Journal of Environmental Sciences
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2018
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IF 3.12
Zheng Chen,Yaxian Zhang,Qingliu Luo,Liuying Wang,Shurui Liu,Yajuan Peng,Haitao Wang,Liang Shen,Qingbiao Li,Yuanpeng Wang
Microbially mediated bioreduction of iron oxyhydroxide plays an important role in the biogeochemical cycle of iron. Geobacter sulfurreducens is a representative dissimilatory iron-reducing bacterium that assembles electrically conductive pili and cytochromes . The impact of supplementation with γ-Fe 2 O 3 nanoparticles (NPs) (0.2 and 0.6 g) on the G. sulfurreducens -mediated reduction of ferrihydrite was investigated. In the overall performance of microbial ferrihydrite reduction mediated by γ-Fe 2 O 3 NPs, stronger reduction was observed in the presence of direct contact with γ-Fe 2 O 3 NPs than with indirect contact. Compared to the production of Fe(II) derived from biotic modification with ferrihydrite alone, increases greater than 1.6- and 1.4-fold in the production of Fe(II) were detected in the biotic modifications in which direct contact with 0.2 g and 0.6 g γ-Fe 2 O 3 NPs, respectively, occurred. X-ray diffraction analysis indicated that magnetite was a unique representative iron mineral in ferrihydrite when active G. sulfurreducens cells were in direct contact with γ-Fe 2 O 3 NPs. Because of the sorption of biogenic Fe(II) onto γ-Fe 2 O 3 NPs instead of ferrihydrite, the addition of γ-Fe 2 O 3 NPs could also contribute to increased duration of ferrihydrite reduction by preventing ferrihydrite surface passivation. Additionally, electron microscopy analysis confirmed that the direct addition of γ-Fe 2 O 3 NPs stimulated the electrically conductive pili and cytochromes to stretch, facilitating long-range electron transfer between the cells and ferrihydrite. The obtained findings provide a more comprehensive understanding of the effects of iron oxide NPs on soil biogeochemistry .
研究领域:
微生物学
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环境科学
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PubMed
高影响因子
BIOELECTROCHEMISTRY
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2020
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IF 4.722
Bo Zhang,Hao-Yi Cheng,Aijie Wang
Dissimilatory metal-reducing bacteria (DMRB) have a variety of c-type cytochromes (OM c-cyts) intercalated in their outer membrane, and this structure serves as the physiological basis for DMRB to carry out the extracellular electron transfer processes. Using Geobacter sulfurreducens as a model DMRB, we demonstrated that visible-light illumination could alter the electronic state of OM c-cyts from the ground state to the excited state in vivo . The existence of excited-state OM c-cyts in vivo was confirmed by spectroscopy. More importantly, excited-state OM c-cyts had a more negative potential compared to their ground-state counterparts, conferring DMRB with an extra pathway to transfer electrons to semi-conductive electron acceptors. To demonstrate this, using a TiO 2 -coated electrode as an electron acceptor, we showed that G. sulfurreducens could directly utilise the conduction band of TiO 2 as an electron acceptor under visible-light illumination (λ > 420 nm) without causing TiO 2 charge separation. When G. sulfurreducens was subject to visible-light illumination, the rate of extracellular electron transfer (EET) to TiO 2 accelerated by over 8-fold compared to that observed under dark conditions. Results of additional electrochemical tests provided complementary evidence to support that G. sulfurreducens utilised excited-state OM c-cyts to enhance EET to TiO 2 .
研究领域:
微生物学
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环境科学
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高影响因子
Journal of Environmental Chemical Engineering
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2024
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IF 7.4
Jinyang Chen,Juanli Wu,Ping Liu,Li Gan,Zuliang Chen
Efficient removal and recovery of heavy metals (HMs) from acid mine drainage (AMD) is crucial for both protecting mine ecosystems and reclaiming valuable HMs resources. In this study, biohybrid with ferrous sulfide nanoparticles ( n FeS@GS) were biosynthesized via Geobacter sulfurreducens (GS) and employed for the removal and recovery of HMs from AMD. Initially, n FeS@GS were successfully synthesized as confirmed by TEM and exhibited high efficiencies in removing Cu 2+ and Pb 2+ in solution, respectively. This occurred because bio- n FeS and GS cells synergistically enhanced the removal of Cu 2+ and Pb 2+ . What is more, the removal efficiencies of various HMs from real AMD using n FeS@GS remained high, with documented rates of 87.9 % for Cu 2+ , 96.2 % for Pb 2+ , 95.1 % for Cd 2+ , 81.4 % for Ni 2+ , 80.9 % for Mn 2+ , and 91.9 % for Zn 2+ . Subsequent characterization of the removal function through 3D-EEM, Bio-TEM, XRD, FTIR and XPS analyses revealed substantial organic capping agents derived from GS adhering to the bio- n FeS, forming surface complexes with Cu 2+ and Pb 2+ , and Cu 2+ was reduced to Cu + /Cu 0 . Zeta potential measurements, adsorption kinetics and reduction kinetics supported that the removal mechanism involved electrostatic interactions, surface complexation, ion exchange and reduction. Finally, n FeS@GS desorption rates of HMs exceeded 90.7 %, highlighting the efficacy of n FeS@GS for recovering HMs from AMD. These findings provide valuable and practical insights into the removal and recovery of HMs from AMD using biomaterials synthesized from microorganisms.
