12%difenoconazole+fluxapyroxad SC(commercial name:Jiangong)was first released by BASF in China in 2016.It has been registered to control many diseases,including pear scab,apple Alternaria leaf spot,tomato early blight...12%difenoconazole+fluxapyroxad SC(commercial name:Jiangong)was first released by BASF in China in 2016.It has been registered to control many diseases,including pear scab,apple Alternaria leaf spot,tomato early blight,cucumber powdery mildew,etc.This study evaluated the bioactivity of Jiangong against Alternaria alternata and explored variations of phyllosphere microorganisms in both asymptomatic and tobacco brown spot leaves at different persistence periods(0,5,10,and 15 days post-fungicide application)using high-throughput sequencing technology.The results indicated that Jiangong effectively inhibited mycelial growth(average EC_(50) value of 0.51μg/mL),conidia germination(average EC_(50) value of 3.47μg/mL),and the carbon metabolism of A.alternata.Both asymptomatic and symptomatic leaves presented complex microbial communities.Higher fungal diversity was noted in asymptomatic leaves,while higher bacterial diversity was found in symptomatic leaves.After application,the diversity and abundance of microbial community structures in both types of leaves changed over time.Fungal microbiome communities showed greater sensitivity than bacterial groups,with the microbiome communities of asymptomatic leaves being more affected than those of symptomatic leaves.Fungal community diversity decreased for both symptomatic and asymptomatic leaves after 5 days of application,while the diversity of fungal community in symptomatic leaves showed an upward trend after 10 days of application.Meanwhile,bacterial community diversity increased in both symptomatic and asymptomatic leaves after 5 days of application but then declined in asymptomatic leaves after 15 days.The abundance of the dominant function group of phyllosphere bacteria(metabolism,genetic information processing,environmental information processing)was not affected by the application of Jiangong.However,the abundance of the dominant function group of phyllosphere fungi(animal pathogen-endophyte-wood saprotroph,endophyte-plant pathogen,plant pathogen-undefined saprotroph)was significantly affected by the application of Jiangong,and high variation was found in symptomatic leaves than that of asymptomatic leaves.The application of Jiangong-induced alterations in the community structure of the tobacco phyllosphere microbiome provides a basis for future tobacco brown spot control strategies based on phyllospheric microecology.展开更多
Fermented plant-based foods and beverages constitute foods of high nutritional and functional value with appreciated health beneficial effects.They represent a natural and sustainable alternative to counteract the lar...Fermented plant-based foods and beverages constitute foods of high nutritional and functional value with appreciated health beneficial effects.They represent a natural and sustainable alternative to counteract the large wastage of vegetables and fruits due to their short shelf life.Usually,the use of controlled fermentation process using autochthonous microorganisms adapted to their vegetable matrix is preferred instead of traditionally spontaneous fermentation to designing fermented vegetable foods with the desirable sensory,technological,nutritional and functional properties.This review summarizes the autochthonous microorganisms selected as starters for the successful fermentation of vegetables and fruits.The main beneficial properties of autochthonous starters and fermented vegetable products with a focus on human health are revised.展开更多
Mixed mesophilic and extreme thermophilic bioleaching were evaluated to remove copper from the molybdenite concentrate.Bioleaching tests were carried out in shake flasks and in a 50-L bioreactor.The shake flask tests ...Mixed mesophilic and extreme thermophilic bioleaching were evaluated to remove copper from the molybdenite concentrate.Bioleaching tests were carried out in shake flasks and in a 50-L bioreactor.The shake flask tests were performed with different inoculum size,solids density,pH.and temperature in order to identify optimum conditions.The highest amount of copper elimination,75%was obtained with extreme thermophilic microorganisms(at 12%inoculation,10%solids,65℃and a pH of 1.5).The highest copper elimination by mesophilic microorganisms was 55%(at 12%inoculation,5%solids,30℃at pH 2).The optimum conditions in shake flask tests were applied to 7 days batch tests in a50-L bioreactor.Extreme thermophilic experiment gave the best copper elimination of 60%(at 12%inoculation,10%solids,65℃and pH 1.5).Mesophilic test removed 50%of the copper(at 12%inoculation,10%solids,35℃at pH 2).展开更多
On the basis of the analysis of the process of treating low concentrations of sulfur dioxide （SO2） gas in a fixed bed reactor, a kinetic model is proposed for this process after taking into consideration the effects...On the basis of the analysis of the process of treating low concentrations of sulfur dioxide （SO2） gas in a fixed bed reactor, a kinetic model is proposed for this process after taking into consideration the effects of internal diffusion, cell concentration, and production yield of microorganisms but ignoring the effect of external diffusion. The results obtained from the model simulation show that this model can indicate the influence of the process factors, Cin, η μmax, Cx, A, h, Kin, and Q, on the removal of SO2 and that the prediction of the results by this model is also satisfactory. This kinetic model can also provide some very important indications regarding the preparation of immobilized microorganisms, selection and domestication of proper species of microorganisms, as well as the design of bioreactors.展开更多
To have a preliminary insight into biosafety of genetically transformed hybrid triploid poplars （Populus tomentosa × P bolleana）× P. tomentosa with the cowpea trypsin inhibitor （CpTD gene, two layers of r...To have a preliminary insight into biosafety of genetically transformed hybrid triploid poplars （Populus tomentosa × P bolleana）× P. tomentosa with the cowpea trypsin inhibitor （CpTD gene, two layers of rhizospheric soil （from 0 to 20cm deep and from 20 to 40cm deep, respectively） were collected for microorganism culture, counting assay and PCR analysis to assess the potential impact of transgenic poplars on non-target microorganism population and transgene dispersal. When the same soil layer of suspension stock solution was diluted at both 1：1000 and 1：10000 rates, there were no significant differences in bacterium colony numbers between the inoculation plates of both transgenic and non-transgenic poplars. The uniform results were revealed for both soil layer suspension solutions of identical poplars at both dilution rates except for non-transgenic poplars at 1：10000 dilution rates from the same type of soil. No significant variation in morphology of both Gram-positive and Gram-negative bacteria was observed under the microscope. The potential transgene dispersal from root exudates or fallen leaves to non-target microbes was repudiated by PCR analysis, in which no CpTI gene specific DNA band was amplified for 15 sites of transgenic rhizospheric soil samples. It can be concluded that transgenic poplar with the CpTI gene has no severe impact on rhizospheric microorganisms and is tentatively safe to surrounding soil micro-ecosystem.展开更多
