincial Engineering Research Center for Tropical Spice and Beverage Crops(2019xys007).
文摘[Objectives]To explore the effects of high soil temperature stress on microorganisms utilizing different carbon sources in the rhizosphere of pepper seedlings.[Methods]Using seedlings of the main pepper cultivar‘Reyin 1’as experimental materials,five soil temperature gradients(25,30,35,40,and 45℃)were established.After a 96 d cultivation,soil nutrient content and soil microbial functional diversity were measured to elucidate the impact of high soil temperature on the soil microenvironment.[Results]As soil temperature increased,the contents of total nitrogen,alkaline hydrolyzable nitrogen,available phosphorus,and rapidly available potassium generally showed a decreasing trend.However,under the 45℃ treatment,the contents of total nitrogen,available phosphorus,and rapidly available potassium were the highest among all treatments,although the alkaline hydrolyzable nitrogen content was significantly lower compared to the other treatments.BIOLOG analysis revealed that with increasing soil temperature,the average soil microbial absorbance value and the Shannon diversity index decreased significantly.In contrast,the Shannon evenness index and the Simpson dominance index showed no significant differences across the different temperature treatments.This indicates that as soil temperature rises,the carbon source utilization capacity of the soil microbial community decreases,leading to reduced overall carbon metabolic activity and microbial functional diversity,while the dominant microbial populations remained unchanged during this process.Principal component analysis further confirmed effective separation among the different temperature treatments,suggesting that high soil stress significantly altered the structure of the soil microbial community.[Conclusions]In practical production,appropriate measures should be taken to decrease soil temperature to create a favorable rhizosphere microenvironment and thereby promote crop growth.
基金Supported by Rural Science and Technology Commissioner Project of Guangdong Province(KTP20240806).
文摘[Objectives]To systematically investigate the microbial community composition of rhizosphere soil and endophytes associated with Pogostemon cablin,and to explore the relationships between endophytes and rhizosphere microorganisms as well as their potential applications.[Methods]Microbial isolates were obtained from rhizosphere soil,root tissues,and stem tissues using the serial dilution and spread plate method.These isolates were identified through morphological characterization,physiological and biochemical assays,and molecular biological techniques.[Results]A total of 18 microbial strains were isolated,including 7 bacterial and 11 fungal strains.Among the bacterial isolates,Pseudomonas spp.and Bacillus spp.were predominant,while the fungal isolates were mainly represented by Aspergillus spp.Certain bacterial strains,notably Pseudomonas spp.,exhibited potential abilities for indole-3-acetic acid(IAA)production,nitrogen fixation,and antagonistic activity against pathogenic microorganisms,suggesting their potential utility as biocontrol agents and promoters of plant growth.[Conclusions]This study establishes a foundational understanding of the microbial community characteristics in the rhizosphere and tissues of P.cablin,as well as their roles in plant growth and development.
基金National Natural Science Foundation of China(Nos.52160002,21707057,and 31860595)Natural Science Foundation of Jiangxi Province(No.20192BAB213018).
文摘Recently,returning straw to the fields has been proved as a direct and effective method to tackle soil nutrient loss and agricultural pollution.Meanwhile,the slow decomposition of straw may harm the growth of the next crop.This study aimed to determine the effects of rumen microorganisms(RMs)on straw decomposition,bacterial microbial community structure,soil properties,and soil enzyme activity.The results showed that RMs significantly enhanced the degradation rate of straw in the soil,reaching 39.52%,which was 41.37%higher than that of the control on the 30th day after straw return.After 30 d,straw degradation showed a significant slower trend in both the control and the experimental groups.According to the soil physicochemical parameters,the application of rumen fluid expedited soil matter transformation and nutrient buildup,and increased the urease,sucrase,and cellulase activity by 10%‒20%.The qualitative analysis of straw showed that the hydroxyl functional group structure of cellulose in straw was greatly damaged after the application of rumen fluid.The analysis of soil microbial community structure revealed that the addition of rumen fluid led to the proliferation of Actinobacteria with strong cellulose degradation ability,which was the main reason for the accelerated straw decomposition.Our study highlights that returning rice straw to the fields with rumen fluid inoculation can be used as an effective measure to enhance the biological value of recycled rice straw,proposing a viable solution to the problem of sluggish straw decomposition.