研究领域:
环境科学
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微生物学
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高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2022
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IF 14.224
Xiaofeng Yi,Shurui Liu,Mingyu Luo,Qingbiao Li,Yuanpeng Wang
Microbe-photocatalyst biohybrids, integrating the optimal attributes of whole-cell catalysts and nanometer photocatalysts, have emerged as a promising strategy for environment-associated applications. However, few such biohybrids have been tested for complex pollution systems. Herein, we constructed an outer membrane photosensitized Geobacter sulfurreducens ( G. sulfurreducens )-CdS biohybrid, which enabled to generate stronger photocurrent in response to irradiation and meanwhile achieved an significant promotion for the redox transformation of Cr(VI) and tetracycline compared with that of bare G. sulfurreducens or CdS counterparts. Further analysis revealed that the outer membrane played a significant role in photoelectron transfer. Differential pulse voltammetry (DPV) tests demonstrated that CdS enhanced the catalytic activity of C-type cytochromes on the outer membrane under irradiation, resulting in the increase of electron-hole pairs separation efficiency. The possible degradation pathway of tetracycline was proposed based on determined intermediates, whose toxicities were well evaluated. Importantly, the toxicity of the final detected intermediates was apparently decreased. Overall, this work aims to explore the working mechanisms of the novel G. sulfurreducens -CdS biohybrid system and opens up a new avenue to purifying combined wastewater by microbe-photocatalyst biohybrids.
研究领域:
环境科学
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微生物学
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高影响因子
BIOTECHNOLOGY AND BIOENGINEERING
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2023
·Vol. 120
·期 5
·1346-1356
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IF 3.8
Jia-Qi Liu,Xin Ma,Dong-Feng Liu,Chuan-Wang Yang,Dao-Bo Li,Di Min,Han-Qing Yu
Dissimilatory metal-reducing bacteria (DMRB) can transfer electrons to extracellular insoluble electron acceptors and play important roles in geochemical cycling, biocorrosion, environmental remediation, and bioenergy generation. c -type cytochromes ( c -Cyts) are synthesized by DMRB and usually transported to the cell surface to form modularized electron transport conduits through protein assembly, while some of them are released as extracellularly free-moving electron carriers in growth to promote electron transport. However, the type of these released c -Cyts, the timing of their release, and the functions they perform have not been unrevealed yet. In this work, after characterizing the types of c -Cyts released by Geobacter sulfurreducens under a variety of cultivation conditions, we found that these c -Cyts accumulated up to micromolar concentrations in the surrounding medium and conserved their chemical activities. Further studies demonstrated that the presence of c -Cyts accelerated the process of microbial extracellular electron transfer and mediated long-distance electron transfer. In particular, the presence of c -Cyts promoted the microbial respiration and affected the physiological state of the microbial community. In addition, c -Cyts were observed to be adsorbed on the surface of insoluble electron acceptors and modify electron acceptors. These results reveal the overlooked multiple roles of the released c -Cyts in acting as public goods, delivering electrons, modifying electron acceptors, and even regulating bacterial community structure in natural and artificial environments.
研究领域:
微生物学
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环境科学
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生物化学
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高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2024
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IF 12.2
Fang Fang,Lingyun Ding,Yaoyu Zhang,Xuejiao Qiao,Lu Qian,Ruqian Wei,Hanchun Chen,Haodong Ji,Bin Pi,Ming Hung Wong,Huchun Tao,Nan Xu,Lijuan Zhang
There has been a serious health and environmental concern in conversion of inorganic mercury (Hg) to the neurotoxin, methylmercury (MeHg) by anaerobic microbes, while very little is known about the potential role of vitamin B9 (VB9) regulator in the biochemical generation of MeHg. This study innovatively investigated bacterial Hg methylation by Geobacter sulfurreducens PCA in the presence of VB9 under two existing scenarios. In the low-complexing scenario, the bacterial MeHg yield reached 68 % higher than that without VB9 within 72 h, which was attributed to free VB9-protected PCA cells relieving oxidative stress, as manifested by the increased expression of Hg methylation gene ( hgcAB cluster by 19–48 %). The high-complexing scenario emphasized the intracellular Hg accumulation (38–45 %) after 12 h, as indicated by the increased expression of outer membrane protein-related and mercuric reductase-encoding genes, indicating the inefficient bioavailability of Hg due to a gradual shift from Hg reduction toward Hg 0 re-oxidation controlled by competitive ligand exchange. These results suggested that VB9 application significantly raised the potential for bacterial Hg methylation and cellular accumulation, thus proposing insights into the biochemical behaviors of hazardous Hg in farming environments where vulnerable organisms are more possibly co-exposed to higher levels of Hg and VB9.
