The eff ect of seasons on the soil microbiome in a Larix gmelinii forest of Mohe,China,where winter temperatures are generally below−40°C,was evaluated with metagenomics analysis.Taxonomic profi ling using sequen...The eff ect of seasons on the soil microbiome in a Larix gmelinii forest of Mohe,China,where winter temperatures are generally below−40°C,was evaluated with metagenomics analysis.Taxonomic profi ling using sequencing information revealed that Proteobacteria,Actinobacteria,Acidobacteria and Verrucomicrobia were the dominant phyla in spring,summer,and fall,as were Bradyrhizobium,Chthoniobacter,Streptomyces,Acid Candidatus Koribacter at the genus level.Some species that were abundant in spring and fall greatly diminished in abundance in summer.Clusters of orthologous groups(COG)of proteins,carbohydrate-active enzymes(CAZy),Kyoto Encyclopedia of Genes and Genomes(KEGG)and NCBI databases were used to elucidate the function of diverse proteins and metabolites of the microbial community of L.gmelinii forest.COG analysis showed that fewer genes were detected in spring than in fall and summer,indicating that many soil microbes in the L.gmelinii forest were not tolerant to cold.Based on KEGG analysis,some pathways in the soil microbes were activated in spring and autumn and deactivated in summer.CAZy analysis revealed that most CAZy were more active in summer than in spring or autumn and were severely inhibited in the spring.Many functional pathways,proteins,and CAZy involved in the community changes were concerned with cold or heat resistance.Therefore,the soil in the L.gmelinii forest can be a valuable resource for further research on heat and cold tolerance of soil microbes.展开更多
In the Loess Plateau of China,land-use pattern is a major factor in controlling underlying biological processes.Additionally,the process of land-use pattern was accompanied by abandoned lands,potentially impacting soi...In the Loess Plateau of China,land-use pattern is a major factor in controlling underlying biological processes.Additionally,the process of land-use pattern was accompanied by abandoned lands,potentially impacting soil microbe.However,limited researches were conducted to study the impacts of land-use patterns on the diversity and community of soil microorganisms in this area.The study aimed to investigate soil microbial community diversity and composition using high-throughput deoxyribonucleic acid(DNA)sequencing under different land-use patterns(apricot tree land,apple tree land,peach tree land,corn land,and abandoned land).The results showed a substantial difference(P<0.050)in bacterial alpha-diversity and beta-diversity between abandoned land and other land-use patterns,with the exception of Shannon index.While fungal beta-diversity was not considerably impacted by land-use patterns,fungal alpha-diversity indices varied significantly.The relative abundance of Actinobacteriota(34.90%),Proteobacteria(20.65%),and Ascomycota(77.42%)varied in soils with different land-use patterns.Soil pH exerted a dominant impact on the soil bacterial communities'composition,whereas soil available phosphorus was the main factor shaping the soil fungal communities'composition.These findings suggest that variations in land-use pattern had resulted in changes to soil properties,subsequently impacting diversity and structure of microbial community in the Loess Plateau.Given the strong interdependence between soil and its microbiota,it is imperative to reclaim abandoned lands to maintain soil fertility and sustain its function,which will have significant ecological service implications,particularly with regards to soil conservation in ecologically vulnerable areas.展开更多
Chinese hickory(Carya cathayensis Sarg.)is an important economic forest in Southeastern China.A large amount of hickory husk waste is generated every year but with a low proportion of returning.Meanwhile,intensive man...Chinese hickory(Carya cathayensis Sarg.)is an important economic forest in Southeastern China.A large amount of hickory husk waste is generated every year but with a low proportion of returning.Meanwhile,intensive management has resulted in soil degradation of Chinese hickory plantations.This study aims to investigate the effects of three Chinese hickory husk returning modes on soil amendment,including soil acidity,soil nutrition,and microbial community.The field experiment carried out four treatments:control(CK),hickory husk mulching(HM),hickory husk biochar(BC),and hickory husk organic fertilizer(OF).The phospholipid fatty acid(PLFA)biomarker method was employed to determine the soil microbial community.After one year of treatment,the results showed that:(i)HM and BC significantly increased soil pH by 0.33 and 1.71 units,respectively;(ii)HM,BC and OF treatments significantly increased the soil organic carbon,alkaline nitrogen,available phosphorous,and available potassium.The OF treatment demonstrated the most significant improvement in the soil nutrient;(iii)The soil microbial biomass significantly increased in the HM,BC and OF treatments,and all microbial groups showed an increasing trend.HM treatment increased the fungal/bacterial ratio(F/B).The OF treatment significantly decreased the Shannon-Wiener diversity(H’)and evenness index(J)of the microbial community(P<0.05).Considering the treatments effects,costs,and ease of operation,our recommended returning modes of Chinese hickory husk are mulching and organic fertilizer produced by composting with manure.展开更多
Afforestation has an important role in biodiversity conservation and ecosystem function improvement.A meta-analysis was carried out in China,which has the largest plantation area globally,to quantify the effects of pl...Afforestation has an important role in biodiversity conservation and ecosystem function improvement.A meta-analysis was carried out in China,which has the largest plantation area globally,to quantify the effects of plantings on soil microbial diversity.The results showed that the overall effect of afforestation on soil microbial diversity was positive across the country.Random forest algorithm suggested that soil carbon was the most important factor regulating microbial diversity and the positive response was only found with new plantings on low-carbon bare lands but not on high-carbon farmlands and grasslands.In addition,afforestation with broadleaved species increased microbial diversity,whereas planting with conifers had no effect on microbial diversity.This study clarified the effects of plantings on soil microbial diversity,which has an important implication for establishing appropriate policies and practices to improve the multiple functionalities(e.g.,biodiversity conservation and climate change mitigation)during plantation establishment.展开更多
Warming and nitrogen(N)deposition are two important drivers of global climate changes.Coarse woody debris(CWD)contains a large proportion of the carbon(C)in the total global C pool.The composition of soil microbial co...Warming and nitrogen(N)deposition are two important drivers of global climate changes.Coarse woody debris(CWD)contains a large proportion of the carbon(C)in the total global C pool.The composition of soil microbial communities and environmental changes(i.e.,N deposition and warming)are the key drivers of CWD decomposition,but the interactive impact between N deposition and warming on the composition of soil microbial communities and CWD decomposition is still unclear.In a laboratory experiment,we study and simulate respiration during decomposition of the CWD(C 98)of Cryptomeria japonica(CR)and Platycarya strobilacea(PL)in response to warming and N deposition over 98 days.Resuts show that either warming or N addition signifi cantly accelerated the C 98 of the two tree species by altering the soil microbial community(bacterial:fungi and G+:G–).The combined treatment(warming+N)resulted in a decomposition eff ect equal to the sum of the individual eff ects.In addition,the species composition of bacteria and fungi was obviously aff ected by warming.However,N deposition had a remarkable infl uence on G+:G–.Our results indicated that N deposition and warming will observably alter the composition and growth of the microbial community and thus work synergistically to accelerate CWD decomposition in forest ecosystems.We also present evidence that N deposition and warming infl uenced the composition and balance of soil microbial communities and biogeochemical cycling of forest ecosystems.展开更多