基金support from the 863 National High-Technology Program of China(819-07-10).
文摘Oyster shell soil conditioner had significant influence on soil and rhizospheric microorganisms in their biomass,respiratory intensity and nutritional requirement. It could stimulate growth of soil and rhizospheric microorganisms, especially nitrogen-fixers, and intensify soil respiration in proportion to the dose and fertilizing time of the conditioner, leading to the increase in the number of nitrogen fixing bacteria and the decrease in the number of bacteria with special nutrition demands.
文摘Due to its strong and effective insecticidal properties, transgenic Bt＋CpTI cotton has witnessed an expanding planting area in recent years, and the impact of its cultivation on soil ecosystem becomes an important part of environmental risk assessment. Using transgenic Bt＋CpTI cotton sGK321 and its parental homologous conventional cotton Shiyuan 321 as the study objects, a comparative analysis was conducted on the changes in enzyme activities （urease, alkaline phosphatase, and catalase） of the rhizosphere soil and changes in the number of culturable microor-ganisms （bacteria, fungi, and actinomycetes） at different growth stages （seedling stage, budding stage, flower and bol stage, and bol opening stage） of sGK321 and Shiyuan 321 under the condition of 13 years field plantings. The results showed that, the populations of bacteria, fungi, and actinomycete and the soil enzyme activi-ties of urease, alkaline phosphatase and catalase had a similar variation trend along with the cotton growing process for transgenic cotton and conventional cotton. Some occasional and inconsistent effects on soil enzyme activities and soil fungi composi-tion in the rhizosphere soil of transgenic Bt＋CpTI cotton were found at the seedling stage, budding stage, flower and bol stage as compared with that of conventional cotton. The amount of bacteria and actinomycetes were not significantly different during a certain stage; however, the activities of urease, catalase, alkaline phos-phatase, also with the number of fungi were significantly different, e.g. the urease activities at seedling stage, the alkaline phosphatase at seedling and budding stages, and the soil culturable fungi at flower and bol stage were less than that of conven-tional cotton, while the soil alkaline phosphatase activities at flower and bol stage were higher. Cluster analysis showed that soil enzyme activities and microbial popu-lation changed mainly along the growth processes, suffering little from the planting of transgenic Bt＋CpTI cotton.
文摘The method to analyze both eukaryotic and prokaryotic microorganisms without preliminary microbial information of sample seemed to be useful not only for research and investigation of microorganisms but also for industry using microorganisms. In the present manuscript, preparation of a new DNA primers, new reference database for 18S rDNA for our newly developed method [1]- [3], and analyses of eukaryotic and prokaryotic microorganisms in fermentation products were presented. In komekouji, Aspergillus spp., was enumerated to be 46.5 × 106 MPN g<sup>-1</sup>, and Penicillium spp., was enumerated to be 1.5 × 106 MPN g<sup>-1</sup>. In dry yeast, Saccharomyces group, were enumerated to be 8600 × 106 MPN g<sup>-1</sup>. In komekouji-miso, no eukaryotic microorganism was detected, while the other Bacillus spp., was numerically dominant (21.5 × 106 MPN g<sup>-1</sup>) as prokaryotic microorganisms, followed by B. subtilis group (4.65 × 106 MPN g<sup>-1</sup>), and the other Firmicutes (3.7 × 106 MPN g<sup>-1</sup>). The komekouji-miso included lower number of Actinobacteria (0.15 × 106 MPN g<sup>-1</sup>), Burkhokderia sp. (1.5 × 106 MPN g<sup>-1</sup>), and the other α,β,γ-proteobacteria (0.12 × 106 MPN g<sup>-1</sup>). In sake-kasu, both prokaryote and eukaryote were not detected by the method. Present results indicated that using both universal primers for eukaryotic and prokaryotic microorganisms, each groups of prokaryotic and eukaryotic microorganisms were enumerated without any preliminary information nor setting up standard curve, which were required for real time PCR.
