The application of electron donor and electron shuttle substances has a vital influence on electron transfer,thus may affect the reductive dechlorination of 1,1,1-trichoro-2,2-bis（p-chlorophenyl）ethane（DDT） in ana...The application of electron donor and electron shuttle substances has a vital influence on electron transfer,thus may affect the reductive dechlorination of 1,1,1-trichoro-2,2-bis（p-chlorophenyl）ethane（DDT） in anaerobic reaction systems.To evaluate the roles of citric acid and anthraquinone-2,6-disulfonate（AQDS） in accelerating the reductive dechlorination of DDT in Hydragric Acrisols that contain abundant iron oxide,a batch anaerobic incubation experiment was conducted in a slurry system with four treatments of（1） control,（2） citric acid,（3） AQDS,and（4） citric acid ＋ AQDS.Results showed that DDT residues decreased by 78.93%-92.11% of the initial quantities after 20 days of incubation,and 1,1-dichloro-2,2-bis（4-chlorophenyl）-ethane（DDD） was the dominant metabolite.The application of citric acid accelerated DDT dechlorination slightly in the first 8 days,while the methanogenesis rate increased quickly,and then the acceleration effect improved after the 8th day while the methanogenesis rate decreased.The amendment by AQDS decreased the Eh value of the reaction system and accelerated microbial reduction of Fe（III） oxides to generate Fe（II）,which was an efficient electron donor,thus enhancing the reductive dechlorination rate of DDT.The addition of citric acid ＋ AQDS was most efficient in stimulating DDT dechlorination,but no significant interaction between citric acid and AQDS on DDT dechlorination was observed.The results will be of great significance for developing an efficient in situ remediation strategy for DDT-contaminated sites.展开更多
Microbial oxidation and the mechanism of Sb(Ⅲ)are key governing elements in biogeochemical cycling.A novel Sb oxidizing bacterium,Klebsiella aerogenes HC10,was attracted early and revealed that extracellular metaboli...Microbial oxidation and the mechanism of Sb(Ⅲ)are key governing elements in biogeochemical cycling.A novel Sb oxidizing bacterium,Klebsiella aerogenes HC10,was attracted early and revealed that extracellular metabolites were the main fractions driving Sb oxidation.However,linkages between the extracellular metabolite driven Sb oxidation process and mechanism remain elusive.Here,model phenolic and quinone compounds,i.e.,anthraquinone-2,6-disulfonate(AQDS)and hydroquinone(HYD),representing extracellular oxidants secreted by K.aerogenes HC10,were chosen to further study the Sb(Ⅲ)oxidation mechanism.N_(2)purging and free radical quenching showed that oxygen-induced oxidation accounted for 36.78%of Sb(Ⅲ)in the metabolite reaction system,while hydroxyl free radicals(·OH)accounted for 15.52%.·OH and H_(2)O_(2)are the main driving factors for Sb oxidation.Radical quenching,methanol purification and electron paramagnetic resonance(EPR)analysis revealed that·OH,superoxide radical(O_(2)^(•-))and semiquinone(SQ-•)were reactive intermediates of the phenolic induced oxidation process.Phenolic-induced ROS are one of the main oxidants in metabolites.Cyclic voltammetry(CV)showed that electron transfer of quinone also mediated Sb(Ⅲ)oxidation.Part of Sb(V)was scavenged by the formation of the secondary Sb(V)-bearing mineral mopungite[NaSb(OH)6]in the incubation system.Our study demonstrates the microbial role of oxidation detoxification and mineralization of Sb and provides scientific references for the biochemical remediation of Sb-contaminated soil.展开更多