Soil samples were collected from the surface soil of three kinds of plantations mixed plantation of Dahurian larch and Manchurian ash, pure ash plantation and pure larch plantation, at Maoershan Forest experiment cent...Soil samples were collected from the surface soil of three kinds of plantations mixed plantation of Dahurian larch and Manchurian ash, pure ash plantation and pure larch plantation, at Maoershan Forest experiment center in Heilongjiang Province. The result of measuring and analysis showed that the number of the bacteria was the most and their effective scope and active strength were the most remarkable comparing with various kinds of soil microorganisms. Actinomyces were the second most and the fungi were the least in number Numbers of the soil microorganisms in mixed plantation had a more number than that in the pure ash plantation. The number and species of microorganisms were different among different soil layers. For the same kind of soil, the number and species of the microorganisms in the surface layer were the most, and declined wth the increase of the soil depth. The seasonal change of the number of the soil microorganisms in pure or mixed pIantations was also remarkable. The number of the microorganisms increases obviously with the increase of the atmospheric temperature. The total number of microorganisms in Jan. was 30.0%-40.2% of the number in Sep. Both the vertical distribution and seasonal change being concerned, the number of the soil microorganisms in mixed plantation was on a higher level than that in pure plantation.展开更多
Atmospheric nitrogen(N)deposition is predicted to increase,especially in the subtropics.However,the responses of soil microorganisms to long-term N addition at the molecular level in N-rich subtropical forests have no...Atmospheric nitrogen(N)deposition is predicted to increase,especially in the subtropics.However,the responses of soil microorganisms to long-term N addition at the molecular level in N-rich subtropical forests have not been clarified.A long-term nutrient addition experiment was conducted in a subtropical evergreen old-growth forest in China.The four treatments were:control,low N(50 kg N ha^(-1)a^(-1)),high N(100 kg N ha^(-1)a^(-1)),and combined N and phosphorus(P)(100 kg N ha^(-1)a^(-1)+50 kg P ha^(-1)a^(-1)).Metagenomic sequencing characterized diversity and composition of soil microbial communities and used to construct bacterial/fungal co-occurrence networks.Nutrient-treated soils were more acidic and had higher levels of dissolved organic carbon than controls.There were no significant differences in microbial diversity and community composition across treatments.The addition of nutrients increased the abundance of copiotrophic bacteria and potentially beneficial microorganisms(e.g.,Gemmatimonadetes,Chaetomium,and Aureobasidium).Low N addition increased microbiome network connectivity.Three rare fungi were identified as module hubs under nutrient addition,indicating that low abundance fungi were more sensitive to increased nutrients.The results indicate that the overall composition of microbial communities was stable but not static to long-term N addition.Our findings provide new insights that can aid predictions of the response of soil microbial communities to long-term N addition.展开更多
The swimming performance of rod-shaped microswimmers in a channel was numerically investigated using the two-dimensional lattice Boltzmann method(LBM).We considered variable-length squirmer rods,assembled from circula...The swimming performance of rod-shaped microswimmers in a channel was numerically investigated using the two-dimensional lattice Boltzmann method(LBM).We considered variable-length squirmer rods,assembled from circular squirmer models with self-propulsion mechanisms,and analyzed the effects of the Reynolds number(Re),aspect ratio(ε),squirmer-type factor(β)and blockage ratio(κ)on swimming efficiency(η)and power expenditure(P).The results show no significant difference in power expenditure between pushers(microswimmers propelled from the tail)and pullers(microswimmers propelled from the head)at the low Reynolds numbers adopted in this study.However,the swimming efficiency of pushers surpasses that of pullers.Moreover,as the degree of channel blockage increases(i.e.,κincreases),the squirmer rod consumes more energy while swimming,and its swimming efficiency also increases,which is clearly reflected whenε≤3.Notably,squirmer rods with a larger aspect ratioεand aβvalue approaching 0 can achieve high swimming efficiency with lower power expenditure.The advantages of self-propelled microswimmers are manifested whenε>4 andβ=±1,where the squirmer rod consumes less energy than a passive rod driven by an external field.These findings underscore the potential for designing more efficient microswimmers by carefully considering the interactions between the microswimmer geometry,propulsion mechanism and fluid dynamic environment.展开更多
The application of microorganisms as probiotics is limited due to lack of safety evaluation.Here,a novel multi-stress-tolerant yeast Meyerozyma guilliermondii GXDK6 with aroma-producing properties was identified from ...The application of microorganisms as probiotics is limited due to lack of safety evaluation.Here,a novel multi-stress-tolerant yeast Meyerozyma guilliermondii GXDK6 with aroma-producing properties was identified from marine mangrove microorganisms.Its safety and probiotic properties were assessed in accordance with phenotype and whole-genome sequencing analysis.Results showed that the genes and phenotypic expression of related virulence,antibiotic resistance and retroelement were rarely found.Hyphal morphogenesis genes(SIT4,HOG1,SPA2,ERK1,ICL1,CST20,HSP104,TPS1,and RHO1)and phospholipase secretion gene(VPS4)were annotated.True hyphae and phospholipase were absent.Only one retroelement(Tad1-65_BG)was found.Major biogenic amines(BAs)encoding genes were absent,except for spermidine synthase(JA9_002594),spermine synthase(JA9_004690),and tyrosine decarboxylase(inx).The production of single BAs and total BAs was far below the food-defined thresholds.GXDK6 had no resistance to common antifungal drugs.Virulence enzymes,such as gelatinase,DNase,hemolytic,lecithinase,and thrombin were absent.Acute toxicity test with mice demonstrated that GXDK6 is safe.GXDK6 has a good reproduction ability in the simulation gastrointestinal tract.GXDK6 also has a strong antioxidant ability,β-glucosidase,and inulinase activity.To sum up,GXDK6 is considered as a safe probiotic for human consumption and food fermentation.展开更多
Widespread forest fires pose significant challenges to the diverse communities of soil-dwelling organisms and the multiple ecosystem functions they support.However,whether the biodiversity and interactions of various ...Widespread forest fires pose significant challenges to the diverse communities of soil-dwelling organisms and the multiple ecosystem functions they support.However,whether the biodiversity and interactions of various taxonomic groups respond to fire consistently in terms of direction and extent,and their relative role in regulating post-fire soil functioning,remains largely unexplored.In this study,we investigated whether the diversity and co-occurrence networks of soil organisms across various trophic levels(including bacteria,fungi,protists,and invertebrates)in subtropical forests exhibit consistent responses to fire.Furthermore,we investigated their contribution to regulating soil multifunctionality,which is measured by a range of soil extracellular enzyme activities,available nutrients and reduced potential fungal plant pathogens.Our findings revealed that fire led to a decline in the richness of fungi,protists,and invertebrates,without significantly impacting bacterial richness.Fire also simplified the microbial co-occurrence networks while complexifying the invertebrate networks.Interestingly,soil multifunctionality tended to decrease with the richness of lower-trophic communities(i.e.,bacteria),whereas it increased with that of high-trophic communities(i.e.,protists and invertebrates).Moreover,fire indirectly influenced soil multifunctionality by altering biodiversity and network complexity,particularly pronounced in high-trophic communities.Overall,our results underscored the divergent vulnerability of biodiversity and networks to fires across taxa groups,highlighting the crucial role of biodiversity and interactions of higher trophic taxa groups in shaping the recovery and functionality of fire-affected soils.展开更多
