1.Introduction Microbiologically influenced corrosion(MIC)is the destruction of metal materials caused by the activity of microorganisms and the participation of biofilms[1].Global economic costs caused by marine corr...1.Introduction Microbiologically influenced corrosion(MIC)is the destruction of metal materials caused by the activity of microorganisms and the participation of biofilms[1].Global economic costs caused by marine corrosion come to hundreds of billion dollars per year,with approximately 20% of corrosion losses caused by MIC[2].The MIC poses a serious threat to the integrity and safety of assets in the oil and gas industry,water industry,and nuclear waste storage facili-ties[3-5].展开更多
Biochar, carbonaceous material produced from biomass pyrolysis, has been demonstrated to have electron transfer property(associated with redox active groups and multi condensed aromatic moiety), and to be also involve...Biochar, carbonaceous material produced from biomass pyrolysis, has been demonstrated to have electron transfer property(associated with redox active groups and multi condensed aromatic moiety), and to be also involved in biogeochemical redox reactions. In this study, the enhanced removal of Cr(VI) by Shewanella oneidensis MR-1(MR-1) in the presence of biochars with different pyrolysis temperatures(300 to 800 ℃) was investigated to understand how biochar interacts with Cr(VI) reducing bacteria under anaerobic condition. The promotion effects of biochar(as high as 1.07~1.47 fold) were discovered in this process, of which the synergistic effect of BMBC700(ball milled biochar) and BMBC800 with MR-1 was noticeable, in contrast, the synergistic effect of BMBCs(300–600 ℃) with MR-1 was not recognized. The more enhanced removal effect was observed with the increase of BMBC dosage for BMBC700 + MR-1 group. The conductivity and conjugated O-containing functional groups of BMBC700 particles themselves has been proposed to become a dominant factor for the synergistic action with this strain. And, the smallest negative Zeta potential of BMBC700 and BMBC800 is thought to favor decreasing the distance from microbe than other BMBCs. The results are expected to provide some technical considerations and scientific insight for the optimization of bioreduction by useful microbes combining with biochar composites to be newly developed.展开更多
Anthraquinone-2-sulfonate(AQS) was employed in humus substitutes to evaluate the effects and influencing factors of U(VI) reduction by Shewanella oneidensis MR-1(S. oneidensis MR-1) under anaerobic condition. Th...Anthraquinone-2-sulfonate(AQS) was employed in humus substitutes to evaluate the effects and influencing factors of U(VI) reduction by Shewanella oneidensis MR-1(S. oneidensis MR-1) under anaerobic condition. The removal rate of U(VI) at 30 °C reaches 99.0% afterd 96 h with the p H value of 7.0 and AQS concentration of 1.0 mmol/L. The effective concentrations of AQS as the accelerator for U(VI) bioreduction are approximately 0.5-1.0 mmol/L. The bioreduction of U(VI) is inhibited when the concentration of AQS exceeds 2.0 mmol/L. The coexistence of ions, such as Cu2+, Cr6+, Mn2+, shows a remarkable negative effect on the U(VI) reduction, and Zn2+ shows less influence on the process compared with other tested ions. The U(VI) reduction is remarkably inhibited when the concentration of nitrate ion exceeds 1.0 mmol/L. Otherwise, no difference is found when the nitrate ion concentration is less than 0.5 mmol/L. Sulfate ion(5.0 mmol/L) slightly promotes the U(VI) reduction. Zero-valent iron(ZVI) promotes the U(VI) reduction by S. oneidensis, and the reduction rate improves with increasing the amount of ZVI in the range of 0-2.0 g/L. The XPS result indicates that uranium deposits on the cell surface are in U(VI) and U(IV) forms, and the majority of uranium in the solution is stable UO2.展开更多
Programming non-canonical organisms is more attractive due to the prospect of high-value chemical production.Among all,Shewanella oneidensis MR-1 possesses outstanding heme synthesis ability and is well-known for elec...Programming non-canonical organisms is more attractive due to the prospect of high-value chemical production.Among all,Shewanella oneidensis MR-1 possesses outstanding heme synthesis ability and is well-known for electron transfer,thus has high potential in microbial fuel cell and bioremediation.However,heme,as the final product of C4 and C5 pathways,is regulated by heme cluster for the high-value 5-aminolevulinic acid(ALA)for cancer photodynamic therapy,which has never been explored in MR-1.Herein,the heme metabolism in MR-1 was firstly optimized for ALA production.We applied CRISPR interference(CRISPRi)targeted on the genes to fine-tune carbon flux in TCA cycle and redirected the carbon out-flux from heme,leading to a significant change in the amino acid profiles,while downregulation of the essential hemB showed a 2-fold increasing ALA production via the C5 pathway.In contrast,the modular design including of glucokinase,GroELS chaperone,and ALA synthase from Rhodobacter capsulatus enhanced ALA production markedly in the C4 pathway.By integrating gene cluster under dual T7 promoters,we obtained a new strain M::TRG,which significantly improved ALA production by 145-fold.We rewired the metabolic flux of MR-1 through this modular design and successfully produced the high-value ALA compound at the first time.展开更多