采用氧化还原介质强化酶电解池(EEC)还原脱氯性能,结果发现,蒽醌-2,6-二磺酸盐(AQDS)、吩嗪-1-甲酰胺(PCN)、氰钴胺(CNB12)和核黄素(RF)均可明显提高EEC系统还原脱氯性能,二氯甲烷(DCM)脱氯率从57%分别提升至81%、72%、86%、84%.考虑到...采用氧化还原介质强化酶电解池(EEC)还原脱氯性能,结果发现,蒽醌-2,6-二磺酸盐(AQDS)、吩嗪-1-甲酰胺(PCN)、氰钴胺(CNB12)和核黄素(RF)均可明显提高EEC系统还原脱氯性能,二氯甲烷(DCM)脱氯率从57%分别提升至81%、72%、86%、84%.考虑到经济成本,选择AQDS作为氧化还原介质进行强化EEC系统还原脱氯性能.在EEC阴极中,AQDS被还原成AH_(2)QDS,可直接与DCM发生氧化还原反应,但不能作为脱卤酶辅酶提高DCM脱氯率.还原性谷胱甘肽(GSH)是脱卤酶的天然辅酶,AQDS加速GSH消耗,且抑制GSH再生.此外,AQDS提升了EEC系统的库仑效率,这意味着更多电子参与了AH_(2)QDS生成.因此,可以推测AQDS是通过直接还原作用强化EEC系统脱氯性能.AQDS-EEC系统的最佳pH值、温度、外加电压分别为7、35℃、-1.2 V vsAg/AgCl.展开更多
The potential of microbial mediated iron plaque reduction, and associated arsenic （As） mobility were examined by iron reducing bacteria enriched from As contaminated paddy soil. To our knowledge, this is the first t...The potential of microbial mediated iron plaque reduction, and associated arsenic （As） mobility were examined by iron reducing bacteria enriched from As contaminated paddy soil. To our knowledge, this is the first time to report the impact of microbial iron plaque reduction on As mobility. Iron reduction occurred during the inoculation of iron reducing enrichment culture in the treatments with iron plaque and ferrihydrite as the electron acceptors, respectively. The Fe（II） concentration with the treatment of anthraquinone-2, 6-disulfonic acid （AQDS） and iron reducing bacteria increased much faster than the control. Arsenic released from iron plaque with the iron reduction, and a significant correlation between Fe（II） and total As in culture was observed. However, compared with control, the increasing rate of As was inhibited by iron reducing bacteria especially in the presence of AQDS. In addition, the concentrations of As（III） and As（V） in abiotic treatments were higher than those in the biotic treatments at day 30. These results indicated that both microbial and chemical reductions of iron plaque caused As release from iron plaque to aqueous phase, however, microbial iron reduction induced the formation of more crystalline iron minerals, leading to As sequestration. In addition, the presence of AQDS in solution can accelerate the iron reduction, the As release from iron plaque and subsequently the As retention in the crystalline iron mineral. Thus, our results suggested that it is possible to remediate As contaminated soils by utilizing iron reducing bacteria and AQDS.展开更多
Uranium-reducing bacteria were immobilized with sodium alginate, anthraquinone-2,6-disulfonate（AQDS）, and carbon nanotubes（CNTs）. The effects of different AQDS-CNTs contents, U（Ⅳ） concentrations, and metal ions...Uranium-reducing bacteria were immobilized with sodium alginate, anthraquinone-2,6-disulfonate（AQDS）, and carbon nanotubes（CNTs）. The effects of different AQDS-CNTs contents, U（Ⅳ） concentrations, and metal ions on U（Ⅳ） reduction by immobilized beads were examined. Over 97.5% U（Ⅵ）（20 mg/L） was removed in 8 hr when the beads were added to 0.7% AQDS-CNTs, which was higher than that without AQDS-CNTs. This result may be attributed to the enhanced electron transfer by AQDS and CNTs. The reduction of U（Ⅵ） occurred at initial U（Ⅵ） concentrations of 10 to 100 mg/L and increased with increasing AQDS-CNT content from 0.1% to 1%. The presence of Fe（Ⅲ）, Cu（Ⅱ） and Mn（Ⅱ）slightly increased U（Ⅵ） reduction, whereas Cr（Ⅵ）, Ni（Ⅱ）, Pb（Ⅱ）, and Zn（Ⅱ） significantly inhibited U（Ⅵ） reduction. After eight successive incubation-washing cycles or 8 hr of retention time（HRT） for 48 hr of continuous operation, the removal efficiency of uranium was above 90% and 92%, respectively. The results indicate that the AQDS-CNT/AL/cell beads are suitable for the treatment of uranium-containing wastewaters.展开更多