Aims Nitrogen(N)fertilization and lime addition may affect soil micro-bial and nematode communities and ecosystem functions through changing environmental conditions,such as soil pH and soil organic carbon.The objecti...Aims Nitrogen(N)fertilization and lime addition may affect soil micro-bial and nematode communities and ecosystem functions through changing environmental conditions,such as soil pH and soil organic carbon.The objectives of this experiment were to examine the impact of N input and liming on soil microbial and nematode communities and to identify the key environmental determinant of community composition in a century-old fertilization and crop rota-tion experiment.Methods The field experiment consisting of a 3-year crop rotation regime was established in 1911 in southeastern USA.Four treatments,(i)no-input control,(ii)NPK with winter legume,(iii)PK with legume and lime and(iv)NPK with legume and lime,were included in this study.soil samples collected at the 0-5 cm depth were used to determine the bacterial growth rate by the 3H-thymidine incorporation technique.Incorporation of 13C into neutral lipids,glycolipids and phospholipid fatty acids(PlFas)was measured after incubation of soil with 13C-labeled acetate for 24 h.Free-living nematodes in fresh soil were extracted using a density sucrose centrifugal flotation method and identified to trophic group level.Important Findingsliming resulted in a 10-fold increase in bacterial growth rates compared with the no-input control,whereas N fertilization had no significant effect.multivariate analysis of PlFa profiles showed that soil microbial community composition was different among the four treatments;the difference was primarily driven by soil pH.PlFas indicative of gram-negative bacteria covaried with soil pH,but not those of fungi and actinobacteria.liming enhanced 13C incorpora-tion into neutral lipids,glycolipids and phospholipids by 2-15 times.In addition,13C incorporation into 16:0,16:1ω9,18:1ω9,18:1ω7 and 18:2ω6 were greater than other PlFas,suggesting that gram-negative bacteria and fungi were more active and sensitive to simple C input.bacterivorous nematodes were the dominant trophic group in the soil,but no significant differences in nematode communities were found among the treatments.our results suggest that soil pH had a greater impact than N fertilization on soil microbial community composition and activity in a crop rotation system including legumes.展开更多
The alpine treeline ecotone is characterized as the upper limit of the forest in the high-mountain ecosystem.Due to the freeze-thaw cycles,the soil organism community,such as microbial communities are expected to chan...The alpine treeline ecotone is characterized as the upper limit of the forest in the high-mountain ecosystem.Due to the freeze-thaw cycles,the soil organism community,such as microbial communities are expected to change between seasons.However,there are limited microbialcommunity studies focused on the high altitude alpine ecosystem.We conducted a study in the alpine treeline ecotone on the eastern Qinghai-Tibet Plateau,China,and investigated the seasonal variability of the soil microbial community.We collected all soil samples within the alpine treeline ecotone,between the treeline and timberline in the high-mountain region.The 16S rRNA genes of the microbial communities(bacterial and archaeal)were analyzed by highthroughput sequencing to the genus level.The results showed that soil microbial community in the alpine treeline ecotone was consistently dominated by eight phyla which consisted of 95% of the total microbial community,including Proteobacteria,Actinobacteria,Acidobacteria,Firmicutes,Planctomycetes,Chloroflexi,Bacteroidetes,and Verrucomicrobia.The overall diversity and evenness of the community were relatively stable,with an average of 0.5% difference between seasons.The highest seasonal variability occurred at the upper boundary of the alpine treeline ecotone,and few or almost no seasonal change was observed at lower elevations,indicating dense forest cover and litter deposition might have created a local microclimate that reduced seasonal variation among the surrounding environmental conditions.Our study was one of the first group that documented the microbial community assemblage in the treeline ecotone on the Qinghai-Tibet Plateau.展开更多
The fertile forages in the Tibetan Plateau provide natural conditions for animal husbandry,whereas it is still unclear that whether animal excretion can result in the alteration of soil microbial community.Therefore,t...The fertile forages in the Tibetan Plateau provide natural conditions for animal husbandry,whereas it is still unclear that whether animal excretion can result in the alteration of soil microbial community.Therefore,this study was performed to investigate the impact of animal excretion contamination and land altitude on the soil microbial community in different grazing areas of Tibetan Plateau.A total of 1160,190 high-quality valid sequences and 25,478 operational taxonomic units were achieved from 18 samples at three different altitude sites(Linzhi,Rikaze and Shannan).Here,we found excremental contamination did not alter the richness and diversity of soil microbial community,but it resulted in a significant alteration in the proportion of some bacteria.Specifically,the proportion of Proteobacteria in the LZa was obviously increased,whereas Gemmatimonadetes was significantly decreased as compared to LZe.Moreover,significant difference can also be observed in Verrucomicrobia between RKZe and RKZa.Remarkably,we also found that excremental contamination significantly decreased the abundance of some bacterial genera,such as Sphingopyxis,Polycyclovorans,Singulisphaera Cohnella,Polycyclovorans,Defluviicoccus,and Arthrobacter,which were closely related to soil health,pollutant degradation,and nutrient metabolism.Importantly,excremental contamination increased the proportion of harmful and beneficial bacteria in soil,such as the percentage of Acidibacter,Gemmatimonadaceae and Pajaroellobacter increased,while the ratio of Pontibacter,Flavisolibacter,Parasegetibacter,and Niastella decreased.Remarkably,soil samples collected from different altitude sites also displayed different soil microbial community structures.Our results demonstrated that excremental contamination could alter the soil microbial community structure and affect the normal function of the soil by affecting the proportion of harmful bacteria to beneficial bacteria.Moreover,this study can also provide a theoretical basis for the establishment of a supervision system for soil quality in Tibet.展开更多
Soil microbial communities play an essential role in maintaining soil fertility and are considered as ecological indicators to evaluate soil health.In the present study,we examined the influence of almost 4 years of f...Soil microbial communities play an essential role in maintaining soil fertility and are considered as ecological indicators to evaluate soil health.In the present study,we examined the influence of almost 4 years of fertilization[no fertilizer(CK),nitrogen alone(N),nitrogen,phosphorus and potassium chemical fertilizer(NPK),organicmanure(M),nitrogen plus organic manure(NM),and NPK plus organic manure(NPKM)]on soil fertility and the functional diversity of soil microbial communities in an apple orchard.Compared to CK,fertilization increased soil organic carbon,total nitrogen,and available nutrients,but reduced soil pH in N and NPK treatments.The highest microbial biomass carbon and nitrogen,most probable number of actinomycetes,bacteria,and fungi occurred in the NPKM treatment.The average well color development(AWCD)values followed the order of NPKM>M>NPK and NM>CK and N.The Shannon index in organic manure treatments were significantly higher than in control and in treatments without organic manure.The principal component analysis showed that manure treatment was significantly separated from other treatments.These results indicated that organic manure applied alone or in combination with chemical fertilizers would increase soil fertility and functional diversity of soil microbial communities.Moreover,applying balanced N,P,K fertilizer in combination with organic manure was found to be superior to the use of a single fertilizer in improving soil microbial community quality.展开更多
The effects of supplementing 50%of the mineral N fertilizer with organic fertilizer on the metabolism and diversity of soil microbial communities in an oat field were investigated using Biolog-Eco plates.The experimen...The effects of supplementing 50%of the mineral N fertilizer with organic fertilizer on the metabolism and diversity of soil microbial communities in an oat field were investigated using Biolog-Eco plates.The experiment consisted of five treatments:no fertilizer(CK),mineral N fertilizer applied at 90 and 45 kg ha^(-1) N in the form of urea(U1 and U2,respectively),and U2 supplemented with organic fertilizer in the form of sheep manure at 90 and 45 kg ha^(-1) N(U2OM1 and U2OM2,respectively).Each treatment had three replications.The experiment was conducted in 2018 and 2019 in Pinglu District,Shanxi Province,China.The carbon source utilization by soil microbial communities,such as amino acids,amines,carbohydrates,carboxylic acids,and polymers,increased when 50%of the mineral N fertilizer was replaced with organic fertilizer in both years.This result was accompanied by increased richness,dominance,and evenness of the microbial communities.The utilization of amino acid,amine,and carboxylic acid carbon sources and community evenness were further improved when the organic fertilizer amount was doubled in both years.Biplot analysis indicated that amines and amino acids were the most representative of the total carbon source utilization by the soil microbial communities in both years.The highest oat yield was achieved at a total N application rate of 135 kg ha^(-1) in the treatment involving 45 kg ha^(-1) N in the form of urea and 90 kg ha^(-1) N in the form of sheep manure in both years.It was concluded that the application of 50%of the conventional rate of mineral N fertilizer supplemented with an appropriate rate of organic fertilizer enhanced both the functional diversity of soil microbial communities and oat yield.Amine and amino acid carbon sources may be used as a substitute for total carbon sources for assessing total carbon source utilization by soil microbial communities in oat fields in future studies.展开更多