We evaluated the effects of the number of years of restoration of vegetation on soil microbial community structure and biomass in degraded ecosystems.We investigated the microbial community structure by analyzing thei...We evaluated the effects of the number of years of restoration of vegetation on soil microbial community structure and biomass in degraded ecosystems.We investigated the microbial community structure by analyzing their phospholipid fatty acids then examined microbial biomass carbon and nitrogen by chloroform fumigation extraction of restoration soils over several years.The data were compared with those of highly degraded lands and native vegetation sites.The results show that the duration of vegetation on the sites substantially increased microbial biomass and shifted the microbial community structure even after only 4 years.However,microbial communities and biomass did not recover to the status of native vegetation even after 35 years of vegetation cover.A redundancy analysis and Pearson correlation analysis indicated that soil organic carbon,total nitrogen,available potassium,soil water content,silt content and soil hardness explained 98.4%of total variability in the microbial community composition.Soil organic carbon,total nitrogen,available potassium and soil water content were positively correlated with microbial community structure and biomass,whereas,soil hardness and silt content were negatively related to microbial community structure and biomass.This study provides new insights into microbial community structure and biomass that influence organic carbon,nitrogen,phosphorus and potassium accumulation,and clay content in soils at different stages of restoration.展开更多
Background:Inputs of above-and belowground litter into forest soils are changing at an unprecedented rate due to continuing human disturbances and climate change.Microorganisms drive the soil carbon(C)cycle,but the ro...Background:Inputs of above-and belowground litter into forest soils are changing at an unprecedented rate due to continuing human disturbances and climate change.Microorganisms drive the soil carbon(C)cycle,but the roles of above-and belowground litter in regulating the soil microbial community have not been evaluated at a global scale.Methods:Here,we conducted a meta-analysis based on 68 aboveground litter removal and root exclusion studies across forest ecosystems to quantify the roles of above-and belowground litter on soil microbial community and compare their relative importance.Results:Aboveground litter removal significantly declined soil microbial biomass by 4.9%but root exclusion inhibited it stronger,up to 11.7%.Moreover,the aboveground litter removal significantly raised fungi by 10.1%without altering bacteria,leading to a 46.7%increase in the fungi-to-bacteria(F/B)ratio.Differently,root exclusion significantly decreased the fungi by 26.2%but increased the bacteria by 5.7%,causing a 13.3%decrease in the F/B ratio.Specifically,root exclusion significantly inhibited arbuscular mycorrhizal fungi,ectomycorrhizal fungi,and actinomycetes by 22.9%,43.8%,and 7.9%,respectively.The negative effects of aboveground litter removal on microbial biomass increased with mean annual temperature and precipitation,whereas that of root exclusion on microbial biomass did not change with climatic factors but amplified with treatment duration.More importantly,greater effects of root exclusion on microbial biomass than aboveground litter removal were consistent across diverse forest biomes(expect boreal forests)and durations.Conclusions:These data provide a global evidence that root litter inputs exert a larger control on microbial biomass than aboveground litter inputs in forest ecosystems.Our study also highlights that changes in above-and belowground litter inputs could alter soil C stability differently by shifting the microbial community structure in the opposite direction.These findings are useful for predicting microbe-mediated C processes in response to changes in forest management or climate.展开更多
The effect of forests clear felling and associated burning on the population of soil nitrogen transforming bacteria and actinomycetes are reported at three pair sites of Chittagong University campus, Bangla- desh in m...The effect of forests clear felling and associated burning on the population of soil nitrogen transforming bacteria and actinomycetes are reported at three pair sites of Chittagong University campus, Bangla- desh in monsoon tropical climate. Clear felled area or burnt site and 15-21 year mixed plantation of native and exotic species, situated side by side on low hill having Typic Dystrochrepts soil was represented at each pair site. At all the three pair sites, clear felled area or burnt site showed very significantly （p~_0.001） lower population of actinomycetes, Rhizobium, Nitrosomonas, Nitrobacter and ammonifying as well as deni- trifying bacteria compared to their adjacent mixed plantation. From en- vironmental consideration, this finding has implication in managing natural ecosystem.展开更多
In this study,physicochemical,cluster,and high-throughput sequencing analyses were used to investigate the joint effects of salt and herbicide(glyphosate)stress factors on the microbial remediation of soil contaminate...In this study,physicochemical,cluster,and high-throughput sequencing analyses were used to investigate the joint effects of salt and herbicide(glyphosate)stress factors on the microbial remediation of soil contaminated by n-hexadecane and phenanthrene.Based on the soil’s physical and chemical properties,differences in microbial quantity and enzyme activities were analyzed among the samples,and how that influenced distribution of soil community structure was focused upon.After 120 days of indoor simulated remediation,the cumulative degradation rate of n-hexadecane decreased by 94.92%(blank control),96.96%(low concentration salt and glyphosate stress group),65.07%(high concentration salt and glyphosate stress group),while that of phenanthrene decreased by 87.33%(blank control),86.25%(low concentration salt and glyphosate stress group),58.45%(high concentration salt and glyphosate stress group).The combined stress of salt and herbicides was capable of lowering the reduction efficiency of organic matter,total nitrogen,and total phosphorus,and also restricting the growth of microorganisms and enzyme activities.Cluster analysis results indicated that the non-stress group was similar to the low-concentration compound stress group during different remedial period,whereas both of those differed starkly from the high-concentration compound stress group.High-throughput sequencing revealed that the dominant soil bacteria phyla shifted from Firmicutes to Actinobacteria within 120 days of remediation.展开更多
The microbial sulfur removal was investigated on high sulfur content (1.9%) coal concentrate from Tabas coal preparation plant. A mixed culture of ferrooxidans microorganisms was isolated from the tailing dam of the p...The microbial sulfur removal was investigated on high sulfur content (1.9%) coal concentrate from Tabas coal preparation plant. A mixed culture of ferrooxidans microorganisms was isolated from the tailing dam of the plant. Full factorial method was used to design laboratory test and to evaluate the effects of pH, particle size, iron sulfate concentration, pulp density, and bioleaching time on sulfur reduction. Statistical analyses of experimental data were considered and showed increases of pH and particle size had negative effects on sulfur reduction, whereas increases of pulp density and bioleaching time raised microbial desulfurization rate. According to results of designing, and regarding statistical factors, the optimum values for maximum sulfur reduction were obtained; pH (1.5), particle size (-180 μm), iron sulfate concentration (2.7 mmol/L), pulp density (10%) and bioleaching time (14 d), which leaded to 51.5% reduction from the total sulfur of sample.展开更多