Scorodite (FeAsO_(4)·H_(2)O) is a common arsenic-bearing (As-bearing) iron mineral in nearsurface environments that could immobilize or store As in a bound state.In flooded soils,microbe induced Fe(Ⅲ) or As(Ⅴ) ...Scorodite (FeAsO_(4)·H_(2)O) is a common arsenic-bearing (As-bearing) iron mineral in nearsurface environments that could immobilize or store As in a bound state.In flooded soils,microbe induced Fe(Ⅲ) or As(Ⅴ) reduction can increase the mobility and bioavailability of As.Additionally,humic substances can act as electron shuttles to promote this process.The dynamics of As release and diversity of putative As(Ⅴ)-reducing bacteria during scorodite reduction have yet to be investigated in detail in flooded soils.Here,the microbial reductive dissolution of scorodite was conducted in an flooded soil in the presence of anthraquinone-2,6-disulfonate (AQDS).Anaeromyxobacter,Dechloromonas,Geothrix,Geobacter,Ideonella,and Zoogloea were found to be the dominant indigenous bacteria during Fe(Ⅲ) and As(Ⅴ) reduction.AQDS increased the relative abundance of dominant species,but did not change the diversity and microbial community of the systems with scorodite.Among these bacteria,Geobacter exhibited the greatest increase and was the dominant Fe(Ⅲ)-and As(Ⅴ)-reducing bacteria during the incubation with AQDS and scorodite.AQDS promoted both Fe(Ⅲ) and As(Ⅴ) reduction,and over 80%of released As(Ⅴ) was microbially transformed to As(Ⅲ).The increases in the abundance of arrA gene and putative arrA sequences of Geobacter were higher with AQDS than without AQDS.As a result,the addition of AQDS promoted microbial Fe(Ⅲ) and As(Ⅴ) release and reduction from As-bearing iron minerals into the environment.These results contribute to exploration of the transformation of As from As-bearing iron minerals under anaerobic conditions,thus providing insights into the bioremediation of As-contaminated soil.展开更多
Metal-reducing bacteria play a central and important role in the biogeochemical cycle of arsenic(As)and iron(Fe).Research on As/Fe migration from arsenic-containing iron minerals mediated by electronic shuttles is of ...Metal-reducing bacteria play a central and important role in the biogeochemical cycle of arsenic(As)and iron(Fe).Research on As/Fe migration from arsenic-containing iron minerals mediated by electronic shuttles is of significance to groundwater protection and human health.Further,the redox activity and bioavailability of goethite with differing occurrence and distribution of arsenic have not been studied clearly.In this study,the function of electron shuttle AQDS in Fe(III)bioreduction was determined.It was found that acidic conditions were conducive to the growth and reproduction of strain D2201,which was beneficial to the reduction of As(V)/Fe(III).The OD600nm value of the bacteria at pH 6 exceeded twice that at pH 8.Then,three types of goethite,namely pure goethite(Gt),coprecipitated As(V)-goethite(Gt-As),and adsorbed arsenic-goethite(Gt*As),were compared for microbial reduction reactivity.X-ray photoelectron spectroscopy analysis illustrated the proportion of OH-content in Gt-As was much lower than that of Gt and Gt*As,indicating Gt-As carried more surface defects and had higher bioavailability.The Fe(II)content released from AQDS-mediated bioreduction of Gt-As was two-fold higher than that of Gt and Gt*As at pH 7.In addition,pH significantly affected goethite bioreduction efficiency and arsenic migration degree.The dissolved Fe(II)concentration for Gt-As was 0.98,0.133,and 0.139 mM at pH 6,7,and 8,respectively;corresponding to dissolved As(T)content of 3.51,1.48,and 1.31μM within 9 days of culture.This study highlights the significant influence of AQDS and mineral structure on the As/Fe biochemical cycle,which will help further develop the bioremediation of arsenic-contaminated sediments.展开更多