Castanopsis fargesii is a good afforestation plants and various microorganisms play important roles in mediating the growth and ecological functions of this species.In this study,we evaluated changes in microbial comm...Castanopsis fargesii is a good afforestation plants and various microorganisms play important roles in mediating the growth and ecological functions of this species.In this study,we evaluated changes in microbial communities in soil samples from C.fargesii forests.The phospholipid fatty acid(PLFA)biomarker method was used to obtain bacteria,fungi,actinomycetes,gram-positive bacteria(G?),gram-negative bacteria(G-),aerobic bacteria,and anaerobic bacteria to investigate spatiotemporal changes in microbial communities during the growing season.The results show that soil microorganisms were mainly concentrated in the upper 20-cm layer,demonstrating an obvious surface aggregation(P<0.05).Large amounts of litter and heavy rainfall during the early growing season resulted in the highest PLFA contents for various microorganisms,whereas relatively low and stable levels were observed during other times.The dominant species during each period were bacteria.G+ or aerobic bacteria were the main bacterial populations,providing insights into the overall trends of soil bacterial PLFA contents.Due to the relative accumulation of refractory substances during the later stages of litter decomposition,the effects of fungi increased significantly.Overall,our findings demonstrate that the main factors influencing microbial communities were litter,rainfall,and soil field capacity.展开更多
Long-term deposition of atmospheric pollutants emitted from coal combustion and their effects on the eco-environment have been extensively studied around coal-fired power plants.However,the effects of coal-fired power...Long-term deposition of atmospheric pollutants emitted from coal combustion and their effects on the eco-environment have been extensively studied around coal-fired power plants.However,the effects of coal-fired power plants on soil microbial communities have received little attention through atmospheric pollutant deposition and coal-stacking.Here,we collected the samples of power plant soils(PS),coal-stacking soils(CSS)and agricultural soils(AS)around three coal-fired power plants and background control soils(BG)in Huainan,a typical mineral resource-based city in East China,and investigated the microbial diversity and community structures through a high-throughput sequencing technique.Coal-stacking significantly increased(p<0.05)the contents of total carbon,total nitrogen,total sulfur and Mo in the soils,whereas the deposition of atmospheric pollutants enhanced the levels of V,Cu,Zn and Pb.Proteobacteria,Actinobacteria,Thaumarchaeota,Thermoplasmata,Ascomycota and Basidiomycota were the dominant taxa in all soils.The bacterial community showed significant differences(p<0.05)among PS,CSS,AS and BG,whereas archaeal and fungal communities showed significant differences(p<0.01)according to soil samples around three coal-fired power plants.The predominant environmental variables affecting soil bacterial,archaeal and fungal communities were Mo-TN-TS,Cu-V-Mo,and organic matter(OM)-Mo,respectively.Certain soil microbial genera were closely related to multiple key factors associated with stacking coal and heavy metal deposition from power plants.This study provided useful insight into better understanding of the relationships between soil microbial communities and long-term disturbances from coal-fired power plants.展开更多
Silicon(Si) can increase plant resistance against bacterial wilt caused by Ralstonia solanacearum and enhance plant immune response. However, whether Si alleviates soil-borne disease stress through altering soil micro...Silicon(Si) can increase plant resistance against bacterial wilt caused by Ralstonia solanacearum and enhance plant immune response. However, whether Si alleviates soil-borne disease stress through altering soil microbial community component and diversity is not clear. In this study, effects of Si application under R. solanacearum inoculation with or without plant on soil bacterial and fungal communities were investigated through high-throughput pyrosequencing technique. The results showed that Si addition significantly reduced bacterial wilt incidence. However, Si did not reduce the amount of R. solanacearum in rhizosphere soil. Principal components analysis showed that soil microbial community composition was strongly influenced by Si addition. Total 63.7% bacterial operational taxonomic units(OTUs) and 43.8% fungal OTUs were regulated by Si addition regardless of the presence of tomato plants, indicating the independent effects of Si on soil microbial community. Si-added soil harbored a lower abundance of Fusarium, Pseudomonas, and Faecalibacterium. Our finding further demonstrated that exogenous Si could significantly influence soil microbial community component, and this may provide additional insight into the mechanism of Si-enhanced plant resistance against soil-borne pathogens.展开更多
Biological soil crusts(BSCs)are an important multi-trophic component of arid ecosystems in the Mediterranean region.In a mesocosm experiment,the authors investigated how the network of interactions among the members o...Biological soil crusts(BSCs)are an important multi-trophic component of arid ecosystems in the Mediterranean region.In a mesocosm experiment,the authors investigated how the network of interactions among the members of the soil microbial communities in four types of soil sample responded when soils were exposed to two simulated extreme rain events.The four types of soil samples were:covered by Cladonia rangiformis and previously hydrated(+BSC+H),covered by C.rangiformis and dried(+BSC-H),uncovered and hydrated(-BSC+H),uncovered and dried(-BSC-H).Network analysis was based on the co-occurrence patterns of microbes;microbes were assessed by the phospholipid fatty acids analysis.The authors further explored the relations between networks’metrics and soil functions denoted by enzymatic activity and soil chemical variables.All networks exhibited Small world properties,moderate values of clustering coefficient and eigen centrality,indicating the lack of hub nodes.The networks in-BSC-H soils appeared coherent during the pre-rain phases and they became modular after rains,while those in+BSC-H soils kept their connectivity till the second rain but this then collapsed.The network metrics that were indicative of cohesive networks tended to be related to enzyme activity while those that characterized the loose networks were related to Ca,K,Mg,NH_(4)^(+) and organic N.In all mesocosms except for+BSC-H,networks’fragmentation after the second heavy rain was milder than after the first one,supporting the idea of community acclimatization.The response of microbial networks to heavy rains was characterized by the tendency to exhibit degradation-reconstruction phases.The network collapse in the crusted only mesocosms showed that the communities beneath crusts in arid areas were extremely vulnerable to recurring heavy rain events.展开更多
Aims Forest disturbance from extreme weather events due to climate change could increase the contribution of fresh green leaves to the litter layer of soil and subsequently alter the composition and activity of the so...Aims Forest disturbance from extreme weather events due to climate change could increase the contribution of fresh green leaves to the litter layer of soil and subsequently alter the composition and activity of the soil microbial properties and soil carbon cycling.The objective of this study was to compare the effect of naturally fallen litter and fresh leaves on the soil microbial community composition and their activities.Methods Fresh leaves and normal fallen litter were collected from four tree species(Pinus elliottii,Schima superba,Acacia mangium,A.auriculaeformis)in subtropical China and mixed with soil.Soil microbial community composition was determined using PLFAs,and its activity was quantified by soil respiration.During a 12-month period,the decomposition rate of litter was measured bimonthly using a litterbag method.Soil microbial samples were collected after 6 and 12 months.Soil respiration was measured monthly.Important Findings We found that fresh leaves decomposed faster than their conspecific fallen litter.Although total microbial biomass and bacterial biomass were similar among treatments,soil fungal biomass was higher in fresh leaf than fallen litter treatments,resulting in greater values of the Fungal phospholipid fatty acids(PLFAs)/Bacterial PLFAs ratio.Fungal PLFA values were greater for Schima superba than the other species.The effect of litter type on soil respiration was species-dependent.Specifically,fallen litter released 35%more CO_(2) than fresh leaves of the conifer P.elliottii.The opposite pattern was observed in the broadleaf species whose fresh leaf treatments emitted 17%–32%more CO_(2) than fallen litter.Given future predictions that global climate change will cause more disturbances to forests,these results indicate that conifer and broadleaf forests in subtropical China may respond differently to increased fresh litter inputs,with net soil microbial respiration decreasing in conifer forests and increasing in broadleaf forests.展开更多