基金Supported by National Natural Science Foundation of China(30960256,31060314)Project of Yunnan Education Department(V09Y0202)~~
文摘[Objective]The paper was to provide reference for further study and development of gayal（Bos frontalis）.[Method]According to the research status at home and abroad,the biological characteristics and rumen microorganisms of gayal in Yunnan Province was studied.[Result]Gayal in Yunnan had typical body form and very good meat production performance,its muscle fiber diameter was significantly less than other kinds of cattle;the water holding ratio,muscle tenderness and muscle succulency were significantly higher than others;its amount,shape and structure of chromosome were different from yellow cattle（Bos taurus）and wild cattle（Bos gaurus）,and the amounts of those chromosomes（2n）were 58,60 and 56,respectively.It could create hybrid with yellow cattle;the gayal＇s special diet was bamboo,its in vitro dry matter digestibility（IVDMD）on various crude forage was significantly higher than yellow cattle in Yunnan;the viable bacteria and cellulolytic bacteria in rumen were 4.51×109 and 1.63×109 CFU/ml,which was significantly higher than yellow cattle in Yunnan,its dominant bacteria in rumen mainly was cellulolytic bacteria.[Conclusion]Gayal not only had high academic value,but also had a great development value.
基金supported by the National Science Foundation of China(No.41101295)the Natural Science Fund Project of Liaoning Province(No.201102226)+1 种基金the Open Foundation of Key Laboratory of Industrial Ecology and Environmental Engineering(MOE)(No.KLIEEE-09-04)the Key Program of National Science Foundation of China(No.40930739)
文摘Biodegradation of polycyclic aromatic hydrocarbons （PAHs） is very difficult in saline-alkaline soil due to the inhibition of microbial growth under saline-alkaline stress. The microorganisms that can most effectively degrade PAHs were screened by introducing microorganisms immobilized on farm byproducts and assessing the validity of the immobilizing technique for PAHs degradation in pyrene-contaminated saline-alkaline soil. Among the microorganisms examined, it was found that Mycobacterium sp. B2 is the best, and can degrade 82.2% and 83.2% of pyrene for free and immobilized cells after 30 days of incubation. The immobilization technique could increase the degradation of pyrene significantly, especially for fungi. The degradation of pyrene by the immobilized microorganisms Mucor sp. F2, fungal consortium MF and co-cultures of MB＋MF was increased by 161.7% （P 〈 0.05）, 60.1% （P 〈 0.05） and 59.6% （P 〈 0.05） after 30 days, respectively, when compared with free F2, MF and MB＋ME Scanning electron micrographs of the immobilized microstructure proved the positive effects of the immobilized microbial technique on pyrene remediation in saline- alkaline soil, as the interspace of the carder material structure was relatively large, providing enough space for cell growth. Co-cultures of different bacterial and fungal species showed different abilities to degrade PAHs. The present study suggests that Mycobacterium sp. B2 can be employed for in situ bioremediation of PAHs in saline-alkaline soil, and immobilization of fungi on farm byproducts and nutrients as carriers will enhance fungus PAil-degradation ability in saline-alkaline soil.
文摘The effects of complex microorganisms in composting process of the municipal solid waste (MSW) and sludge were examined through inspecting biomass, temperature, oxygen consumption, organic mater, and C/N (the ratio of carbon and nitrogen). The experimental results shows: complex microorganisms are effective to compose organic matter and speedup composting change into humus.
