Microorganisms respond to various adverse environmental conditions and regulate different physiological functions by secreting and sensing signal molecules through quorum sensing(QS)systems.Phyllosilicates and iron ox...Microorganisms respond to various adverse environmental conditions and regulate different physiological functions by secreting and sensing signal molecules through quorum sensing(QS)systems.Phyllosilicates and iron oxides present in soils and sediments may have substantial impact on bacterial activity and QS due to their unique reactivity and close association with microorganisms.This research explored the effect of goethite,montmorillonite and kaolinite(0.05–2gL^(–1))on the growth and QS of a bacterial model,Chromobacterium violaceum.The results showed that kaolinite and goethite caused cellular damage at low mineral concentrations.The capacity for violacein production and biofilm formation of C.violaceum were inhibited by the minerals in the order of kaolinite>goethite>montmorillonite.The possible underlying mechanisms for QS inhibition by different minerals were investigated.Specifically,kaolinite repressed QS function through downregulation the expression of signal molecules synthesis gene cviI.Goethite and montmorillonite interfered with QS by adsorption of extracellular signal molecules.This work provides a better understanding of the interactions between bacteria and minerals and proposed that the inhibition of QS system is an ignored mechanism for bacterial toxicity by phyllosilicates and iron oxides.展开更多
Biochar is an effective absorbent for remediating heavy metal contaminated soil,but functional optimization is still needed to improve its performance in field application.Here,we characterized the physical structures...Biochar is an effective absorbent for remediating heavy metal contaminated soil,but functional optimization is still needed to improve its performance in field application.Here,we characterized the physical structures and surface chemical properties of raw wood biochar and palm biochar(WB and PB)and the corresponding sulfhydryl-modified biochar(SWB and SPB).Their adsorption capacity for Pb was evaluated by combining thermodynamic and kinetic adsorption at 0.01 mol/L KCl and corresponding model simulation.The results demonstrated successful grafting of sulfhydryl groups onto the biochar,which dramatically reduced the specific surface area(SSA)and pore volume of biochar.The pKa in the surface complexation model(SCM)indicated similar proton affinity between sulfhydryl groups and original functional groups on the biochar.SCM could satisfactorily fit the Pb adsorption behaviors,and model analysis revealed that Pb tended to be adsorbed on low-proton affin-ity sites at low pH,but high-proton affinity sites became dominant in Pb adsorption with increasing pH and adsorbed almost all Pb ions at pH>7.0.Besides,the Pb adsorption density of SWB and SPB was improved by 8.86 and 3.64 folds relative to that of WB and PB,respectively.Over 90% of initially added Pb ions were removed in 1440 and 720 min by raw and sulfhydryl-modified biochar,respectively,indicating that sulfhydryl modification accelerated the Pb adsorption of biochar.These results suggest that site density,SSA and pore structure of biochar play crucial roles in heavy metal adsorption,and sulfhydryl modification may improve the performance of biochar in remediating heavy metal contaminated soil.展开更多
The adsorption and oxidation of arsenite[As(Ⅲ)]by soil components are critical processes that influence its toxicity and mobility.However,the specific mechanisms driving the synergistic interactions among bacteria,so...The adsorption and oxidation of arsenite[As(Ⅲ)]by soil components are critical processes that influence its toxicity and mobility.However,the specific mechanisms driving the synergistic interactions among bacteria,soil minerals,and humic acid(HA)in these processes remain insufficiently understood.This study investigated the effects of goethite and HA association on As(Ⅲ)adsorption-oxidation by the As(Ⅲ)-oxidizing bacterium SY8 using batch incubation experiments and spectroscopic analyses.The results indicated that goethite inhibited the growth of SY8,but its binary and ternary composites with HA and SY8 substantially enhanced the adsorption and oxidation of As(Ⅲ)compared to SY8 alone.This enhancement could be attributed to the generation of hydroxyl radicals(·OH)through Fenton-like reactions that contribute to the enhanced oxidation of As(Ⅲ).The Fenton-like reactions involved interactions between H_(2)O_(2) and goethite,as well as the activation of molecular O_(2) by structural Fe(Ⅱ).Furthermore,the proportion of As(V)associated with the solids was lower than that in the solution,suggesting that As(Ⅲ)oxidation by SY8 was potentially inhibited by As(Ⅲ)adsorption on goethite.Additionally,HA did not affect SY8 growth or its As(Ⅲ)oxidation capability,but slightly enhanced As adsorption on the composites.These findings reveal a complex interplay among microbial,mineral,and organic matter interactions.Understanding these interactions is essential for elucidating soil As biogeochemical processes and developing effective remediation strategies for As-contaminated environments.