A large number of reaction systems are composed of hydrophobic interfaces and microorganisms in natural environment.However,it is not clear how microorganisms adjust their breathing patterns and respond to hydrophobic...A large number of reaction systems are composed of hydrophobic interfaces and microorganisms in natural environment.However,it is not clear how microorganisms adjust their breathing patterns and respond to hydrophobic interfaces.Here,Shewanella oneidensis MR-1 was used to reduce ferrihydrite of a hydrophobic surface.Through Fe(II)kinetic analysis,it was found that the reduction rate of hydrophobic ferrihydrite was 1.8 times that of hydrophilic one.The hydrophobic surface of the mineral hinders the way the electroactive microorganism uses the water-soluble electron mediator riboflavin for indirect electron transfer and promotes MR-1 to produce more liposoluble quinones.Ubiquinone can mediate electron transfer at the hydrophobic interface.Ubiquinone-30(UQ-6)increases the reduction rate of hydrophobic ferrihydrite from 38.5±4.4 to 52.2±0.8 mM$h1.Based on the above experimental results,we propose that liposoluble electron mediator ubiquinone can act on the extracellular hydrophobic surface,proving that the metabolism of hydrophobic minerals is related to endogenous liposoluble quinones.Hydrophobic modification of minerals encourages electroactive microorganisms to adopt differentiated respiratory pathways.This finding helps in understanding the electron transfer behavior of the microbes at the hydrophobic interface and provides new ideas for the study of hydrophobic reactions that may occur in systems,such as soil and sediment.展开更多
Vivianite is often found in reducing environments rich in iron and phosphorus from organic debris degradation or phosphorus mineral dissolution. The formation of vivianite is essential to the geochemical cycling of ph...Vivianite is often found in reducing environments rich in iron and phosphorus from organic debris degradation or phosphorus mineral dissolution. The formation of vivianite is essential to the geochemical cycling of phosphorus and iron elements in natural environments. In this study, extracellular polymeric substances(EPS) were selected as the source of phosphorus. Microcosm experiments were conducted to test the evolution of mineralogy during the reduction of polyferric sulfate flocs(PFS) by Shewanella oneidensis MR-1(S. oneidensis MR-1) at EPS concentrations of 0, 0.03, and 0.3 g/L. Vivianite was found to be the secondary mineral in EPS treatment when there was no phosphate in the media. The EPS DNA served as the phosphorus source and DNA-supplied phosphate could induce the formation of vivianite.EPS impedes PFS aggregation, contains redox proteins and stores electron shuttle, and thus greatly promotes the formation of minerals and enhances the reduction of Fe(Ⅲ). At EPS concentration of 0, 0.03, and 0.3 g/L, the produced HCl-extractable Fe(Ⅱ) was 107.9, 111.0,and 115.2 mg/L, respectively. However, when the microcosms remained unstirred, vivianite can be formed without the addition of EPS. In unstirred systems, the EPS secreted by S. oneidensis MR-1 could agglomerate at some areas, resulting in the formation of vivianite in the proximity of microbial cells. It was found that vivianite can be generated biogenetically by S. oneidensis MR-1 strain and EPS may play a key role in iron reduction and concentrating phosphorus in the oligotrophic ecosystems where quiescent conditions prevail.展开更多
The capability of preparing three-dimensional(3D)printable living inks provides a unique way to harness the activity of microbes and use them in functional devices.Here we demonstrate the incorporation of the living b...The capability of preparing three-dimensional(3D)printable living inks provides a unique way to harness the activity of microbes and use them in functional devices.Here we demonstrate the incorporation of the living bacteria Shewanella Oneidensis MR-1(S.Oneidensis MR-1)directly into an ink used for creating 3D printed structures.Significantly,S.Oneidensis MR-1 survives the 3D printing process by showing prominent activity in degrading the methyl orange azo dye.Through the addition of carbon black to this ink,we further demonstrate the direct printing of a living microbial fuel cell(MFC)anode.To our knowledge,this is the first report on implementing 3D printed bacteria structure as a living electrode for an MFC system.The capability of printing living and functional 3D bacterial structure could open up new possibilities in design and fabrication of microbial devices as well as fundamental research on the interaction between different bacterial strains,electrode materials,and surrounding environments.展开更多
基金This study was supported by grants from the National Key R&D Program of China(2018YFC1800502)the National Natural Science Foundation of China(nos.42021005 and 22025603)the FJIRSM&IUE Joint Research Fund(RHZX-2018-006).