Soil respiration is a vital process in all terrestrial ecosystems,through which the soil releases carbon dioxide(CO_(2))into the atmosphere at an estimated annual rate of 68–101 Pg carbon,making it the second highest...Soil respiration is a vital process in all terrestrial ecosystems,through which the soil releases carbon dioxide(CO_(2))into the atmosphere at an estimated annual rate of 68–101 Pg carbon,making it the second highest terrestrial contributor to carbon fluxes.Since soil respiration consists of autotrophic and heterotrophic constituents,methods for accurately determining the contribution of each constituent to the total soil respiration are critical for understanding their differential responses to environmental factors and aiding the reduction of CO_(2)emissions.Owing to its low cost and simplicity,the root exclusion(RE)technique,combined with manual chamber measurements,is frequently used in field studies of soil respiration partitioning.Nevertheless,RE treatments alter the soil environment,leading to potential bias in respiration measurements.This review aims to elucidate the current understanding of RE,i.e.,trenching(Tr)and deep collar(DC)insertion techniques,by examining soil respiration partitioning studies performed in several ecosystems.Additionally,we discuss methodological considerations when using RE and the combinations of RE with stable isotopic and modeling approaches.Finally,future research directions for improving the Tr and DC insertion methods in RE are suggested.展开更多
As one of the most widely distributed bacterial predators in the soil, the role of bacterivorous nematodes on the enhanced bioremediation of polycyclic aromatic hydrocarbon-contaminated soils is crucial, but remains t...As one of the most widely distributed bacterial predators in the soil, the role of bacterivorous nematodes on the enhanced bioremediation of polycyclic aromatic hydrocarbon-contaminated soils is crucial, but remains to be investigated.A microcosm-level study was conducted to examine the effects of bacterial-feeding nematode grazing and tea saponin(TS) addition on bioremediation of a pyrene-contaminated soil enhanced by the polycyclic aromatic hydrocarbon(PAH)-degrading bacterial strain Sphingobium sp.PHE9.After 180 d of incubation, the highest pyrene dissipation(71.3%) was achieved through a combination of Sphingobium sp.PHE9 inoculation with nematode and TS addition.Meanwhile, high counts of culturable PAH-degrading bacteria, soil enzyme activity, and biodiversity indices were observed under the combined treatment, implying that the microbiological function of the contaminated soil was significantly restored.Additionally, the results of Tenax~ extraction with the first-order three-compartment model indicated that rate-limiting factors varied among treatments.The lack of degrading microorganisms was the main rate-limiting factor for the treatments involving TS/nematode addition, and inadequate bioaccessible pyrene was the vital rate-limiting factor in the treatments involving Sphingobium sp.PHE9 inoculation.The proposed combined clean-up strategy proved to be a promising bioremediation technology for aged pyrene-contaminated soils.展开更多
Aims Slash removal is a common practice to prepare recently harvested sites for replanting.However,little is known about its impact on soil carbon(C)dynamics in subtropical plantations.This study evaluates the effects...Aims Slash removal is a common practice to prepare recently harvested sites for replanting.However,little is known about its impact on soil carbon(C)dynamics in subtropical plantations.This study evaluates the effects of burning versus manual slash removal site preparation treatments on soil organic carbon(SOC),soil respiration and soil microbial community structure in a Pinus massoniana plantation in southern China.Methods Three areas within a mature P.massoniana plantation were clearcut.Two months following harvesting,slash on one-half of each area was burned(BURN),whereas slash was manually removed(MANR)on the other portion.Slash removal treatments were also compared with adjacent uncut plantation areas(UNCUT).Soil samples,and soil respiration measurements were used to characterize soil properties and microbial communities following slash removal treatments.Important Findings Mean soil respiration rates from the MANR and BURN treatments were 26%and 17%lower,respectively,than the UNCUT treatment over 1 year.The MANR and BURN treatment resulted in soils with 27%and 9%reduction in total phospholipid fatty acids(PLFAs)and 18%and 10%reduction in bacterial PLFAs,respectively,compared with the UNCUT treatment.However,no significant differences existed between slash removal treatments with respect to soil chemical properties,SOC chemical compositions,soil respiration and microbial communities;although PLFA patterns were notably different for the burned plots.Most factors affecting C dynamics and microbial communities were not sensitive to the differences imparted to the ecosystem due to manual slash removal or burning.Our results suggested that low-intensity burning after clear-cutting might have no significant effect on soil C pool and its dynamics compared with manual slash removal in subtropical plantations.展开更多
A vertical-flow constructed wetland(VFCW)was used to treat simulated domestic sewage containing perfluorooctane sulfonate(PFOS).The removal rate of PFOS in the domestic sewage was 93%–98%,through soil adsorption and ...A vertical-flow constructed wetland(VFCW)was used to treat simulated domestic sewage containing perfluorooctane sulfonate(PFOS).The removal rate of PFOS in the domestic sewage was 93%–98%,through soil adsorption and plant uptake,suggesting that VFCWs can remove PFOS efficiently from wastewater.The removal of PFOS in the VFCW was dependent on soil adsorption and plant uptake;moreover,the percentage of soil adsorption was 61%–89%,and was higher than that of the plants uptake(5%–31%).The absorption capacity of Eichhornia crassipes(E.crassipes)(1186.71 mg/kg)was higher than that of Cyperus alternifolius(C.alternifolius)(162.77 mg/kg)under 10 mg/L PFOS,and the transfer factor of PFOS in E.crassipes and C.alternifolius was 0.04 and 0.58,respectively,indicating that PFOS is not easily translocated to leaves from roots of wetland plants;moreover,uptake of PFOS by E.crassipes was more than that of C.alternifolius because the biomass of E.crassipes was more than that of C.alternifolius and the roots of E.crassipes can take up PFOS directly from wastewater while C.alternifolius needs to do so via its roots in the soil.The concentration of 10 mg/L PFOS had an obvious inhibitory effect on the removal rate of total nitrogen,total phosphorus,chemical oxygen demand,and ammonia nitrogen in the VFCW,which decreased by 15%,10%,10%and 12%,respectively.Dosing with PFOS in the wastewater reduced the bacterial richness but increased the diversity in soil because PFOS stimulated the growth of PFOS-tolerant strains.展开更多
Polycyclic aromatic hydrocarbons(PAHs)are ubiquitous priority pollutants that cause great damage to the natural environment and health.Average genome size in a community is critical for shedding light on microbiome...Polycyclic aromatic hydrocarbons(PAHs)are ubiquitous priority pollutants that cause great damage to the natural environment and health.Average genome size in a community is critical for shedding light on microbiome's functional response to pollution stress within an environment.Here,microcosms under different concentrations were performed to evaluate the selection of PAHs stress on the average genome size in a community.We found the distinct communities of significantly larger genome size with the increase of PAHs concentration gradients in soils,and consistent trends were discovered in soils at different latitudes.The abundance of Proteobacteria and Deinococcus-Thermus with relatively larger genomes increased along with PAHs stress and well adapted to polluted environments.In contrast,the abundance of Patescibacteria with a highly streamlined and smaller genome decreased,implying complex interactions between environmental selection and functional fitness resulted in bacteria with larger genomes becoming more abundant.Moreover,we confirmed the increased capacity for horizontal transfer of degrading genes between communities by showing an increased connection number per node positively related to the nid A gene along the concentration gradients in the co-occurrence network.Our findings suggest PAHs tend to select bacterial taxa with larger genome sizes,with significant consequences for community stability and potential biodegradation strategies.展开更多
基金the National Natural Science Foundation of China(No.31670494).