Use of legume trees can improve soil quality in degraded pastures. The aim of this study was to charac- terize C and N mineralization kinetics and estimate the potentially mineralizable C and N in soil under Mimosa ca...Use of legume trees can improve soil quality in degraded pastures. The aim of this study was to charac- terize C and N mineralization kinetics and estimate the potentially mineralizable C and N in soil under Mimosa caesalpiniifolia Benth. and Acacia auriculiformis A. Cunn. ex Benth. secondary forest and pasture in red-yellow latosols in southeast Brazil. We conducted a laboratory aerobic incubation experiment using a completely ran- domized design of four replicates and four types of plant cover using a modified version of the Stanford and Smith technique （1972） to study C and N mineralization potential. Potentially mineralizable N （No） ranged from 135 to 170 mg kg-1. The predominant form of mineral N for all types of plant cover was N-NO3-. M. caesalpiniifolia was the only species that had a positive influence on N min- eralization. Neither of the legumes influenced C mineral- ization in pasture or secondary forest. The model of N mineralization corresponded to a sigmoidal curve while C mineralization corresponded to an exponential curve, revealing that the N and C mineralization processes were distinct. N mineralized by M. caesalpiniifolia （216 kg ofN ha-1） was adequate to meet the N requirement for a livestock-forest system.展开更多
Metabolic associated fatty liver disease(MAFLD)has become a prevalent chronic liver disease worldwide because of lifestyle and dietary changes.Gut microbiota and its metabolites have been shown to play a critical role...Metabolic associated fatty liver disease(MAFLD)has become a prevalent chronic liver disease worldwide because of lifestyle and dietary changes.Gut microbiota and its metabolites have been shown to play a critical role in the pathogenesis of MAFLD.Understanding of the function of gut microbiota and its metabolites in MAFLD may help to elucidate pathological mechanisms,identify diagnostic markers,and develop drugs or probiotics for the treatment of MAFLD.Here we review the pathogenesis of MAFLD by gut microbiota and its metabolites and discuss the feasibility of treating MAFLD from the perspective of gut microbes.展开更多
Isabel grape(IG)products have high contents of phenolic compounds and fiber recognized for their positive impacts on microorganisms associated with health benefits to host.This study evaluated the effects of goat yogu...Isabel grape(IG)products have high contents of phenolic compounds and fiber recognized for their positive impacts on microorganisms associated with health benefits to host.This study evaluated the effects of goat yogurts formulated with ingredients from IG integral valorization on the growth and metabolism of different probiotic strains,as well as on the population of selected bacterial groups and metabolic activity of human colonic microbiota in vitro.Goat yogurts with IG ingredients(IGI)stimulated the growth of tested Lactobacillus and Bifidobacterium probiotic strains during a 48-h cultivation,as well as decreased the pH values and enhanced the organic acid production.Goat yogurts with IGI increased the population of Lactobacillus spp.and Bifidobacterium spp.during a 24-h in vitro colonic fermentation.A stable Firmicutes:Bacteroidetes ratio close to 1 was found in media with goat yogurt formulations during the colonic fermentation,being similar to the effect caused by fructooligosaccharides.Goat yogurt formulations with IGI caused increased production of short-chain fatty acids and sugar consumption during colonic fermentation.Goat yogurts with IGI should be a valuable strategy for development of novel added-value foods with beneficial effects on gut microbiota and human health.展开更多
Microorganism DNA of rhizosphere soil from Pinus koraiensis and Pinus sylvestriformis were extracted by proteinase K based on SDS method, CTAB method, PVP （polyvinylpolypyrrolidone） method, and freezing and thawing ...Microorganism DNA of rhizosphere soil from Pinus koraiensis and Pinus sylvestriformis were extracted by proteinase K based on SDS method, CTAB method, PVP （polyvinylpolypyrrolidone） method, and freezing and thawing method and the crude DNA from rhizosphere soil were purified by dialysis method, silver beads absorption method, and squeezing DNA gel method. The results of different extracting and purifying methods were compared and evaluated. Results indicated that the best method of extraction for microorganism DNA in rhizosphere soil was proteinse K based on SDS method with high salt concentration of 1.0% （w/v） NaCl, which could effectively eliminate humic acids and other impurities. The dialysis method was suitable to purify DNA from rhizosphere soil because of effectively removing brown matters and humic acids and the purified products were suited to PCR amplification. Squeezing DNA gel method was also a good purification method with the advantage of inexpensive in cost and efficient in use.展开更多
Oil pollution in marine environment is becoming increasingly serious. Oil bioremediation by immobilization technology has been widely studied. However, the effect of bacteria immobilization was limited because of lack...Oil pollution in marine environment is becoming increasingly serious. Oil bioremediation by immobilization technology has been widely studied. However, the effect of bacteria immobilization was limited because of lack of nutrients. In this paper, the organic materials(corn straw, corn cob and corn leaf) were used as carriers. The diesel removal rate achieved by the immobilized bacteria was studied, and the effects of nutrients(e.g. nitrogen and phosphorus) released from organic carriers to the immobilized bacteria were analyzed. Test results indicated that a certain amount of nutrients was released from organic carriers. Additionally, the diesel removal rates achieved by different immobilized bacteria were all higher than those achieved by free bacteria. And, the diesel removal rates achieved by bacteria decreased in the following order: bacteria immobilized on corn straw(79%), bacteria immobilized on corn leaf(70%) and bacteria immobilized on corn cob(43%). These findings indicated two aspects, viz.: the carriers porous structure and the nutrients, which were favorable to biodegradation. Finally, the changes in nitrogen and phosphorus contents that were released from different carriers during biodegradation were studied. The results showed that the rate of diesel biodegradation was fast in the initial phase because of the sufficient nutrients released from carriers. Meanwhile, in the final phase, the rate of diesel biodegradation was relatively slow because of few nutrients released from carriers.展开更多
基金Supported by China National Tobacco Corporation[No.110202101048(LS-08)]Hundred’Level Innovative Talent Foundation of Guizhou Province(No.GCC[2022]028-1,GCC[2023]108)+2 种基金Guizhou Science Technology Foundation(No.ZK[2021]Key036)the National Natural Science Foundation of China(No.32160522)Guizhou Province Applied Technology Research and Development Funding Post-subsidy Project and Guizhou Tobacco Company(No.2020XM03,2020XM22,2024XM06).