基金supported by the National Natural Science Foundation of China (No.41201314)the Open Fund Project of State Key Laboratory of Soil and Sustainable Agriculture (No.0812201227)
文摘The application of electron donor and electron shuttle substances has a vital influence on electron transfer,thus may affect the reductive dechlorination of 1,1,1-trichoro-2,2-bis（p-chlorophenyl）ethane（DDT） in anaerobic reaction systems.To evaluate the roles of citric acid and anthraquinone-2,6-disulfonate（AQDS） in accelerating the reductive dechlorination of DDT in Hydragric Acrisols that contain abundant iron oxide,a batch anaerobic incubation experiment was conducted in a slurry system with four treatments of（1） control,（2） citric acid,（3） AQDS,and（4） citric acid ＋ AQDS.Results showed that DDT residues decreased by 78.93%-92.11% of the initial quantities after 20 days of incubation,and 1,1-dichloro-2,2-bis（4-chlorophenyl）-ethane（DDD） was the dominant metabolite.The application of citric acid accelerated DDT dechlorination slightly in the first 8 days,while the methanogenesis rate increased quickly,and then the acceleration effect improved after the 8th day while the methanogenesis rate decreased.The amendment by AQDS decreased the Eh value of the reaction system and accelerated microbial reduction of Fe（III） oxides to generate Fe（II）,which was an efficient electron donor,thus enhancing the reductive dechlorination rate of DDT.The addition of citric acid ＋ AQDS was most efficient in stimulating DDT dechlorination,but no significant interaction between citric acid and AQDS on DDT dechlorination was observed.The results will be of great significance for developing an efficient in situ remediation strategy for DDT-contaminated sites.
基金supported by the National Natural Science Foundation of China(No.42267001)the College Young and Middle-aged Teachers’Basic Ability Improvement Project of Guangxi,China(No.2023KY0393).
文摘Microbial oxidation and the mechanism of Sb(Ⅲ)are key governing elements in biogeochemical cycling.A novel Sb oxidizing bacterium,Klebsiella aerogenes HC10,was attracted early and revealed that extracellular metabolites were the main fractions driving Sb oxidation.However,linkages between the extracellular metabolite driven Sb oxidation process and mechanism remain elusive.Here,model phenolic and quinone compounds,i.e.,anthraquinone-2,6-disulfonate(AQDS)and hydroquinone(HYD),representing extracellular oxidants secreted by K.aerogenes HC10,were chosen to further study the Sb(Ⅲ)oxidation mechanism.N_(2)purging and free radical quenching showed that oxygen-induced oxidation accounted for 36.78%of Sb(Ⅲ)in the metabolite reaction system,while hydroxyl free radicals(·OH)accounted for 15.52%.·OH and H_(2)O_(2)are the main driving factors for Sb oxidation.Radical quenching,methanol purification and electron paramagnetic resonance(EPR)analysis revealed that·OH,superoxide radical(O_(2)^(•-))and semiquinone(SQ-•)were reactive intermediates of the phenolic induced oxidation process.Phenolic-induced ROS are one of the main oxidants in metabolites.Cyclic voltammetry(CV)showed that electron transfer of quinone also mediated Sb(Ⅲ)oxidation.Part of Sb(V)was scavenged by the formation of the secondary Sb(V)-bearing mineral mopungite[NaSb(OH)6]in the incubation system.Our study demonstrates the microbial role of oxidation detoxification and mineralization of Sb and provides scientific references for the biochemical remediation of Sb-contaminated soil.