文摘The eff ect of seasons on the soil microbiome in a Larix gmelinii forest of Mohe,China,where winter temperatures are generally below−40°C,was evaluated with metagenomics analysis.Taxonomic profi ling using sequencing information revealed that Proteobacteria,Actinobacteria,Acidobacteria and Verrucomicrobia were the dominant phyla in spring,summer,and fall,as were Bradyrhizobium,Chthoniobacter,Streptomyces,Acid Candidatus Koribacter at the genus level.Some species that were abundant in spring and fall greatly diminished in abundance in summer.Clusters of orthologous groups(COG)of proteins,carbohydrate-active enzymes(CAZy),Kyoto Encyclopedia of Genes and Genomes(KEGG)and NCBI databases were used to elucidate the function of diverse proteins and metabolites of the microbial community of L.gmelinii forest.COG analysis showed that fewer genes were detected in spring than in fall and summer,indicating that many soil microbes in the L.gmelinii forest were not tolerant to cold.Based on KEGG analysis,some pathways in the soil microbes were activated in spring and autumn and deactivated in summer.CAZy analysis revealed that most CAZy were more active in summer than in spring or autumn and were severely inhibited in the spring.Many functional pathways,proteins,and CAZy involved in the community changes were concerned with cold or heat resistance.Therefore,the soil in the L.gmelinii forest can be a valuable resource for further research on heat and cold tolerance of soil microbes.
基金supported by the Science and Technology Planning Project of Gansu Province,China(23ZDKA017).
文摘In the Loess Plateau of China,land-use pattern is a major factor in controlling underlying biological processes.Additionally,the process of land-use pattern was accompanied by abandoned lands,potentially impacting soil microbe.However,limited researches were conducted to study the impacts of land-use patterns on the diversity and community of soil microorganisms in this area.The study aimed to investigate soil microbial community diversity and composition using high-throughput deoxyribonucleic acid(DNA)sequencing under different land-use patterns(apricot tree land,apple tree land,peach tree land,corn land,and abandoned land).The results showed a substantial difference(P<0.050)in bacterial alpha-diversity and beta-diversity between abandoned land and other land-use patterns,with the exception of Shannon index.While fungal beta-diversity was not considerably impacted by land-use patterns,fungal alpha-diversity indices varied significantly.The relative abundance of Actinobacteriota(34.90%),Proteobacteria(20.65%),and Ascomycota(77.42%)varied in soils with different land-use patterns.Soil pH exerted a dominant impact on the soil bacterial communities'composition,whereas soil available phosphorus was the main factor shaping the soil fungal communities'composition.These findings suggest that variations in land-use pattern had resulted in changes to soil properties,subsequently impacting diversity and structure of microbial community in the Loess Plateau.Given the strong interdependence between soil and its microbiota,it is imperative to reclaim abandoned lands to maintain soil fertility and sustain its function,which will have significant ecological service implications,particularly with regards to soil conservation in ecologically vulnerable areas.
基金financially supported by Natural Science Foundation of Zhejiang Province(LY20C160003)the National College Students’Innovation and Entrepreneurship Training Program(202110341063).
文摘Chinese hickory(Carya cathayensis Sarg.)is an important economic forest in Southeastern China.A large amount of hickory husk waste is generated every year but with a low proportion of returning.Meanwhile,intensive management has resulted in soil degradation of Chinese hickory plantations.This study aims to investigate the effects of three Chinese hickory husk returning modes on soil amendment,including soil acidity,soil nutrition,and microbial community.The field experiment carried out four treatments:control(CK),hickory husk mulching(HM),hickory husk biochar(BC),and hickory husk organic fertilizer(OF).The phospholipid fatty acid(PLFA)biomarker method was employed to determine the soil microbial community.After one year of treatment,the results showed that:(i)HM and BC significantly increased soil pH by 0.33 and 1.71 units,respectively;(ii)HM,BC and OF treatments significantly increased the soil organic carbon,alkaline nitrogen,available phosphorous,and available potassium.The OF treatment demonstrated the most significant improvement in the soil nutrient;(iii)The soil microbial biomass significantly increased in the HM,BC and OF treatments,and all microbial groups showed an increasing trend.HM treatment increased the fungal/bacterial ratio(F/B).The OF treatment significantly decreased the Shannon-Wiener diversity(H’)and evenness index(J)of the microbial community(P<0.05).Considering the treatments effects,costs,and ease of operation,our recommended returning modes of Chinese hickory husk are mulching and organic fertilizer produced by composting with manure.
基金supported by the National Key Research and Development Program of China(2021YFD2200401)the National Natural Science Foundation of China(31901293)。
文摘Afforestation has an important role in biodiversity conservation and ecosystem function improvement.A meta-analysis was carried out in China,which has the largest plantation area globally,to quantify the effects of plantings on soil microbial diversity.The results showed that the overall effect of afforestation on soil microbial diversity was positive across the country.Random forest algorithm suggested that soil carbon was the most important factor regulating microbial diversity and the positive response was only found with new plantings on low-carbon bare lands but not on high-carbon farmlands and grasslands.In addition,afforestation with broadleaved species increased microbial diversity,whereas planting with conifers had no effect on microbial diversity.This study clarified the effects of plantings on soil microbial diversity,which has an important implication for establishing appropriate policies and practices to improve the multiple functionalities(e.g.,biodiversity conservation and climate change mitigation)during plantation establishment.
基金supported by the National Natural Science Foundation of China(3196140162).
文摘Warming and nitrogen(N)deposition are two important drivers of global climate changes.Coarse woody debris(CWD)contains a large proportion of the carbon(C)in the total global C pool.The composition of soil microbial communities and environmental changes(i.e.,N deposition and warming)are the key drivers of CWD decomposition,but the interactive impact between N deposition and warming on the composition of soil microbial communities and CWD decomposition is still unclear.In a laboratory experiment,we study and simulate respiration during decomposition of the CWD(C 98)of Cryptomeria japonica(CR)and Platycarya strobilacea(PL)in response to warming and N deposition over 98 days.Resuts show that either warming or N addition signifi cantly accelerated the C 98 of the two tree species by altering the soil microbial community(bacterial:fungi and G+:G–).The combined treatment(warming+N)resulted in a decomposition eff ect equal to the sum of the individual eff ects.In addition,the species composition of bacteria and fungi was obviously aff ected by warming.However,N deposition had a remarkable infl uence on G+:G–.Our results indicated that N deposition and warming will observably alter the composition and growth of the microbial community and thus work synergistically to accelerate CWD decomposition in forest ecosystems.We also present evidence that N deposition and warming infl uenced the composition and balance of soil microbial communities and biogeochemical cycling of forest ecosystems.
基金Alabama Agricultural Land Grant Alliancethe Alabama Agricultural Experiment Station+1 种基金National Science Foundation of China(31200408,30925010)National Science Foundation of China-Guangdong Joint Project(U1131001).
文摘Aims Nitrogen(N)fertilization and lime addition may affect soil micro-bial and nematode communities and ecosystem functions through changing environmental conditions,such as soil pH and soil organic carbon.The objectives of this experiment were to examine the impact of N input and liming on soil microbial and nematode communities and to identify the key environmental determinant of community composition in a century-old fertilization and crop rota-tion experiment.Methods The field experiment consisting of a 3-year crop rotation regime was established in 1911 in southeastern USA.Four treatments,(i)no-input control,(ii)NPK with winter legume,(iii)PK with legume and lime and(iv)NPK with legume and lime,were included in this study.soil samples collected at the 0-5 cm depth were used to determine the bacterial growth rate by the 3H-thymidine incorporation technique.Incorporation of 13C into neutral lipids,glycolipids and phospholipid fatty acids(PlFas)was measured after incubation of soil with 13C-labeled acetate for 24 h.Free-living nematodes in fresh soil were extracted using a density sucrose centrifugal flotation method and identified to trophic group level.Important Findingsliming resulted in a 10-fold increase in bacterial growth rates compared with the no-input control,whereas N fertilization had no significant effect.multivariate analysis of PlFa profiles showed that soil microbial community composition was different among the four treatments;the difference was primarily driven by soil pH.PlFas indicative of gram-negative bacteria covaried with soil pH,but not those of fungi and actinobacteria.liming enhanced 13C incorpora-tion into neutral lipids,glycolipids and phospholipids by 2-15 times.In addition,13C incorporation into 16:0,16:1ω9,18:1ω9,18:1ω7 and 18:2ω6 were greater than other PlFas,suggesting that gram-negative bacteria and fungi were more active and sensitive to simple C input.bacterivorous nematodes were the dominant trophic group in the soil,but no significant differences in nematode communities were found among the treatments.our results suggest that soil pH had a greater impact than N fertilization on soil microbial community composition and activity in a crop rotation system including legumes.