The goal of this study is to enhance the efficiency of bacterial extracellular electron transfer (EET) in Shewanella oneidensis MR-1 by enhancing adhesion to the electrode surface. Our results clearly show a major dif...The goal of this study is to enhance the efficiency of bacterial extracellular electron transfer (EET) in Shewanella oneidensis MR-1 by enhancing adhesion to the electrode surface. Our results clearly show a major difference in attachment and behavior of S. oneidensis MR-1 for Ca2+, Pb2+, Cd2+, and Mg2+ compared to the control. The final microbial coverage, as measured by confocal microscopy and cathodic peak charge in cyclic voltammetry (Qpc), increases with increasing metal ion concentrations. We found the cells attached to the electrode increased more with the addition of metal ion concentrations in the following order of metals: Ca2+ > Pb2+ > Cd2+ > Mg2+ compared to the control. The effect of metal ions on metabolism of the bacteria was tested by the riboflavin production and glucose consumption. Metabolic activity mirrored the same order of the activity as the electrochemical results.展开更多
The electrode material is an important aspect for the efficiency and costs in the microbial fuel cells (MFCs). Enhancing of current production and bacteria attachment to the electrode are essential goals for developin...The electrode material is an important aspect for the efficiency and costs in the microbial fuel cells (MFCs). Enhancing of current production and bacteria attachment to the electrode are essential goals for developing the performance of MFCs. In this study, the role of the structural iron present in clays in enhancing the electron transfer of Shewanella oneidensis MR-1 was investigated. Two types of clay containing different amounts of iron situated in the octahedral sites were used to modify ITO (indium tin oxide) electrodes, namely nontronite NAu-1, and montmorillonite (Wyoming) SWy-1. Synthetic montmorillonite SYn-1 which is iron-free clay was used for comparison. The interaction between the bacterial cells and the clays was studied by potential-step chronoamperometry, cyclic voltammetry, confocal microscopy, and scanning electron microscopy (SEM). The obtained results showed that the current densities generated upon ITO electrode modification using the NAu-1 and SWy-1 iron-containing clays were 19 and 3 times higher than that produced using the bare ITO electrode. No current density was obtained when utilizing the synthetic montmorillonite SYn-1 clay. SEM and confocal microscopy observations confirmed the increased coverage percentage of the bacterial cells attached to the clay-modified electrodes compared to the bare ITO.展开更多
基金supported by the National Natural Science Foun-dation of China(Nos.52371071,51971228,and 51771212).
摘要1.Introduction Microbiologically influenced corrosion(MIC)is the destruction of metal materials caused by the activity of microorganisms and the participation of biofilms[1].Global economic costs caused by marine corrosion come to hundreds of billion dollars per year,with approximately 20% of corrosion losses caused by MIC[2].The MIC poses a serious threat to the integrity and safety of assets in the oil and gas industry,water industry,and nuclear waste storage facili-ties[3-5].
基金The study was supported by the Natural Science Foundation of Tianjin(No.20JCZDJC00700)the National Natural Science Foundation of China(Nos.U1806216,41877372)+1 种基金the National Key R&D Program of China(No.2018YFC1802002)111 program,Ministry of Education,China(No.T2017002).
摘要Biochar, carbonaceous material produced from biomass pyrolysis, has been demonstrated to have electron transfer property(associated with redox active groups and multi condensed aromatic moiety), and to be also involved in biogeochemical redox reactions. In this study, the enhanced removal of Cr(VI) by Shewanella oneidensis MR-1(MR-1) in the presence of biochars with different pyrolysis temperatures(300 to 800 ℃) was investigated to understand how biochar interacts with Cr(VI) reducing bacteria under anaerobic condition. The promotion effects of biochar(as high as 1.07~1.47 fold) were discovered in this process, of which the synergistic effect of BMBC700(ball milled biochar) and BMBC800 with MR-1 was noticeable, in contrast, the synergistic effect of BMBCs(300–600 ℃) with MR-1 was not recognized. The more enhanced removal effect was observed with the increase of BMBC dosage for BMBC700 + MR-1 group. The conductivity and conjugated O-containing functional groups of BMBC700 particles themselves has been proposed to become a dominant factor for the synergistic action with this strain. And, the smallest negative Zeta potential of BMBC700 and BMBC800 is thought to favor decreasing the distance from microbe than other BMBCs. The results are expected to provide some technical considerations and scientific insight for the optimization of bioreduction by useful microbes combining with biochar composites to be newly developed.