展开更多
Microbes play a crucial ecological role in soils,but the presence of relic DNA left by previous microorganisms can lead to inaccurate estimations of viable microbial function and diversity.To address this,we proposed ...Microbes play a crucial ecological role in soils,but the presence of relic DNA left by previous microorganisms can lead to inaccurate estimations of viable microbial function and diversity.To address this,we proposed a new method for removing relic DNA in soil using Benzonase endonuclease and compared it with propidium monoazide(PMA)and DNase I,which have been widely applied in viable microbiome studies.Unlike PMA,Benzonase does not require light activation and is suitable for use in opaque media such as soil.Therefore,its efficiency(40%-60%)in removing soil relic DNA was twice that of PMA(0-30%).Moreover,our results showed that Benzonase outperformed DNase I in most soils,probably due to its broader range of operating conditions compared to DNase I.In addition to higher relic DNA removal efficiency,Benzonase exhibited a weak impact on soil viable microbial communities.Subsequently,Benzonase was used to remove relic DNA in natural soils,and the results showed that relic DNA removal led to an approximately 10%reduction in microbial diversity and richness on average.Notably,it caused significant changes in the relative abundance of specific taxa,such as Bacillus and Sphingomonas.These findings reveal disparities between total and viable microbiomes in soils.Our study not only provides a reliable method for soil relic DNA removal but also highlights the necessity of relic DNA removal for viable soil microbiome assessments,laying the methodological foundation for advancing soil microbial ecology research.展开更多
Agricultural ecosystems play a pivotal role in global carbon(C)sequestration efforts.Microbial C use efficiency(CUE)serves as a comprehensive metric that reflects the balance between microbial contributions to the acc...Agricultural ecosystems play a pivotal role in global carbon(C)sequestration efforts.Microbial C use efficiency(CUE)serves as a comprehensive metric that reflects the balance between microbial contributions to the accumulation and decomposition of soil organic C.However,the overall distribution patterns and underlying drivers of microbial CUE at the national scale remain unclear.Herein,data from 209 paired samples from 55 studies were analyzed to assess the distribution patterns and influencing factors of microbial CUE based on enzyme stoichiometry(CUE_(ST))in agricultural ecosystems across China.Results revealed that farmlands exhibited the highest CUE_(ST)value(mean=0.51),exceeding those of grasslands(0.46)and forests(0.44).Contrasting patterns of CUE_(ST)regulation were observed across land-use types,with farmlands showing significant(P<0.001)positive relationships of CUE_(ST)with phosphorus vs.nitrogen(N/P)limitation index,while grasslands and forests demonstrated inverse(P<0.05)relationships of CUE_(ST)with C limitation index.Nutrient stoichiometry emerged as the dominant driver of CUE_(ST),with enzyme ratios and mean annual precipitation playing secondary roles.Moreover,land management practices,including fertilization,grazing,and tillage,as well as land-use transition,significantly influenced microbial CUE_(ST)by potentially altering nutrient availability and soil properties;notably,water addition in grasslands had particularly positive effects.These findings provide a critical foundation for harnessing microbial CUE in agriculture and may inform scalable strategies to enhance soil C sequestration and climate-smart land management.展开更多
基金the National Natural Science Foundation of China(41877029,41961130383)Royal Society-Newton Advanced Fellowship(NAF\R1\191017)+1 种基金the National Key Research Program of China(2016YFD0800206)Wuhan Science and Technology Bureau(2019020701011469).