文摘12%difenoconazole+fluxapyroxad SC(commercial name:Jiangong)was first released by BASF in China in 2016.It has been registered to control many diseases,including pear scab,apple Alternaria leaf spot,tomato early blight,cucumber powdery mildew,etc.This study evaluated the bioactivity of Jiangong against Alternaria alternata and explored variations of phyllosphere microorganisms in both asymptomatic and tobacco brown spot leaves at different persistence periods(0,5,10,and 15 days post-fungicide application)using high-throughput sequencing technology.The results indicated that Jiangong effectively inhibited mycelial growth(average EC_(50) value of 0.51μg/mL),conidia germination(average EC_(50) value of 3.47μg/mL),and the carbon metabolism of A.alternata.Both asymptomatic and symptomatic leaves presented complex microbial communities.Higher fungal diversity was noted in asymptomatic leaves,while higher bacterial diversity was found in symptomatic leaves.After application,the diversity and abundance of microbial community structures in both types of leaves changed over time.Fungal microbiome communities showed greater sensitivity than bacterial groups,with the microbiome communities of asymptomatic leaves being more affected than those of symptomatic leaves.Fungal community diversity decreased for both symptomatic and asymptomatic leaves after 5 days of application,while the diversity of fungal community in symptomatic leaves showed an upward trend after 10 days of application.Meanwhile,bacterial community diversity increased in both symptomatic and asymptomatic leaves after 5 days of application but then declined in asymptomatic leaves after 15 days.The abundance of the dominant function group of phyllosphere bacteria(metabolism,genetic information processing,environmental information processing)was not affected by the application of Jiangong.However,the abundance of the dominant function group of phyllosphere fungi(animal pathogen-endophyte-wood saprotroph,endophyte-plant pathogen,plant pathogen-undefined saprotroph)was significantly affected by the application of Jiangong,and high variation was found in symptomatic leaves than that of asymptomatic leaves.The application of Jiangong-induced alterations in the community structure of the tobacco phyllosphere microbiome provides a basis for future tobacco brown spot control strategies based on phyllospheric microecology.
基金The present review was supported by the grant PICT-2017-4436 from Agencia Nacional de Promocion Cientifica y Tecnologica.
文摘Fermented plant-based foods and beverages constitute foods of high nutritional and functional value with appreciated health beneficial effects.They represent a natural and sustainable alternative to counteract the large wastage of vegetables and fruits due to their short shelf life.Usually,the use of controlled fermentation process using autochthonous microorganisms adapted to their vegetable matrix is preferred instead of traditionally spontaneous fermentation to designing fermented vegetable foods with the desirable sensory,technological,nutritional and functional properties.This review summarizes the autochthonous microorganisms selected as starters for the successful fermentation of vegetables and fruits.The main beneficial properties of autochthonous starters and fermented vegetable products with a focus on human health are revised.
基金supported by the National Iranian Copper Industry Co.
文摘Mixed mesophilic and extreme thermophilic bioleaching were evaluated to remove copper from the molybdenite concentrate.Bioleaching tests were carried out in shake flasks and in a 50-L bioreactor.The shake flask tests were performed with different inoculum size,solids density,pH.and temperature in order to identify optimum conditions.The highest amount of copper elimination,75%was obtained with extreme thermophilic microorganisms(at 12%inoculation,10%solids,65℃and a pH of 1.5).The highest copper elimination by mesophilic microorganisms was 55%(at 12%inoculation,5%solids,30℃at pH 2).The optimum conditions in shake flask tests were applied to 7 days batch tests in a50-L bioreactor.Extreme thermophilic experiment gave the best copper elimination of 60%(at 12%inoculation,10%solids,65℃and pH 1.5).Mesophilic test removed 50%of the copper(at 12%inoculation,10%solids,35℃at pH 2).
基金This project was supported by the National Natural Science Foundation of China (2003E0027M)
文摘On the basis of the analysis of the process of treating low concentrations of sulfur dioxide （SO2） gas in a fixed bed reactor, a kinetic model is proposed for this process after taking into consideration the effects of internal diffusion, cell concentration, and production yield of microorganisms but ignoring the effect of external diffusion. The results obtained from the model simulation show that this model can indicate the influence of the process factors, Cin, η μmax, Cx, A, h, Kin, and Q, on the removal of SO2 and that the prediction of the results by this model is also satisfactory. This kinetic model can also provide some very important indications regarding the preparation of immobilized microorganisms, selection and domestication of proper species of microorganisms, as well as the design of bioreactors.
文摘To have a preliminary insight into biosafety of genetically transformed hybrid triploid poplars （Populus tomentosa × P bolleana）× P. tomentosa with the cowpea trypsin inhibitor （CpTD gene, two layers of rhizospheric soil （from 0 to 20cm deep and from 20 to 40cm deep, respectively） were collected for microorganism culture, counting assay and PCR analysis to assess the potential impact of transgenic poplars on non-target microorganism population and transgene dispersal. When the same soil layer of suspension stock solution was diluted at both 1：1000 and 1：10000 rates, there were no significant differences in bacterium colony numbers between the inoculation plates of both transgenic and non-transgenic poplars. The uniform results were revealed for both soil layer suspension solutions of identical poplars at both dilution rates except for non-transgenic poplars at 1：10000 dilution rates from the same type of soil. No significant variation in morphology of both Gram-positive and Gram-negative bacteria was observed under the microscope. The potential transgene dispersal from root exudates or fallen leaves to non-target microbes was repudiated by PCR analysis, in which no CpTI gene specific DNA band was amplified for 15 sites of transgenic rhizospheric soil samples. It can be concluded that transgenic poplar with the CpTI gene has no severe impact on rhizospheric microorganisms and is tentatively safe to surrounding soil micro-ecosystem.