文摘采用氧化还原介质强化酶电解池(EEC)还原脱氯性能,结果发现,蒽醌-2,6-二磺酸盐(AQDS)、吩嗪-1-甲酰胺(PCN)、氰钴胺(CNB12)和核黄素(RF)均可明显提高EEC系统还原脱氯性能,二氯甲烷(DCM)脱氯率从57%分别提升至81%、72%、86%、84%.考虑到经济成本,选择AQDS作为氧化还原介质进行强化EEC系统还原脱氯性能.在EEC阴极中,AQDS被还原成AH_(2)QDS,可直接与DCM发生氧化还原反应,但不能作为脱卤酶辅酶提高DCM脱氯率.还原性谷胱甘肽(GSH)是脱卤酶的天然辅酶,AQDS加速GSH消耗,且抑制GSH再生.此外,AQDS提升了EEC系统的库仑效率,这意味着更多电子参与了AH_(2)QDS生成.因此,可以推测AQDS是通过直接还原作用强化EEC系统脱氯性能.AQDS-EEC系统的最佳pH值、温度、外加电压分别为7、35℃、-1.2 V vsAg/AgCl.
基金supported by the Knowledge Innovation Program of Chinese Academy of Sciences(No. KZCX1-YW-06-03)
文摘The potential of microbial mediated iron plaque reduction, and associated arsenic （As） mobility were examined by iron reducing bacteria enriched from As contaminated paddy soil. To our knowledge, this is the first time to report the impact of microbial iron plaque reduction on As mobility. Iron reduction occurred during the inoculation of iron reducing enrichment culture in the treatments with iron plaque and ferrihydrite as the electron acceptors, respectively. The Fe（II） concentration with the treatment of anthraquinone-2, 6-disulfonic acid （AQDS） and iron reducing bacteria increased much faster than the control. Arsenic released from iron plaque with the iron reduction, and a significant correlation between Fe（II） and total As in culture was observed. However, compared with control, the increasing rate of As was inhibited by iron reducing bacteria especially in the presence of AQDS. In addition, the concentrations of As（III） and As（V） in abiotic treatments were higher than those in the biotic treatments at day 30. These results indicated that both microbial and chemical reductions of iron plaque caused As release from iron plaque to aqueous phase, however, microbial iron reduction induced the formation of more crystalline iron minerals, leading to As sequestration. In addition, the presence of AQDS in solution can accelerate the iron reduction, the As release from iron plaque and subsequently the As retention in the crystalline iron mineral. Thus, our results suggested that it is possible to remediate As contaminated soils by utilizing iron reducing bacteria and AQDS.
基金supported by the China Ocean Mineral Resources Research Program (No. DY125-15-T-08)the National Natural Sciences Foundation of China (Nos. 21176026 21176242)
文摘Uranium-reducing bacteria were immobilized with sodium alginate, anthraquinone-2,6-disulfonate（AQDS）, and carbon nanotubes（CNTs）. The effects of different AQDS-CNTs contents, U（Ⅳ） concentrations, and metal ions on U（Ⅳ） reduction by immobilized beads were examined. Over 97.5% U（Ⅵ）（20 mg/L） was removed in 8 hr when the beads were added to 0.7% AQDS-CNTs, which was higher than that without AQDS-CNTs. This result may be attributed to the enhanced electron transfer by AQDS and CNTs. The reduction of U（Ⅵ） occurred at initial U（Ⅵ） concentrations of 10 to 100 mg/L and increased with increasing AQDS-CNT content from 0.1% to 1%. The presence of Fe（Ⅲ）, Cu（Ⅱ） and Mn（Ⅱ）slightly increased U（Ⅵ） reduction, whereas Cr（Ⅵ）, Ni（Ⅱ）, Pb（Ⅱ）, and Zn（Ⅱ） significantly inhibited U（Ⅵ） reduction. After eight successive incubation-washing cycles or 8 hr of retention time（HRT） for 48 hr of continuous operation, the removal efficiency of uranium was above 90% and 92%, respectively. The results indicate that the AQDS-CNT/AL/cell beads are suitable for the treatment of uranium-containing wastewaters.