文摘Microorganisms respond to various adverse environmental conditions and regulate different physiological functions by secreting and sensing signal molecules through quorum sensing(QS)systems.Phyllosilicates and iron oxides present in soils and sediments may have substantial impact on bacterial activity and QS due to their unique reactivity and close association with microorganisms.This research explored the effect of goethite,montmorillonite and kaolinite(0.05–2gL^(–1))on the growth and QS of a bacterial model,Chromobacterium violaceum.The results showed that kaolinite and goethite caused cellular damage at low mineral concentrations.The capacity for violacein production and biofilm formation of C.violaceum were inhibited by the minerals in the order of kaolinite>goethite>montmorillonite.The possible underlying mechanisms for QS inhibition by different minerals were investigated.Specifically,kaolinite repressed QS function through downregulation the expression of signal molecules synthesis gene cviI.Goethite and montmorillonite interfered with QS by adsorption of extracellular signal molecules.This work provides a better understanding of the interactions between bacteria and minerals and proposed that the inhibition of QS system is an ignored mechanism for bacterial toxicity by phyllosilicates and iron oxides.
基金This research was supported by the National Natural Science Foundation of China(Nos.41601231 and 41425006)We are also thankful to Prof.Zuoxiong Liu from the Foreign Language School of HZAU for his help to edit and polish the English language of the manuscript.
文摘Biochar is an effective absorbent for remediating heavy metal contaminated soil,but functional optimization is still needed to improve its performance in field application.Here,we characterized the physical structures and surface chemical properties of raw wood biochar and palm biochar(WB and PB)and the corresponding sulfhydryl-modified biochar(SWB and SPB).Their adsorption capacity for Pb was evaluated by combining thermodynamic and kinetic adsorption at 0.01 mol/L KCl and corresponding model simulation.The results demonstrated successful grafting of sulfhydryl groups onto the biochar,which dramatically reduced the specific surface area(SSA)and pore volume of biochar.The pKa in the surface complexation model(SCM)indicated similar proton affinity between sulfhydryl groups and original functional groups on the biochar.SCM could satisfactorily fit the Pb adsorption behaviors,and model analysis revealed that Pb tended to be adsorbed on low-proton affin-ity sites at low pH,but high-proton affinity sites became dominant in Pb adsorption with increasing pH and adsorbed almost all Pb ions at pH>7.0.Besides,the Pb adsorption density of SWB and SPB was improved by 8.86 and 3.64 folds relative to that of WB and PB,respectively.Over 90% of initially added Pb ions were removed in 1440 and 720 min by raw and sulfhydryl-modified biochar,respectively,indicating that sulfhydryl modification accelerated the Pb adsorption of biochar.These results suggest that site density,SSA and pore structure of biochar play crucial roles in heavy metal adsorption,and sulfhydryl modification may improve the performance of biochar in remediating heavy metal contaminated soil.
基金supported by the National Key Research and Development Program(2020YFC1806803 and 2023YFD1702800)National Natural Science Foundation of China(No.41977021 and 42030709).