文摘Soil samples were collected from the surface soil of three kinds of plantations mixed plantation of Dahurian larch and Manchurian ash, pure ash plantation and pure larch plantation, at Maoershan Forest experiment center in Heilongjiang Province. The result of measuring and analysis showed that the number of the bacteria was the most and their effective scope and active strength were the most remarkable comparing with various kinds of soil microorganisms. Actinomyces were the second most and the fungi were the least in number Numbers of the soil microorganisms in mixed plantation had a more number than that in the pure ash plantation. The number and species of microorganisms were different among different soil layers. For the same kind of soil, the number and species of the microorganisms in the surface layer were the most, and declined wth the increase of the soil depth. The seasonal change of the number of the soil microorganisms in pure or mixed pIantations was also remarkable. The number of the microorganisms increases obviously with the increase of the atmospheric temperature. The total number of microorganisms in Jan. was 30.0%-40.2% of the number in Sep. Both the vertical distribution and seasonal change being concerned, the number of the soil microorganisms in mixed plantation was on a higher level than that in pure plantation.
基金supported by the National Science Foundation of China(No.31770672 and 3137062)the National Basic Research Program of China(No.2010CB950602)。
文摘Atmospheric nitrogen(N)deposition is predicted to increase,especially in the subtropics.However,the responses of soil microorganisms to long-term N addition at the molecular level in N-rich subtropical forests have not been clarified.A long-term nutrient addition experiment was conducted in a subtropical evergreen old-growth forest in China.The four treatments were:control,low N(50 kg N ha^(-1)a^(-1)),high N(100 kg N ha^(-1)a^(-1)),and combined N and phosphorus(P)(100 kg N ha^(-1)a^(-1)+50 kg P ha^(-1)a^(-1)).Metagenomic sequencing characterized diversity and composition of soil microbial communities and used to construct bacterial/fungal co-occurrence networks.Nutrient-treated soils were more acidic and had higher levels of dissolved organic carbon than controls.There were no significant differences in microbial diversity and community composition across treatments.The addition of nutrients increased the abundance of copiotrophic bacteria and potentially beneficial microorganisms(e.g.,Gemmatimonadetes,Chaetomium,and Aureobasidium).Low N addition increased microbiome network connectivity.Three rare fungi were identified as module hubs under nutrient addition,indicating that low abundance fungi were more sensitive to increased nutrients.The results indicate that the overall composition of microbial communities was stable but not static to long-term N addition.Our findings provide new insights that can aid predictions of the response of soil microbial communities to long-term N addition.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12372251 and 12132015)the Fundamental Research Funds for the Provincial Universities of Zhejiang(Grant No.2023YW69)。
文摘The swimming performance of rod-shaped microswimmers in a channel was numerically investigated using the two-dimensional lattice Boltzmann method(LBM).We considered variable-length squirmer rods,assembled from circular squirmer models with self-propulsion mechanisms,and analyzed the effects of the Reynolds number(Re),aspect ratio(ε),squirmer-type factor(β)and blockage ratio(κ)on swimming efficiency(η)and power expenditure(P).The results show no significant difference in power expenditure between pushers(microswimmers propelled from the tail)and pullers(microswimmers propelled from the head)at the low Reynolds numbers adopted in this study.However,the swimming efficiency of pushers surpasses that of pullers.Moreover,as the degree of channel blockage increases(i.e.,κincreases),the squirmer rod consumes more energy while swimming,and its swimming efficiency also increases,which is clearly reflected whenε≤3.Notably,squirmer rods with a larger aspect ratioεand aβvalue approaching 0 can achieve high swimming efficiency with lower power expenditure.The advantages of self-propelled microswimmers are manifested whenε>4 andβ=±1,where the squirmer rod consumes less energy than a passive rod driven by an external field.These findings underscore the potential for designing more efficient microswimmers by carefully considering the interactions between the microswimmer geometry,propulsion mechanism and fluid dynamic environment.
基金This research was supported by the Funding Project of Chinese Central Government Guiding to the Guangxi Local Science and Technology Development(GUIKEZY21195021)the Natural Science Fund for Distinguished Young Scholars of Guangxi Zhuang Autonomous Region of China(2019GXNSFFA245011)+3 种基金the Funding Project of Chinese Central Government Guiding to the Nanning Local Science and Technology Development(20231012)the Funding Projects of Guangxi Key Research and Development Plan(GUIKE AB23075173)the Funding Project of Technological Development from Angel Yeast(Chongzuo)Co.,Ltd.(JS1006020230722019)the Innovation Project of Guangxi Graduate Education(YCBZ2021012).
文摘The application of microorganisms as probiotics is limited due to lack of safety evaluation.Here,a novel multi-stress-tolerant yeast Meyerozyma guilliermondii GXDK6 with aroma-producing properties was identified from marine mangrove microorganisms.Its safety and probiotic properties were assessed in accordance with phenotype and whole-genome sequencing analysis.Results showed that the genes and phenotypic expression of related virulence,antibiotic resistance and retroelement were rarely found.Hyphal morphogenesis genes(SIT4,HOG1,SPA2,ERK1,ICL1,CST20,HSP104,TPS1,and RHO1)and phospholipase secretion gene(VPS4)were annotated.True hyphae and phospholipase were absent.Only one retroelement(Tad1-65_BG)was found.Major biogenic amines(BAs)encoding genes were absent,except for spermidine synthase(JA9_002594),spermine synthase(JA9_004690),and tyrosine decarboxylase(inx).The production of single BAs and total BAs was far below the food-defined thresholds.GXDK6 had no resistance to common antifungal drugs.Virulence enzymes,such as gelatinase,DNase,hemolytic,lecithinase,and thrombin were absent.Acute toxicity test with mice demonstrated that GXDK6 is safe.GXDK6 has a good reproduction ability in the simulation gastrointestinal tract.GXDK6 also has a strong antioxidant ability,β-glucosidase,and inulinase activity.To sum up,GXDK6 is considered as a safe probiotic for human consumption and food fermentation.
基金financially supported by the National Natural Science Foundation of China(Nos.42377288,32201528)the Natural Science Foundation of Fujian Province(No.2021J05040).