基金Projects(1117508111475080)supported by the National Natural Science Foundation of China+3 种基金project(13JJ3078)supported by the Natural Science Foundation of Hunan ProvinceChinaProject(14k083)supported by the Innovation Platform Open Fund Project of University in Hunan ProvinceChina
摘要Anthraquinone-2-sulfonate(AQS) was employed in humus substitutes to evaluate the effects and influencing factors of U(VI) reduction by Shewanella oneidensis MR-1(S. oneidensis MR-1) under anaerobic condition. The removal rate of U(VI) at 30 °C reaches 99.0% afterd 96 h with the p H value of 7.0 and AQS concentration of 1.0 mmol/L. The effective concentrations of AQS as the accelerator for U(VI) bioreduction are approximately 0.5-1.0 mmol/L. The bioreduction of U(VI) is inhibited when the concentration of AQS exceeds 2.0 mmol/L. The coexistence of ions, such as Cu2+, Cr6+, Mn2+, shows a remarkable negative effect on the U(VI) reduction, and Zn2+ shows less influence on the process compared with other tested ions. The U(VI) reduction is remarkably inhibited when the concentration of nitrate ion exceeds 1.0 mmol/L. Otherwise, no difference is found when the nitrate ion concentration is less than 0.5 mmol/L. Sulfate ion(5.0 mmol/L) slightly promotes the U(VI) reduction. Zero-valent iron(ZVI) promotes the U(VI) reduction by S. oneidensis, and the reduction rate improves with increasing the amount of ZVI in the range of 0-2.0 g/L. The XPS result indicates that uranium deposits on the cell surface are in U(VI) and U(IV) forms, and the majority of uranium in the solution is stable UO2.
摘要Programming non-canonical organisms is more attractive due to the prospect of high-value chemical production.Among all,Shewanella oneidensis MR-1 possesses outstanding heme synthesis ability and is well-known for electron transfer,thus has high potential in microbial fuel cell and bioremediation.However,heme,as the final product of C4 and C5 pathways,is regulated by heme cluster for the high-value 5-aminolevulinic acid(ALA)for cancer photodynamic therapy,which has never been explored in MR-1.Herein,the heme metabolism in MR-1 was firstly optimized for ALA production.We applied CRISPR interference(CRISPRi)targeted on the genes to fine-tune carbon flux in TCA cycle and redirected the carbon out-flux from heme,leading to a significant change in the amino acid profiles,while downregulation of the essential hemB showed a 2-fold increasing ALA production via the C5 pathway.In contrast,the modular design including of glucokinase,GroELS chaperone,and ALA synthase from Rhodobacter capsulatus enhanced ALA production markedly in the C4 pathway.By integrating gene cluster under dual T7 promoters,we obtained a new strain M::TRG,which significantly improved ALA production by 145-fold.We rewired the metabolic flux of MR-1 through this modular design and successfully produced the high-value ALA compound at the first time.
摘要The goal of this study is to enhance the efficiency of bacterial extracellular electron transfer (EET) in Shewanella oneidensis MR-1 by enhancing adhesion to the electrode surface. Our results clearly show a major difference in attachment and behavior of S. oneidensis MR-1 for Ca2+, Pb2+, Cd2+, and Mg2+ compared to the control. The final microbial coverage, as measured by confocal microscopy and cathodic peak charge in cyclic voltammetry (Qpc), increases with increasing metal ion concentrations. We found the cells attached to the electrode increased more with the addition of metal ion concentrations in the following order of metals: Ca2+ > Pb2+ > Cd2+ > Mg2+ compared to the control. The effect of metal ions on metabolism of the bacteria was tested by the riboflavin production and glucose consumption. Metabolic activity mirrored the same order of the activity as the electrochemical results.
摘要The electrode material is an important aspect for the efficiency and costs in the microbial fuel cells (MFCs). Enhancing of current production and bacteria attachment to the electrode are essential goals for developing the performance of MFCs. In this study, the role of the structural iron present in clays in enhancing the electron transfer of Shewanella oneidensis MR-1 was investigated. Two types of clay containing different amounts of iron situated in the octahedral sites were used to modify ITO (indium tin oxide) electrodes, namely nontronite NAu-1, and montmorillonite (Wyoming) SWy-1. Synthetic montmorillonite SYn-1 which is iron-free clay was used for comparison. The interaction between the bacterial cells and the clays was studied by potential-step chronoamperometry, cyclic voltammetry, confocal microscopy, and scanning electron microscopy (SEM). The obtained results showed that the current densities generated upon ITO electrode modification using the NAu-1 and SWy-1 iron-containing clays were 19 and 3 times higher than that produced using the bare ITO electrode. No current density was obtained when utilizing the synthetic montmorillonite SYn-1 clay. SEM and confocal microscopy observations confirmed the increased coverage percentage of the bacterial cells attached to the clay-modified electrodes compared to the bare ITO.