基金funded by the National Natural Science Foundation of China(NSFC,No.41271094 and No.40871124).
文摘The alpine treeline ecotone is characterized as the upper limit of the forest in the high-mountain ecosystem.Due to the freeze-thaw cycles,the soil organism community,such as microbial communities are expected to change between seasons.However,there are limited microbialcommunity studies focused on the high altitude alpine ecosystem.We conducted a study in the alpine treeline ecotone on the eastern Qinghai-Tibet Plateau,China,and investigated the seasonal variability of the soil microbial community.We collected all soil samples within the alpine treeline ecotone,between the treeline and timberline in the high-mountain region.The 16S rRNA genes of the microbial communities(bacterial and archaeal)were analyzed by highthroughput sequencing to the genus level.The results showed that soil microbial community in the alpine treeline ecotone was consistently dominated by eight phyla which consisted of 95% of the total microbial community,including Proteobacteria,Actinobacteria,Acidobacteria,Firmicutes,Planctomycetes,Chloroflexi,Bacteroidetes,and Verrucomicrobia.The overall diversity and evenness of the community were relatively stable,with an average of 0.5% difference between seasons.The highest seasonal variability occurred at the upper boundary of the alpine treeline ecotone,and few or almost no seasonal change was observed at lower elevations,indicating dense forest cover and litter deposition might have created a local microclimate that reduced seasonal variation among the surrounding environmental conditions.Our study was one of the first group that documented the microbial community assemblage in the treeline ecotone on the Qinghai-Tibet Plateau.
基金The study was supported by Key research,Development and Transformation Program of Tibet Autonomous Region(XZ201902NB05)Research and Demonstration of Technologies for Prevention and Control of Major Infectious Diseases in Characteristic Livestock(XZ201901NA02)the Outstanding Young Talents Project of South China Agricultural University.
文摘The fertile forages in the Tibetan Plateau provide natural conditions for animal husbandry,whereas it is still unclear that whether animal excretion can result in the alteration of soil microbial community.Therefore,this study was performed to investigate the impact of animal excretion contamination and land altitude on the soil microbial community in different grazing areas of Tibetan Plateau.A total of 1160,190 high-quality valid sequences and 25,478 operational taxonomic units were achieved from 18 samples at three different altitude sites(Linzhi,Rikaze and Shannan).Here,we found excremental contamination did not alter the richness and diversity of soil microbial community,but it resulted in a significant alteration in the proportion of some bacteria.Specifically,the proportion of Proteobacteria in the LZa was obviously increased,whereas Gemmatimonadetes was significantly decreased as compared to LZe.Moreover,significant difference can also be observed in Verrucomicrobia between RKZe and RKZa.Remarkably,we also found that excremental contamination significantly decreased the abundance of some bacterial genera,such as Sphingopyxis,Polycyclovorans,Singulisphaera Cohnella,Polycyclovorans,Defluviicoccus,and Arthrobacter,which were closely related to soil health,pollutant degradation,and nutrient metabolism.Importantly,excremental contamination increased the proportion of harmful and beneficial bacteria in soil,such as the percentage of Acidibacter,Gemmatimonadaceae and Pajaroellobacter increased,while the ratio of Pontibacter,Flavisolibacter,Parasegetibacter,and Niastella decreased.Remarkably,soil samples collected from different altitude sites also displayed different soil microbial community structures.Our results demonstrated that excremental contamination could alter the soil microbial community structure and affect the normal function of the soil by affecting the proportion of harmful bacteria to beneficial bacteria.Moreover,this study can also provide a theoretical basis for the establishment of a supervision system for soil quality in Tibet.
基金This work was supported by the Special Fund for the National Key R&D Programof China(Grant No.2016YFD0201100)National Natural Science Foundation of China(Grant No.31501713)+1 种基金China Agriculture Research System(Grant No.CARS-27)and Taishan Scholar Assistance Program from Shandong Provincial Government.
文摘Soil microbial communities play an essential role in maintaining soil fertility and are considered as ecological indicators to evaluate soil health.In the present study,we examined the influence of almost 4 years of fertilization[no fertilizer(CK),nitrogen alone(N),nitrogen,phosphorus and potassium chemical fertilizer(NPK),organicmanure(M),nitrogen plus organic manure(NM),and NPK plus organic manure(NPKM)]on soil fertility and the functional diversity of soil microbial communities in an apple orchard.Compared to CK,fertilization increased soil organic carbon,total nitrogen,and available nutrients,but reduced soil pH in N and NPK treatments.The highest microbial biomass carbon and nitrogen,most probable number of actinomycetes,bacteria,and fungi occurred in the NPKM treatment.The average well color development(AWCD)values followed the order of NPKM>M>NPK and NM>CK and N.The Shannon index in organic manure treatments were significantly higher than in control and in treatments without organic manure.The principal component analysis showed that manure treatment was significantly separated from other treatments.These results indicated that organic manure applied alone or in combination with chemical fertilizers would increase soil fertility and functional diversity of soil microbial communities.Moreover,applying balanced N,P,K fertilizer in combination with organic manure was found to be superior to the use of a single fertilizer in improving soil microbial community quality.
基金This research was supported by the Key Research and Development Program of Shanxi Province,China(201703D211001-03-01 and 201703D211001-03-03)and the Key Research and Development Program of Shanxi Province,China(201903D221061).
文摘The effects of supplementing 50%of the mineral N fertilizer with organic fertilizer on the metabolism and diversity of soil microbial communities in an oat field were investigated using Biolog-Eco plates.The experiment consisted of five treatments:no fertilizer(CK),mineral N fertilizer applied at 90 and 45 kg ha^(-1) N in the form of urea(U1 and U2,respectively),and U2 supplemented with organic fertilizer in the form of sheep manure at 90 and 45 kg ha^(-1) N(U2OM1 and U2OM2,respectively).Each treatment had three replications.The experiment was conducted in 2018 and 2019 in Pinglu District,Shanxi Province,China.The carbon source utilization by soil microbial communities,such as amino acids,amines,carbohydrates,carboxylic acids,and polymers,increased when 50%of the mineral N fertilizer was replaced with organic fertilizer in both years.This result was accompanied by increased richness,dominance,and evenness of the microbial communities.The utilization of amino acid,amine,and carboxylic acid carbon sources and community evenness were further improved when the organic fertilizer amount was doubled in both years.Biplot analysis indicated that amines and amino acids were the most representative of the total carbon source utilization by the soil microbial communities in both years.The highest oat yield was achieved at a total N application rate of 135 kg ha^(-1) in the treatment involving 45 kg ha^(-1) N in the form of urea and 90 kg ha^(-1) N in the form of sheep manure in both years.It was concluded that the application of 50%of the conventional rate of mineral N fertilizer supplemented with an appropriate rate of organic fertilizer enhanced both the functional diversity of soil microbial communities and oat yield.Amine and amino acid carbon sources may be used as a substitute for total carbon sources for assessing total carbon source utilization by soil microbial communities in oat fields in future studies.