基金supported by the National Natural Science Foundation of China (No.50921064, 50978249)
文摘Bioaerosol emissions from wastewater and wastewater treatment processes are a significant subgroup of atmospheric aerosols. Most previous work has focused on the evaluation of their biological risks. In this study, however, the adsorption method was applied to reduce airborne microorganisms generated from a pilot scale wastewater treatment facility with oxidation ditch. Results showed adsorption on granule activated carbon （GAC） was an efficient method for the purification of airborne microorganisms. The GAC itself had a maximum adsorption capacity of 2217 CFU/g for airborne bacteria and 225 CFU/g for fungi with a flow rate of 1.50 m^3/hr. Over 85% of airborne bacteria and fungi emitted from the oxidation ditch were adsorbed within 80 hr of continuous operation mode. Most of them had a particle size of 0.65-4.7 μm. Those airborne microorganisms with small particle size were apt to be adsorbed. The SEM/EDAX, BET and Boehm＇s titration methods were applied to analyse the physicochemical characteristics of the GAC. Relationships between GAC surface characteristics and its adsorption performance demonstrated that porous structure, large surface area, and hydrophobicity rendered GAC an effective absorber of airborne microorganisms. Two regenerate methods, ultraviolet irradiation and high pressure vapor, were compared for the regeneration of used activated carbon. High pressure vapor was an effective technique as it totally destroyed the microorganisms adhered to the activated carbon. Microscopic observation was also carried out to investigate original and used adsorbents.
基金supported by the National Natural Science Foundation of China (No.50708089)the Program for Changjiang Scholars and Innovative Research Team in University of MOE of China (PCSIRT) (No.IRT0853)+1 种基金the Natural Science Foundation of Shaanxi Province (No.2009JQ7002)the Research Plant for Key Laboratoryof Universities of Shaanxi Province (No.09JS027)
文摘Proliferation of filamentous microorganisms frequently leads to operational failure for activate sludge systems. In this study, it was found that filamentous microorganisms could grow in compact granular structure with 5% sodium chloride in the substrate. In the early period of experiment, coccoid and rode-like bacteria predominated in the yellowish-brown granules, and later the white and the black granules were developed by filamentous microorganisms. The filamentous granules exhibited low porosity and fast settling velocity, and were more compact even than bacteria granules. It was hypothesized that the elevated pH in the later period might be a possible reason for the compact growth of filamentous granules. However, the bacteria granules showed the high bioactivity in terms of specific oxygen utilizing rate, and comprised of a wider diversity of compounds based on the thermogravimetric evaluation. The findings in this study demonstrated that filamentous microbes could form compact granular structure, which may encourage the utilization of filamentous microorganisms rather than the inhibition of their growth, as the latter is frequently used for sludge bulking control.
基金This study was sponsored by the Key Program of International Scientific and Technological Cooperation of Ministry of Science and Technology of China(2001 CB 711002)the National Natural Science Foundation of China(No.4017043)the International Geological Correlation Program(IGCP)project 447.
文摘Molar-tooth carbonate refers to a sort of rock that has ptygmatical folded structure comparable to the ivory. This kind of carbonate exists in a special time range (from Middle to Neoproterozoic). Its origin and the possibility to use it in stratigraphic correlation of the paleocontinent is the key task of the IGCP447, a project on Proterozoic molar tooth carbonates and the evolution of the earth (2001-2005). The importance lies in that the molar-tooth structure is the key to solving problems related to Precambrian biological and global geochemical events. The molar-tooth structure is associated with microorganisms. Development and recession of such carbonates have relations with the evolution process of early lives and abrupt changes in sea carbonate geochemistry. In recent years, based on researches on petrology, geochemistry and Sr isotope of molar-tooth carbonate in the Jilin-Liaoning and Xuzhou-Huaiyang area, the authors hold that it can be used as a marker for stratigraphic sequence and sedimentary fades analyses.