文摘A large number of reaction systems are composed of hydrophobic interfaces and microorganisms in natural environment.However,it is not clear how microorganisms adjust their breathing patterns and respond to hydrophobic interfaces.Here,Shewanella oneidensis MR-1 was used to reduce ferrihydrite of a hydrophobic surface.Through Fe(II)kinetic analysis,it was found that the reduction rate of hydrophobic ferrihydrite was 1.8 times that of hydrophilic one.The hydrophobic surface of the mineral hinders the way the electroactive microorganism uses the water-soluble electron mediator riboflavin for indirect electron transfer and promotes MR-1 to produce more liposoluble quinones.Ubiquinone can mediate electron transfer at the hydrophobic interface.Ubiquinone-30(UQ-6)increases the reduction rate of hydrophobic ferrihydrite from 38.5±4.4 to 52.2±0.8 mM$h1.Based on the above experimental results,we propose that liposoluble electron mediator ubiquinone can act on the extracellular hydrophobic surface,proving that the metabolism of hydrophobic minerals is related to endogenous liposoluble quinones.Hydrophobic modification of minerals encourages electroactive microorganisms to adopt differentiated respiratory pathways.This finding helps in understanding the electron transfer behavior of the microbes at the hydrophobic interface and provides new ideas for the study of hydrophobic reactions that may occur in systems,such as soil and sediment.
基金supported by the National Natural Science Foundation of China (No. 41673090)the Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control (No. 2017B030301012)the Local Innovation and Entrepreneurship Team Project of Guangdong Special Support Program (No. 2019BT02L218)。
文摘Vivianite is often found in reducing environments rich in iron and phosphorus from organic debris degradation or phosphorus mineral dissolution. The formation of vivianite is essential to the geochemical cycling of phosphorus and iron elements in natural environments. In this study, extracellular polymeric substances(EPS) were selected as the source of phosphorus. Microcosm experiments were conducted to test the evolution of mineralogy during the reduction of polyferric sulfate flocs(PFS) by Shewanella oneidensis MR-1(S. oneidensis MR-1) at EPS concentrations of 0, 0.03, and 0.3 g/L. Vivianite was found to be the secondary mineral in EPS treatment when there was no phosphate in the media. The EPS DNA served as the phosphorus source and DNA-supplied phosphate could induce the formation of vivianite.EPS impedes PFS aggregation, contains redox proteins and stores electron shuttle, and thus greatly promotes the formation of minerals and enhances the reduction of Fe(Ⅲ). At EPS concentration of 0, 0.03, and 0.3 g/L, the produced HCl-extractable Fe(Ⅱ) was 107.9, 111.0,and 115.2 mg/L, respectively. However, when the microcosms remained unstirred, vivianite can be formed without the addition of EPS. In unstirred systems, the EPS secreted by S. oneidensis MR-1 could agglomerate at some areas, resulting in the formation of vivianite in the proximity of microbial cells. It was found that vivianite can be generated biogenetically by S. oneidensis MR-1 strain and EPS may play a key role in iron reduction and concentrating phosphorus in the oligotrophic ecosystems where quiescent conditions prevail.
文摘The capability of preparing three-dimensional(3D)printable living inks provides a unique way to harness the activity of microbes and use them in functional devices.Here we demonstrate the incorporation of the living bacteria Shewanella Oneidensis MR-1(S.Oneidensis MR-1)directly into an ink used for creating 3D printed structures.Significantly,S.Oneidensis MR-1 survives the 3D printing process by showing prominent activity in degrading the methyl orange azo dye.Through the addition of carbon black to this ink,we further demonstrate the direct printing of a living microbial fuel cell(MFC)anode.To our knowledge,this is the first report on implementing 3D printed bacteria structure as a living electrode for an MFC system.The capability of printing living and functional 3D bacterial structure could open up new possibilities in design and fabrication of microbial devices as well as fundamental research on the interaction between different bacterial strains,electrode materials,and surrounding environments.