基金supported by the National Science Foundation of China(Nos.41977291 and 42177238)the Science and Technology Foundation of Guangdong,China (Nos.2019A1515011482 and2022A1515011093)+2 种基金the Strategic Priority Research Program (No.XDB40020300)the GDAS’Project of Science and Technology Development (Nos.2019GDASYL-0102002-5 and2020GDASYL-20200103077)Light of West China of Chinese Academy of Sciences。
文摘Scorodite (FeAsO_(4)·H_(2)O) is a common arsenic-bearing (As-bearing) iron mineral in nearsurface environments that could immobilize or store As in a bound state.In flooded soils,microbe induced Fe(Ⅲ) or As(Ⅴ) reduction can increase the mobility and bioavailability of As.Additionally,humic substances can act as electron shuttles to promote this process.The dynamics of As release and diversity of putative As(Ⅴ)-reducing bacteria during scorodite reduction have yet to be investigated in detail in flooded soils.Here,the microbial reductive dissolution of scorodite was conducted in an flooded soil in the presence of anthraquinone-2,6-disulfonate (AQDS).Anaeromyxobacter,Dechloromonas,Geothrix,Geobacter,Ideonella,and Zoogloea were found to be the dominant indigenous bacteria during Fe(Ⅲ) and As(Ⅴ) reduction.AQDS increased the relative abundance of dominant species,but did not change the diversity and microbial community of the systems with scorodite.Among these bacteria,Geobacter exhibited the greatest increase and was the dominant Fe(Ⅲ)-and As(Ⅴ)-reducing bacteria during the incubation with AQDS and scorodite.AQDS promoted both Fe(Ⅲ) and As(Ⅴ) reduction,and over 80%of released As(Ⅴ) was microbially transformed to As(Ⅲ).The increases in the abundance of arrA gene and putative arrA sequences of Geobacter were higher with AQDS than without AQDS.As a result,the addition of AQDS promoted microbial Fe(Ⅲ) and As(Ⅴ) release and reduction from As-bearing iron minerals into the environment.These results contribute to exploration of the transformation of As from As-bearing iron minerals under anaerobic conditions,thus providing insights into the bioremediation of As-contaminated soil.
基金the National Natural Science Foundation of China[grant numbers 41572230,41172219]the Grant for Innovative Research Groups of the National Natural Science Foundation of China[grant number 41521001].
文摘Metal-reducing bacteria play a central and important role in the biogeochemical cycle of arsenic(As)and iron(Fe).Research on As/Fe migration from arsenic-containing iron minerals mediated by electronic shuttles is of significance to groundwater protection and human health.Further,the redox activity and bioavailability of goethite with differing occurrence and distribution of arsenic have not been studied clearly.In this study,the function of electron shuttle AQDS in Fe(III)bioreduction was determined.It was found that acidic conditions were conducive to the growth and reproduction of strain D2201,which was beneficial to the reduction of As(V)/Fe(III).The OD600nm value of the bacteria at pH 6 exceeded twice that at pH 8.Then,three types of goethite,namely pure goethite(Gt),coprecipitated As(V)-goethite(Gt-As),and adsorbed arsenic-goethite(Gt*As),were compared for microbial reduction reactivity.X-ray photoelectron spectroscopy analysis illustrated the proportion of OH-content in Gt-As was much lower than that of Gt and Gt*As,indicating Gt-As carried more surface defects and had higher bioavailability.The Fe(II)content released from AQDS-mediated bioreduction of Gt-As was two-fold higher than that of Gt and Gt*As at pH 7.In addition,pH significantly affected goethite bioreduction efficiency and arsenic migration degree.The dissolved Fe(II)concentration for Gt-As was 0.98,0.133,and 0.139 mM at pH 6,7,and 8,respectively;corresponding to dissolved As(T)content of 3.51,1.48,and 1.31μM within 9 days of culture.This study highlights the significant influence of AQDS and mineral structure on the As/Fe biochemical cycle,which will help further develop the bioremediation of arsenic-contaminated sediments.