基金This study was supported by the Science and Technology Basic Work Special(No 2014FY120700).
文摘Castanopsis fargesii is a good afforestation plants and various microorganisms play important roles in mediating the growth and ecological functions of this species.In this study,we evaluated changes in microbial communities in soil samples from C.fargesii forests.The phospholipid fatty acid(PLFA)biomarker method was used to obtain bacteria,fungi,actinomycetes,gram-positive bacteria(G?),gram-negative bacteria(G-),aerobic bacteria,and anaerobic bacteria to investigate spatiotemporal changes in microbial communities during the growing season.The results show that soil microorganisms were mainly concentrated in the upper 20-cm layer,demonstrating an obvious surface aggregation(P<0.05).Large amounts of litter and heavy rainfall during the early growing season resulted in the highest PLFA contents for various microorganisms,whereas relatively low and stable levels were observed during other times.The dominant species during each period were bacteria.G+ or aerobic bacteria were the main bacterial populations,providing insights into the overall trends of soil bacterial PLFA contents.Due to the relative accumulation of refractory substances during the later stages of litter decomposition,the effects of fungi increased significantly.Overall,our findings demonstrate that the main factors influencing microbial communities were litter,rainfall,and soil field capacity.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences (No.XDB40010200)the National Natural Science Foundation of China (Nos.41976220 and 41776190)the National Key Research and Development Program of China (No.2020YFA0608501)。
文摘Long-term deposition of atmospheric pollutants emitted from coal combustion and their effects on the eco-environment have been extensively studied around coal-fired power plants.However,the effects of coal-fired power plants on soil microbial communities have received little attention through atmospheric pollutant deposition and coal-stacking.Here,we collected the samples of power plant soils(PS),coal-stacking soils(CSS)and agricultural soils(AS)around three coal-fired power plants and background control soils(BG)in Huainan,a typical mineral resource-based city in East China,and investigated the microbial diversity and community structures through a high-throughput sequencing technique.Coal-stacking significantly increased(p<0.05)the contents of total carbon,total nitrogen,total sulfur and Mo in the soils,whereas the deposition of atmospheric pollutants enhanced the levels of V,Cu,Zn and Pb.Proteobacteria,Actinobacteria,Thaumarchaeota,Thermoplasmata,Ascomycota and Basidiomycota were the dominant taxa in all soils.The bacterial community showed significant differences(p<0.05)among PS,CSS,AS and BG,whereas archaeal and fungal communities showed significant differences(p<0.01)according to soil samples around three coal-fired power plants.The predominant environmental variables affecting soil bacterial,archaeal and fungal communities were Mo-TN-TS,Cu-V-Mo,and organic matter(OM)-Mo,respectively.Certain soil microbial genera were closely related to multiple key factors associated with stacking coal and heavy metal deposition from power plants.This study provided useful insight into better understanding of the relationships between soil microbial communities and long-term disturbances from coal-fired power plants.
基金financially supported by grants from the National Natural Science Foundation of China (31370456)the Doctoral Foundation of the Ministry of Education of China (20124404110007)+1 种基金the Natural Science Foundation of Guangdong Province of China (S2012010010331 and 2017A030313177)the Project of International, as well as Hong Kong, Macao & Taiwan Science and Technology Cooperation Innovation Platform in Universities in Guangdong Province, China (2014KGJHZ004)
文摘Silicon(Si) can increase plant resistance against bacterial wilt caused by Ralstonia solanacearum and enhance plant immune response. However, whether Si alleviates soil-borne disease stress through altering soil microbial community component and diversity is not clear. In this study, effects of Si application under R. solanacearum inoculation with or without plant on soil bacterial and fungal communities were investigated through high-throughput pyrosequencing technique. The results showed that Si addition significantly reduced bacterial wilt incidence. However, Si did not reduce the amount of R. solanacearum in rhizosphere soil. Principal components analysis showed that soil microbial community composition was strongly influenced by Si addition. Total 63.7% bacterial operational taxonomic units(OTUs) and 43.8% fungal OTUs were regulated by Si addition regardless of the presence of tomato plants, indicating the independent effects of Si on soil microbial community. Si-added soil harbored a lower abundance of Fusarium, Pseudomonas, and Faecalibacterium. Our finding further demonstrated that exogenous Si could significantly influence soil microbial community component, and this may provide additional insight into the mechanism of Si-enhanced plant resistance against soil-borne pathogens.
文摘Biological soil crusts(BSCs)are an important multi-trophic component of arid ecosystems in the Mediterranean region.In a mesocosm experiment,the authors investigated how the network of interactions among the members of the soil microbial communities in four types of soil sample responded when soils were exposed to two simulated extreme rain events.The four types of soil samples were:covered by Cladonia rangiformis and previously hydrated(+BSC+H),covered by C.rangiformis and dried(+BSC-H),uncovered and hydrated(-BSC+H),uncovered and dried(-BSC-H).Network analysis was based on the co-occurrence patterns of microbes;microbes were assessed by the phospholipid fatty acids analysis.The authors further explored the relations between networks’metrics and soil functions denoted by enzymatic activity and soil chemical variables.All networks exhibited Small world properties,moderate values of clustering coefficient and eigen centrality,indicating the lack of hub nodes.The networks in-BSC-H soils appeared coherent during the pre-rain phases and they became modular after rains,while those in+BSC-H soils kept their connectivity till the second rain but this then collapsed.The network metrics that were indicative of cohesive networks tended to be related to enzyme activity while those that characterized the loose networks were related to Ca,K,Mg,NH_(4)^(+) and organic N.In all mesocosms except for+BSC-H,networks’fragmentation after the second heavy rain was milder than after the first one,supporting the idea of community acclimatization.The response of microbial networks to heavy rains was characterized by the tendency to exhibit degradation-reconstruction phases.The network collapse in the crusted only mesocosms showed that the communities beneath crusts in arid areas were extremely vulnerable to recurring heavy rain events.
基金National Natural Science Foundation of China(30870442)National Basic Research Program of China(2009CB421101 and 2011CB403200)+3 种基金NSFC-Guangdong Joint Project(U1131001)Guangdong Natural Science Foundation(S2011040005712)the Knowledge Innovation Program of the Chinese Academy of Sciences(KSCX2-EW-J-28)the‘Strategic Priority Research Program-Climate Change:Carbon Budget and Related Issues’of the Chinese Academy of Sciences(XDA05070307).
文摘Aims Forest disturbance from extreme weather events due to climate change could increase the contribution of fresh green leaves to the litter layer of soil and subsequently alter the composition and activity of the soil microbial properties and soil carbon cycling.The objective of this study was to compare the effect of naturally fallen litter and fresh leaves on the soil microbial community composition and their activities.Methods Fresh leaves and normal fallen litter were collected from four tree species(Pinus elliottii,Schima superba,Acacia mangium,A.auriculaeformis)in subtropical China and mixed with soil.Soil microbial community composition was determined using PLFAs,and its activity was quantified by soil respiration.During a 12-month period,the decomposition rate of litter was measured bimonthly using a litterbag method.Soil microbial samples were collected after 6 and 12 months.Soil respiration was measured monthly.Important Findings We found that fresh leaves decomposed faster than their conspecific fallen litter.Although total microbial biomass and bacterial biomass were similar among treatments,soil fungal biomass was higher in fresh leaf than fallen litter treatments,resulting in greater values of the Fungal phospholipid fatty acids(PLFAs)/Bacterial PLFAs ratio.Fungal PLFA values were greater for Schima superba than the other species.The effect of litter type on soil respiration was species-dependent.Specifically,fallen litter released 35%more CO_(2) than fresh leaves of the conifer P.elliottii.The opposite pattern was observed in the broadleaf species whose fresh leaf treatments emitted 17%–32%more CO_(2) than fallen litter.Given future predictions that global climate change will cause more disturbances to forests,these results indicate that conifer and broadleaf forests in subtropical China may respond differently to increased fresh litter inputs,with net soil microbial respiration decreasing in conifer forests and increasing in broadleaf forests.