文摘Widespread forest fires pose significant challenges to the diverse communities of soil-dwelling organisms and the multiple ecosystem functions they support.However,whether the biodiversity and interactions of various taxonomic groups respond to fire consistently in terms of direction and extent,and their relative role in regulating post-fire soil functioning,remains largely unexplored.In this study,we investigated whether the diversity and co-occurrence networks of soil organisms across various trophic levels(including bacteria,fungi,protists,and invertebrates)in subtropical forests exhibit consistent responses to fire.Furthermore,we investigated their contribution to regulating soil multifunctionality,which is measured by a range of soil extracellular enzyme activities,available nutrients and reduced potential fungal plant pathogens.Our findings revealed that fire led to a decline in the richness of fungi,protists,and invertebrates,without significantly impacting bacterial richness.Fire also simplified the microbial co-occurrence networks while complexifying the invertebrate networks.Interestingly,soil multifunctionality tended to decrease with the richness of lower-trophic communities(i.e.,bacteria),whereas it increased with that of high-trophic communities(i.e.,protists and invertebrates).Moreover,fire indirectly influenced soil multifunctionality by altering biodiversity and network complexity,particularly pronounced in high-trophic communities.Overall,our results underscored the divergent vulnerability of biodiversity and networks to fires across taxa groups,highlighting the crucial role of biodiversity and interactions of higher trophic taxa groups in shaping the recovery and functionality of fire-affected soils.
基金This work was supported by the National Key Research and Development Plan Projects of China(Grant No.2017YFC05054)the Graduate Student Science and Technology Innovation Project of the School of Geographical Science at Fujian Normal University(B2015112).
文摘We evaluated the effects of the number of years of restoration of vegetation on soil microbial community structure and biomass in degraded ecosystems.We investigated the microbial community structure by analyzing their phospholipid fatty acids then examined microbial biomass carbon and nitrogen by chloroform fumigation extraction of restoration soils over several years.The data were compared with those of highly degraded lands and native vegetation sites.The results show that the duration of vegetation on the sites substantially increased microbial biomass and shifted the microbial community structure even after only 4 years.However,microbial communities and biomass did not recover to the status of native vegetation even after 35 years of vegetation cover.A redundancy analysis and Pearson correlation analysis indicated that soil organic carbon,total nitrogen,available potassium,soil water content,silt content and soil hardness explained 98.4%of total variability in the microbial community composition.Soil organic carbon,total nitrogen,available potassium and soil water content were positively correlated with microbial community structure and biomass,whereas,soil hardness and silt content were negatively related to microbial community structure and biomass.This study provides new insights into microbial community structure and biomass that influence organic carbon,nitrogen,phosphorus and potassium accumulation,and clay content in soils at different stages of restoration.
基金supported by the National Natural Science Foundation of China(31830015,31901302).
文摘Background:Inputs of above-and belowground litter into forest soils are changing at an unprecedented rate due to continuing human disturbances and climate change.Microorganisms drive the soil carbon(C)cycle,but the roles of above-and belowground litter in regulating the soil microbial community have not been evaluated at a global scale.Methods:Here,we conducted a meta-analysis based on 68 aboveground litter removal and root exclusion studies across forest ecosystems to quantify the roles of above-and belowground litter on soil microbial community and compare their relative importance.Results:Aboveground litter removal significantly declined soil microbial biomass by 4.9%but root exclusion inhibited it stronger,up to 11.7%.Moreover,the aboveground litter removal significantly raised fungi by 10.1%without altering bacteria,leading to a 46.7%increase in the fungi-to-bacteria(F/B)ratio.Differently,root exclusion significantly decreased the fungi by 26.2%but increased the bacteria by 5.7%,causing a 13.3%decrease in the F/B ratio.Specifically,root exclusion significantly inhibited arbuscular mycorrhizal fungi,ectomycorrhizal fungi,and actinomycetes by 22.9%,43.8%,and 7.9%,respectively.The negative effects of aboveground litter removal on microbial biomass increased with mean annual temperature and precipitation,whereas that of root exclusion on microbial biomass did not change with climatic factors but amplified with treatment duration.More importantly,greater effects of root exclusion on microbial biomass than aboveground litter removal were consistent across diverse forest biomes(expect boreal forests)and durations.Conclusions:These data provide a global evidence that root litter inputs exert a larger control on microbial biomass than aboveground litter inputs in forest ecosystems.Our study also highlights that changes in above-and belowground litter inputs could alter soil C stability differently by shifting the microbial community structure in the opposite direction.These findings are useful for predicting microbe-mediated C processes in response to changes in forest management or climate.
文摘The effect of forests clear felling and associated burning on the population of soil nitrogen transforming bacteria and actinomycetes are reported at three pair sites of Chittagong University campus, Bangla- desh in monsoon tropical climate. Clear felled area or burnt site and 15-21 year mixed plantation of native and exotic species, situated side by side on low hill having Typic Dystrochrepts soil was represented at each pair site. At all the three pair sites, clear felled area or burnt site showed very significantly （p~_0.001） lower population of actinomycetes, Rhizobium, Nitrosomonas, Nitrobacter and ammonifying as well as deni- trifying bacteria compared to their adjacent mixed plantation. From en- vironmental consideration, this finding has implication in managing natural ecosystem.
基金This study was supported by the Open Project Program of State Key Laboratory of Petroleum Pollution Control(Grant No.PPC2019021)the Fundamental Reseach Funds for the central universities(22CX01004A-6)+1 种基金the CNPC Research Institute of Safety and Environmental Technology and CNPC Technology Innovation Fund Research Project(Grant Nos.2017D-5007-0601 and 2018D-5007-0605)the Research and Promotion Project of key technologies for safety and environmental protection of CNPC(2017D-4013).
文摘In this study,physicochemical,cluster,and high-throughput sequencing analyses were used to investigate the joint effects of salt and herbicide(glyphosate)stress factors on the microbial remediation of soil contaminated by n-hexadecane and phenanthrene.Based on the soil’s physical and chemical properties,differences in microbial quantity and enzyme activities were analyzed among the samples,and how that influenced distribution of soil community structure was focused upon.After 120 days of indoor simulated remediation,the cumulative degradation rate of n-hexadecane decreased by 94.92%(blank control),96.96%(low concentration salt and glyphosate stress group),65.07%(high concentration salt and glyphosate stress group),while that of phenanthrene decreased by 87.33%(blank control),86.25%(low concentration salt and glyphosate stress group),58.45%(high concentration salt and glyphosate stress group).The combined stress of salt and herbicides was capable of lowering the reduction efficiency of organic matter,total nitrogen,and total phosphorus,and also restricting the growth of microorganisms and enzyme activities.Cluster analysis results indicated that the non-stress group was similar to the low-concentration compound stress group during different remedial period,whereas both of those differed starkly from the high-concentration compound stress group.High-throughput sequencing revealed that the dominant soil bacteria phyla shifted from Firmicutes to Actinobacteria within 120 days of remediation.