研究领域:
环境科学
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微生物学
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毒理学
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高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
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2025
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IF 11.3
Wei Yang,Xianyue Jing,Shuyao Lai,Hui Wang,Jun Wang,Xing Liu,Shungui Zhou
Biological nitrogen fixation (BNF) represents a sustainable alternative to the capital- and energy-intensive Haber–Bosch process, which dominates industrial fertilizer production but contributes significantly to global carbon emissions. While Geobacter sulfurreducens has been identified as a promising diazotroph, its BNF efficiency remains untapped. Here, we engineered G. sulfurreducens by deleting the ammonium transporter gene amtB (strain ΔamtB), achieving a record-high BNF rate of 20.57 ± 0.87 mg N L–1 day–1, approximately twice that of the wild-type strain and exceeding those of all reported free-living diazotrophs and synthetic catalysts for ambient nitrogen fixation. 15N isotope labeling and nitrogenase activity assays confirmed enhanced fixation, whereas biofertilizer trials demonstrated the ability of ΔamtB as a biofertilizer to support Arabidopsis thaliana growth. Mechanistic studies revealed that amtB deletion (1) amplified cellular nitrogen assimilation, (2) alleviated ammonium-mediated suppression of nitrogenase activity, and (3) disrupted energy-intensive futile ammonium cycling, conserving cell energy. This study establishes ΔamtB as a scalable BNF platform for sustainable agriculture, offering a viable pathway to decarbonize fertilizer production.
研究领域:
微生物学
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生物技术
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合成生物学
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农业科学
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环境科学
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分子生物学
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PubMed
高影响因子
Frontiers in Microbiology
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2026
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IF 5.8
Fanchao Meng,Ulf Skyllberg,Yangyang Li,Shusaku Hayama,Erik Björn,Yu Song
Mercury (Hg) is a global environmental concern due to its microbial conversion to methylmercury (MeHg), a potent neurotoxin that bioaccumulates in food webs and poses risks to ecosystems and human health. Thiol functional groups (RSH) play an important role in controlling Hg(II) speciation and bio-uptake in methylating bacteria, yet the spatial distribution and density of these thiols within cells remain largely unknown. We isolated subcellular fractions of the Hg methylating bacterium Geobacter sulfurreducens in the exponential growth phase, and used Hg L III -edge EXAFS (Extended X-ray Absorption Fine Structure) to quantify thiols in the extracellular medium, inner and outer membranes, periplasm and cytoplasm. The whole-cell thiol content was determined to be 1.3 × 10 −10 μmol cell −1 . The inner membrane contributed 7.1 × 10 −11 (53%), the outer membrane 1.2 × 10 −11 (9%), the periplasm 3.6 × 10 −11 (27%) and the cytoplasm 1.5 × 10 −11 μmol cell −1 (11%). The extracellular fraction contributed an additional 5.7 × 10 −11 μmol cell −1 , corresponding to 30% of the thiols of the cell culture. Local thiol density (thiols normalized to TOC in individual compartment, RSH/TOC, μmol g −1 C) was 36, 450, 140, 600 and 29 μmol g −1 C in the cytoplasm, inner membrane, periplasm, outer membrane and extracellular fractions, respectively. EXAFS analyses demonstrate Hg-thiolate coordination across all compartments, with Hg-O/N bonding and elemental Hg 0 formed at higher Hg loadings. In the periplasm, Hg-disulfide and traces of β -HgS were detected. The high thiol density at the membranes, relative to other compartments, may imply they have an important role in the retention and internalization of Hg(II). Periplasmic thiols may modulate Hg(II) transfer between membranes, and cytoplasmic thiols may regulate the intracellular availability of Hg(II) for methylation. This work provides the first compartment-resolved quantification of thiol abundances and densities in a model Hg-methylating bacterium at subcellular level, offering a mechanistic framework for understanding the speciation, bioavailability, and subcellular transformation of Hg(II) with relevance for other soft metals (e.g., Cd, Pb, Zn, Ag, and Cu).