文摘Soil respiration is a vital process in all terrestrial ecosystems,through which the soil releases carbon dioxide(CO_(2))into the atmosphere at an estimated annual rate of 68–101 Pg carbon,making it the second highest terrestrial contributor to carbon fluxes.Since soil respiration consists of autotrophic and heterotrophic constituents,methods for accurately determining the contribution of each constituent to the total soil respiration are critical for understanding their differential responses to environmental factors and aiding the reduction of CO_(2)emissions.Owing to its low cost and simplicity,the root exclusion(RE)technique,combined with manual chamber measurements,is frequently used in field studies of soil respiration partitioning.Nevertheless,RE treatments alter the soil environment,leading to potential bias in respiration measurements.This review aims to elucidate the current understanding of RE,i.e.,trenching(Tr)and deep collar(DC)insertion techniques,by examining soil respiration partitioning studies performed in several ecosystems.Additionally,we discuss methodological considerations when using RE and the combinations of RE with stable isotopic and modeling approaches.Finally,future research directions for improving the Tr and DC insertion methods in RE are suggested.
基金financially supported by the National Natural Science Foundation of China(Nos.41371263 and 41771350)the Fundamental Research Funds for the Central Universities of China(Nos.KYTZ201404 and Y0201700160)+3 种基金the Agricultural Science and Technology Innovation Fund of Jiangsu Province,China(No.CX(17)3047)the Agro-scientific Research in the Public Interest of China(No.201503121)the Environmental Protection Research Project in Jiangsu Province,China(No.2017005)the National Key Research and Development Program of China(Nos.2016YFD0200106 and 2016YFD0300908)
文摘As one of the most widely distributed bacterial predators in the soil, the role of bacterivorous nematodes on the enhanced bioremediation of polycyclic aromatic hydrocarbon-contaminated soils is crucial, but remains to be investigated.A microcosm-level study was conducted to examine the effects of bacterial-feeding nematode grazing and tea saponin(TS) addition on bioremediation of a pyrene-contaminated soil enhanced by the polycyclic aromatic hydrocarbon(PAH)-degrading bacterial strain Sphingobium sp.PHE9.After 180 d of incubation, the highest pyrene dissipation(71.3%) was achieved through a combination of Sphingobium sp.PHE9 inoculation with nematode and TS addition.Meanwhile, high counts of culturable PAH-degrading bacteria, soil enzyme activity, and biodiversity indices were observed under the combined treatment, implying that the microbiological function of the contaminated soil was significantly restored.Additionally, the results of Tenax~ extraction with the first-order three-compartment model indicated that rate-limiting factors varied among treatments.The lack of degrading microorganisms was the main rate-limiting factor for the treatments involving TS/nematode addition, and inadequate bioaccessible pyrene was the vital rate-limiting factor in the treatments involving Sphingobium sp.PHE9 inoculation.The proposed combined clean-up strategy proved to be a promising bioremediation technology for aged pyrene-contaminated soils.
基金Ministry of Science and Technology(2012BAD22B01 and 2015DFA31440)China’s National Natural Science Foundation(31290223)+1 种基金the Ministry of Finance(200804001 and 201104006)the Lecture and Study Program for Outstanding Scholars from Home and Abroad(CAFYBB2011007)。
文摘Aims Slash removal is a common practice to prepare recently harvested sites for replanting.However,little is known about its impact on soil carbon(C)dynamics in subtropical plantations.This study evaluates the effects of burning versus manual slash removal site preparation treatments on soil organic carbon(SOC),soil respiration and soil microbial community structure in a Pinus massoniana plantation in southern China.Methods Three areas within a mature P.massoniana plantation were clearcut.Two months following harvesting,slash on one-half of each area was burned(BURN),whereas slash was manually removed(MANR)on the other portion.Slash removal treatments were also compared with adjacent uncut plantation areas(UNCUT).Soil samples,and soil respiration measurements were used to characterize soil properties and microbial communities following slash removal treatments.Important Findings Mean soil respiration rates from the MANR and BURN treatments were 26%and 17%lower,respectively,than the UNCUT treatment over 1 year.The MANR and BURN treatment resulted in soils with 27%and 9%reduction in total phospholipid fatty acids(PLFAs)and 18%and 10%reduction in bacterial PLFAs,respectively,compared with the UNCUT treatment.However,no significant differences existed between slash removal treatments with respect to soil chemical properties,SOC chemical compositions,soil respiration and microbial communities;although PLFA patterns were notably different for the burned plots.Most factors affecting C dynamics and microbial communities were not sensitive to the differences imparted to the ecosystem due to manual slash removal or burning.Our results suggested that low-intensity burning after clear-cutting might have no significant effect on soil C pool and its dynamics compared with manual slash removal in subtropical plantations.
基金This research was financially supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘A vertical-flow constructed wetland(VFCW)was used to treat simulated domestic sewage containing perfluorooctane sulfonate(PFOS).The removal rate of PFOS in the domestic sewage was 93%–98%,through soil adsorption and plant uptake,suggesting that VFCWs can remove PFOS efficiently from wastewater.The removal of PFOS in the VFCW was dependent on soil adsorption and plant uptake;moreover,the percentage of soil adsorption was 61%–89%,and was higher than that of the plants uptake(5%–31%).The absorption capacity of Eichhornia crassipes(E.crassipes)(1186.71 mg/kg)was higher than that of Cyperus alternifolius(C.alternifolius)(162.77 mg/kg)under 10 mg/L PFOS,and the transfer factor of PFOS in E.crassipes and C.alternifolius was 0.04 and 0.58,respectively,indicating that PFOS is not easily translocated to leaves from roots of wetland plants;moreover,uptake of PFOS by E.crassipes was more than that of C.alternifolius because the biomass of E.crassipes was more than that of C.alternifolius and the roots of E.crassipes can take up PFOS directly from wastewater while C.alternifolius needs to do so via its roots in the soil.The concentration of 10 mg/L PFOS had an obvious inhibitory effect on the removal rate of total nitrogen,total phosphorus,chemical oxygen demand,and ammonia nitrogen in the VFCW,which decreased by 15%,10%,10%and 12%,respectively.Dosing with PFOS in the wastewater reduced the bacterial richness but increased the diversity in soil because PFOS stimulated the growth of PFOS-tolerant strains.
基金supported by the National Natural Science Foundation of China(No.31670507)National Key R&D Program of China(No.2019YFC1805803)+1 种基金the National Natural Science Foundation of China(Nos.41907273 and 91951108)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA23010400)。
文摘Polycyclic aromatic hydrocarbons(PAHs)are ubiquitous priority pollutants that cause great damage to the natural environment and health.Average genome size in a community is critical for shedding light on microbiome's functional response to pollution stress within an environment.Here,microcosms under different concentrations were performed to evaluate the selection of PAHs stress on the average genome size in a community.We found the distinct communities of significantly larger genome size with the increase of PAHs concentration gradients in soils,and consistent trends were discovered in soils at different latitudes.The abundance of Proteobacteria and Deinococcus-Thermus with relatively larger genomes increased along with PAHs stress and well adapted to polluted environments.In contrast,the abundance of Patescibacteria with a highly streamlined and smaller genome decreased,implying complex interactions between environmental selection and functional fitness resulted in bacteria with larger genomes becoming more abundant.Moreover,we confirmed the increased capacity for horizontal transfer of degrading genes between communities by showing an increased connection number per node positively related to the nid A gene along the concentration gradients in the co-occurrence network.Our findings suggest PAHs tend to select bacterial taxa with larger genome sizes,with significant consequences for community stability and potential biodegradation strategies.