文摘In view of the fact that siderophores from microorganisms in different environments have received much attention in recent years because of their potential applications and diverse physiological functions, this review deals with side rophore producing marine microorganisms and the detection, chemical structure and potential applications of siderophores.
文摘Until recently,potassium(K)has not received considerable attention because of the general belief that soils contain ample amounts of this element.In addition,low rates of K fertilizer application in agriculture have led to rapid depletion of K in the rhizosphere soil in many underdeveloped countries.This results in various negative impacts,including preventing optimum utilization of applied nitrogen and phosphorus fertilizers.To compensate for these losses,massive use of K fertilizers in agriculture has been suggested.Potassium fertilizers are manufactured from rock minerals,particularly sylvite(KCl)and carnallite(KCl·MgCl2·6H2O).Unfortunately,to date,there is no cost-effective technology available for converting rock minerals into potassic fertilizers.Potassium-solubilizing microorganisms(KSMs)can release K from soil/minerals into plant-available forms,which could be a sustainable option.The possibility of using KSMs as efficient biofertilizers to improve crop production has been increasingly highlighted by researchers.In this review,the existing forms of K in soils and their availability and dynamic equilibrium are discussed.In addition,different K fertilizers and their advantages and disadvantages for crops are described.Furthermore,the microorganisms usually reported as K solubilizers,the research progress on KSMs,and future insights on the use of these KSMs in agriculture are reviewed.Screening and analyses of the published literature show that organic acid production is the common mechanism of K solubilization by bacteria and fungi.This review may serve as a proposal for the future research avenues identified here.
基金supported by the Science and Technology program of Yantai (No. 2017ZH095)。
文摘Microbial application is an efficient, economical, and ecofriendly method for remediating black-odorous rivers. In this study, the field treatment effect and microbial community changes were monitored during remediation by the acclimated complex microorganisms of a typical black-odorous stream. After the treatment, the total phosphorus and ammonia contents decreased by 74.0% and 76.3% and the concentrations of dissolved oxygen increased from 1.65 to 4.90 mg/L, indicating the effectiveness of the acclimated composite microorganisms. The proportion of Bacteroidetes decreased significantly by 48.1% and that of Firmicutes increased by 2.23% on average, and the microbial diversity index first increased and then tended to be uniform. Redundancy analysis demonstrated that the pH,dissolved oxygen, and oxidation-reduction potential together determined the composition of the microbial communities(p < 0.05). These findings showed that the acclimated composite microorganisms can effectively remediate the black odor.
基金This work was supported by the National Natural Science Foundation of China (No. 30400346)
文摘Objective To study the possibility of removing nitrogen, phosphorus, and organic pollutants using seeding type immobilized microorganisms. Methods Lakes P and M in Wuhan were chosen as the objects to study the removal of nitrogen, phosphorus, and organic pollutants with the seeding type immobilized microorganisms. Correlations between the quantity of heterotrophic bacteria and the total nitrogen （TN）, total phosphorus （TP）, and total organic carbon （TOC） in the two lakes were studied. The dominant bacteria were detected, inoculated to the sludge and acclimated by increasing nitrogen, phosphorus and decreasing carbon source in an intermittent, time-controlled and fixed-quantity way. The bacteria were then used to prepare the seeding type immobilized microorganisms, selecting diatomite as the adsorbent cartier. The ability and influence factors of removing nitrogen, phosphorus, and organic pollutant from water samples by the seeding type immobilized microorganisms were studied. Results The coefficients of the heterotrophic bacterial quantity correlated with TOC, TP, and TN were 0.9143, 0.8229, 0.7954 in Lake P and 0.9168, 0.7187, 0.6022 in Lake M. Ten strains of dominant heterotrophic bacteria belonging to Pseudomonas, Coccus, Aeromonas, Bacillus, and Enterobateriaceae, separately, were isolated. The appropriate conditions for the seeding type immobilized microorgansims in purifying the water sample were exposure time=24 h, pH=7.0-8.0, and quantity of the immobilized microorganisms=0.75-1g/50 mL. The removal rates of TOC, TP, and TN under the above conditions were 80.2%, 81.6%, and 86.8%, respectively. Conclusion The amount of heterotrophic bacteria in the two lakes was correlated with TOC, TP, and TN. These bacteria could be acclimatized and prepared for the immobilized microorganisms which could effectively remove nitrogen, phosphorus, and mixed organic pollutants in the water sample.