文摘The microbial sulfur removal was investigated on high sulfur content (1.9%) coal concentrate from Tabas coal preparation plant. A mixed culture of ferrooxidans microorganisms was isolated from the tailing dam of the plant. Full factorial method was used to design laboratory test and to evaluate the effects of pH, particle size, iron sulfate concentration, pulp density, and bioleaching time on sulfur reduction. Statistical analyses of experimental data were considered and showed increases of pH and particle size had negative effects on sulfur reduction, whereas increases of pulp density and bioleaching time raised microbial desulfurization rate. According to results of designing, and regarding statistical factors, the optimum values for maximum sulfur reduction were obtained; pH (1.5), particle size (-180 μm), iron sulfate concentration (2.7 mmol/L), pulp density (10%) and bioleaching time (14 d), which leaded to 51.5% reduction from the total sulfur of sample.
文摘Use of legume trees can improve soil quality in degraded pastures. The aim of this study was to charac- terize C and N mineralization kinetics and estimate the potentially mineralizable C and N in soil under Mimosa caesalpiniifolia Benth. and Acacia auriculiformis A. Cunn. ex Benth. secondary forest and pasture in red-yellow latosols in southeast Brazil. We conducted a laboratory aerobic incubation experiment using a completely ran- domized design of four replicates and four types of plant cover using a modified version of the Stanford and Smith technique （1972） to study C and N mineralization potential. Potentially mineralizable N （No） ranged from 135 to 170 mg kg-1. The predominant form of mineral N for all types of plant cover was N-NO3-. M. caesalpiniifolia was the only species that had a positive influence on N min- eralization. Neither of the legumes influenced C mineral- ization in pasture or secondary forest. The model of N mineralization corresponded to a sigmoidal curve while C mineralization corresponded to an exponential curve, revealing that the N and C mineralization processes were distinct. N mineralized by M. caesalpiniifolia （216 kg ofN ha-1） was adequate to meet the N requirement for a livestock-forest system.
基金partially supported by the Special Funding for the Construction of Innovative Provinces in Hunan(2021SK4031)the Natural Science Foundation of Hunan Province(2022JJ50166)the Guidance Plan Project of Hengyang(hyzdxjh20213).
文摘Metabolic associated fatty liver disease(MAFLD)has become a prevalent chronic liver disease worldwide because of lifestyle and dietary changes.Gut microbiota and its metabolites have been shown to play a critical role in the pathogenesis of MAFLD.Understanding of the function of gut microbiota and its metabolites in MAFLD may help to elucidate pathological mechanisms,identify diagnostic markers,and develop drugs or probiotics for the treatment of MAFLD.Here we review the pathogenesis of MAFLD by gut microbiota and its metabolites and discuss the feasibility of treating MAFLD from the perspective of gut microbes.
文摘Isabel grape(IG)products have high contents of phenolic compounds and fiber recognized for their positive impacts on microorganisms associated with health benefits to host.This study evaluated the effects of goat yogurts formulated with ingredients from IG integral valorization on the growth and metabolism of different probiotic strains,as well as on the population of selected bacterial groups and metabolic activity of human colonic microbiota in vitro.Goat yogurts with IG ingredients(IGI)stimulated the growth of tested Lactobacillus and Bifidobacterium probiotic strains during a 48-h cultivation,as well as decreased the pH values and enhanced the organic acid production.Goat yogurts with IGI increased the population of Lactobacillus spp.and Bifidobacterium spp.during a 24-h in vitro colonic fermentation.A stable Firmicutes:Bacteroidetes ratio close to 1 was found in media with goat yogurt formulations during the colonic fermentation,being similar to the effect caused by fructooligosaccharides.Goat yogurt formulations with IGI caused increased production of short-chain fatty acids and sugar consumption during colonic fermentation.Goat yogurts with IGI should be a valuable strategy for development of novel added-value foods with beneficial effects on gut microbiota and human health.
基金This project was supported by the Knowledge Innovation Project from Chinese Academy （KZCXI-SW-01） and the National Natural Science Foundation of China （30070158）.
文摘Microorganism DNA of rhizosphere soil from Pinus koraiensis and Pinus sylvestriformis were extracted by proteinase K based on SDS method, CTAB method, PVP （polyvinylpolypyrrolidone） method, and freezing and thawing method and the crude DNA from rhizosphere soil were purified by dialysis method, silver beads absorption method, and squeezing DNA gel method. The results of different extracting and purifying methods were compared and evaluated. Results indicated that the best method of extraction for microorganism DNA in rhizosphere soil was proteinse K based on SDS method with high salt concentration of 1.0% （w/v） NaCl, which could effectively eliminate humic acids and other impurities. The dialysis method was suitable to purify DNA from rhizosphere soil because of effectively removing brown matters and humic acids and the purified products were suited to PCR amplification. Squeezing DNA gel method was also a good purification method with the advantage of inexpensive in cost and efficient in use.
基金financially supported by the National Natural Science Foundation of China (Grant No. 51408347, 51474140)the Scientific Research Fund Project of Introduced Talents (2014RCJJ015)+1 种基金Young Teachers Taleuts Training Plan (BJRC20170502) of Shandong University of Science and Technologythe Science and Technology Projects of Qingdao (Grant No. 15-9-1-58-jch and 15-9-1-32-jch)
文摘Oil pollution in marine environment is becoming increasingly serious. Oil bioremediation by immobilization technology has been widely studied. However, the effect of bacteria immobilization was limited because of lack of nutrients. In this paper, the organic materials(corn straw, corn cob and corn leaf) were used as carriers. The diesel removal rate achieved by the immobilized bacteria was studied, and the effects of nutrients(e.g. nitrogen and phosphorus) released from organic carriers to the immobilized bacteria were analyzed. Test results indicated that a certain amount of nutrients was released from organic carriers. Additionally, the diesel removal rates achieved by different immobilized bacteria were all higher than those achieved by free bacteria. And, the diesel removal rates achieved by bacteria decreased in the following order: bacteria immobilized on corn straw(79%), bacteria immobilized on corn leaf(70%) and bacteria immobilized on corn cob(43%). These findings indicated two aspects, viz.: the carriers porous structure and the nutrients, which were favorable to biodegradation. Finally, the changes in nitrogen and phosphorus contents that were released from different carriers during biodegradation were studied. The results showed that the rate of diesel biodegradation was fast in the initial phase because of the sufficient nutrients released from carriers. Meanwhile, in the final phase, the rate of diesel biodegradation was relatively slow because of few nutrients released from carriers.