文摘The adsorption and oxidation of arsenite[As(Ⅲ)]by soil components are critical processes that influence its toxicity and mobility.However,the specific mechanisms driving the synergistic interactions among bacteria,soil minerals,and humic acid(HA)in these processes remain insufficiently understood.This study investigated the effects of goethite and HA association on As(Ⅲ)adsorption-oxidation by the As(Ⅲ)-oxidizing bacterium SY8 using batch incubation experiments and spectroscopic analyses.The results indicated that goethite inhibited the growth of SY8,but its binary and ternary composites with HA and SY8 substantially enhanced the adsorption and oxidation of As(Ⅲ)compared to SY8 alone.This enhancement could be attributed to the generation of hydroxyl radicals(·OH)through Fenton-like reactions that contribute to the enhanced oxidation of As(Ⅲ).The Fenton-like reactions involved interactions between H_(2)O_(2) and goethite,as well as the activation of molecular O_(2) by structural Fe(Ⅱ).Furthermore,the proportion of As(V)associated with the solids was lower than that in the solution,suggesting that As(Ⅲ)oxidation by SY8 was potentially inhibited by As(Ⅲ)adsorption on goethite.Additionally,HA did not affect SY8 growth or its As(Ⅲ)oxidation capability,but slightly enhanced As adsorption on the composites.These findings reveal a complex interplay among microbial,mineral,and organic matter interactions.Understanding these interactions is essential for elucidating soil As biogeochemical processes and developing effective remediation strategies for As-contaminated environments.
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.32100094 to Y.Wang and 42020104003 to Q.Huang)。
文摘Microbes play a crucial ecological role in soils,but the presence of relic DNA left by previous microorganisms can lead to inaccurate estimations of viable microbial function and diversity.To address this,we proposed a new method for removing relic DNA in soil using Benzonase endonuclease and compared it with propidium monoazide(PMA)and DNase I,which have been widely applied in viable microbiome studies.Unlike PMA,Benzonase does not require light activation and is suitable for use in opaque media such as soil.Therefore,its efficiency(40%-60%)in removing soil relic DNA was twice that of PMA(0-30%).Moreover,our results showed that Benzonase outperformed DNase I in most soils,probably due to its broader range of operating conditions compared to DNase I.In addition to higher relic DNA removal efficiency,Benzonase exhibited a weak impact on soil viable microbial communities.Subsequently,Benzonase was used to remove relic DNA in natural soils,and the results showed that relic DNA removal led to an approximately 10%reduction in microbial diversity and richness on average.Notably,it caused significant changes in the relative abundance of specific taxa,such as Bacillus and Sphingomonas.These findings reveal disparities between total and viable microbiomes in soils.Our study not only provides a reliable method for soil relic DNA removal but also highlights the necessity of relic DNA removal for viable soil microbiome assessments,laying the methodological foundation for advancing soil microbial ecology research.
基金financially supported by the National Natural Science Foundation of China(Nos.42225706,42377297,42407408,42177283)the Fundamental Research Funds for the Central Universities of China(No.2662023PY010)the support from the Postdoctoral Fellowship Program of the China Postdoctoral Science Foundation(No.GZB20230246)。
文摘Agricultural ecosystems play a pivotal role in global carbon(C)sequestration efforts.Microbial C use efficiency(CUE)serves as a comprehensive metric that reflects the balance between microbial contributions to the accumulation and decomposition of soil organic C.However,the overall distribution patterns and underlying drivers of microbial CUE at the national scale remain unclear.Herein,data from 209 paired samples from 55 studies were analyzed to assess the distribution patterns and influencing factors of microbial CUE based on enzyme stoichiometry(CUE_(ST))in agricultural ecosystems across China.Results revealed that farmlands exhibited the highest CUE_(ST)value(mean=0.51),exceeding those of grasslands(0.46)and forests(0.44).Contrasting patterns of CUE_(ST)regulation were observed across land-use types,with farmlands showing significant(P<0.001)positive relationships of CUE_(ST)with phosphorus vs.nitrogen(N/P)limitation index,while grasslands and forests demonstrated inverse(P<0.05)relationships of CUE_(ST)with C limitation index.Nutrient stoichiometry emerged as the dominant driver of CUE_(ST),with enzyme ratios and mean annual precipitation playing secondary roles.Moreover,land management practices,including fertilization,grazing,and tillage,as well as land-use transition,significantly influenced microbial CUE_(ST)by potentially altering nutrient availability and soil properties;notably,water addition in grasslands had particularly positive effects.These findings provide a critical foundation for harnessing microbial CUE in agriculture and may inform scalable strategies to enhance soil C sequestration and climate-smart land management.