基金supproted by a grant from the Korea Institute of Planning and Evaluation for Technology of Food,Agriculture,Forestry and Fishes (i PET)
文摘Black soybeans [Glycine max（L.） Merrill] were fermented with various GRAS（generally recognized as safe） microorganisms,including Aspergillus sp.,Bacillus sp.and yeast（Issatchenkia orientalis） at 30°C for 3 d.The antioxidant contents,including total phenolics and total flavonoids,and the antioxidant activities of 1,1-diphenyl-2-picrylhydrazine（DPPH）,ferric reducing antioxidant power（FRAP） and HO.scavenging were analyzed in preparations of fermented black soybeans.Fermented cultures proved to yield significant levels of antioxidants compared with non-fermented cultures（P 〈 0.05）.Fermented black soybean preparations possessed antioxidant activities could be attributed to the total phenolics and flavonoids present.
基金Project(50621063, 40646029) supported by the National Natural Science Foundation of ChinaProject (2004CB619204) supported by the National Basic Research Program
文摘A mixed culture of moderately thermophilic microorganisms was enriched from acid mine drainages(AMDs)samples collected from several sulphide mines in China,and the bioleaching of chalcopyrite was conducted both in shake flask and bioreactor.The results show that in the shake flask,the mixture can tolerate 50 g/L chalcopyrite after being acclimated to gradually increased concentrations of chalcopyrite.The copper extraction increases obviously in bioleaching of chalcopyrite with moderately thermophilic microorganisms supplemented with 0.4 g/L yeast extract at 180 r/min,74% copper can be extracted in the pulp of 50 g/L chalcopyrite after 20 d.Compared with copper extractions of mesophilic culture,unacclimated culture and acclimated culture without addition of yeast extract,that of accliniated culture with addition of yeast extract is increased by 53%,44% and 16%,respectively.In a completely stirred tank reactor,the mass fraction of copper and total iron extraction reach up to 81% and 56%,respectively.The results also indicate that it is necessary to add a large amount of acid to the pulp to extract copper from chalcopyrite effectively.
基金Project(2018SK2044)supported by the Innovation Program of Science&Technology of Hunan Province,ChinaProject(51304250)supported by the National Natural Science Foundation of China
文摘Bioremediation plays an increasingly important role in the remediation of chromium-contaminated soil because it is an environmentally friendly technology. To investigate the Cr(Ⅵ)reduction process by indigenous microorganisms in soil, a batch of incubation experiments were carried out in a bioreactor under aerobic conditions. The results showed that in the presence of indigenous microorganisms, the Cr(Ⅵ) concentration in the chromium-contaminated soil decreased from 1521.9 to 199.2 mg/kg within 66 h with culture medium addition, while a slight decrease in the Cr(Ⅵ) concentration was found in the sterilized soil,implying that the indigenous microorganisms contributed to the Cr(Ⅵ) reduction. In the microbial remediation process, Cr(Ⅵ)microbial reduction occurred after the reduction of NO3-, Mn4+ and Fe3+ and,before SO42- reduction. The reduction process of Cr(Ⅵ) can be divided into two phases, characterized by the exponential equation model of microbial reduction and the linear equation model of the combined effect of the major ions. It can be concluded that indigenous Cr(Ⅵ)-reducing bacteria have a potential application for in-situ remediation of Cr(Ⅵ)-contaminated soil.