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高影响因子
JOURNAL OF PROTEOME RESEARCH
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2019
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IF 3.78
Zhenhua Shi
The Geobacter species evolved respiratory versatility to utilize a wide range of terminal electron acceptors. To explore this adaptive mechanism, Fe(III) citrate, hydrous ferric oxide, and fumarate were selected as electron acceptors, and the methylome and metabolome of Geobacter sulfurreducens PCA grown on each electron acceptor were investigated via third-generation, single-molecule real-time DNA sequencing and gas chromatography/time-of-flight mass spectrometry-based metabolomics, respectively. Results showed that the patterns of 4-methylcytosine (m4C) and 6-methyladenine (m6A) modification, the concentrations of fatty acids (e.g., caprylic acid, capric acid, and squalene), and the activity of antioxidant enzymes (e.g., superoxide dismutase, catalase, and glutathione reductase) were all varied in different electron acceptor cultures. Moreover, genes (e.g., GSU0466 and GSU1467) with low expression levels generally had high methylation levels. These findings suggest that m4C and m6A modifications, fatty acids, and antioxidant enzymes all play a role in the adaptation of G. sulfurreducens to diverse electron acceptors, and DNA methylation may be involved in the adaptation mainly via gene expression regulation.
研究领域:
微生物学
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分子生物学
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环境科学
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PubMed
高影响因子
Journal of Environmental Sciences
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2025
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IF 6.3
Yifan Cui,Xiaoyan Zhang,Peijie Yang,Yanwei Liu,Maoyong Song,Yingying Guo,Wentao Jiao,Yongguang Yin,Yong Cai,Guibin Jiang
Fe reducing bacteria (FRB), through extracellular electron transfer (EET) pathway, can reduce Fe(III) nanoparticles, thereby affecting the migration, transformation, and degradation of pollutants. However, the interaction of Fe(III) nanoparticles with the most commonly identified FRB, Geobacter sulfurreducens PCA, remains poorly understood. Herein, we demonstrated that the synergistic role of outer membrane proteins and periplasmic proteins in the EET process for α-Fe 2 O 3 , Fe 3 O 4 , and β -FeOOH nanoparticles by construction of multiple gene knockout strain. oxpG (involved in the type II secretion system) and omcST (outer membrane c-type cytochrome) mediated pathways accounted for approximately 67 % of the total reduction of α-Fe 2 O 3 nanoparticles. The residual reduction of α-Fe 2 O 3 nanoparticles in ∆ oxpG - omcST strain was likely caused by redox-active substances in cell supernatant. Conversely, the reduction of dissolved Fe(III) was almost unaffected in ∆ oxpG - omcST strain at the same concentration. However, at high dissolved Fe(III) concentration, the reduction significantly decreased due to the formation of Fe(III) nanoparticles, suggesting that this EET process is specific to Fe(III) nanoparticles. Overall, our study provided a more comprehensive understanding for the EET pathways between G. sulfurreducens PCA and different Fe(III) species, enriching our knowledge on the role of microorganisms in iron biogeochemical cycles and remediation strategies of pollutants.
研究领域:
微生物学
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环境科学
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PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2021
·
IF 10.588
Xiaofeng Yi,Shenhua Huang,Lu Chang,Zhaoshou Wang,Yuanpeng Wang
The redistribution process of arsenate (As(V)) and the variation in As(V) content in different locations must be clarified to ensure low mobility of As(V) during microbial ferrihydrite reduction. In this study, we investigated As(V) immobilization and redistribution processes when ferrihydrite was incubated with Geobacter sulfurreducens in the presence of titanium dioxide (TiO 2 ) nanoparticles . Our study results showed that, As(V) in the aqueous phase and ferrihydrite were redistributed on light minerals (goethite), heavy minerals (ferrihydrite and magnetite), and extracellular polymeric substances (EPS) induced by G. sulfurreducens during ferrihydrite reduction. Interestingly, we found that As(V) in the form of arsenate ion (AsO 4 3- ) was adsorbed by the functional groups of the EPS, while the formed Fe II 3 (As V O 4 ) 2 was wrapped in the network structure of EPS. Moreover, the addition of TiO 2 nanoparticles did not promote but delayed the entire ferrihydrite reduction, As(V) immobilization and redistribution processes. Furthermore, changes in the aqueous arsenic and iron concentrations are closely related to the formation time of secondary minerals. Our study findings provide new insights into the As(V) immobilization process mediated by G. sulfurreducens under anaerobic conditions .
研究领域:
环境科学
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微生物学
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高影响因子
危险品化学品经营许可证（带存储）