BIOCHEMICAL ENGINEERING JOURNAL
·
2016
·
IF 2.463
Shan-Wei Li,Raymond J. Zeng,Guo-Ping Sheng
Shewanella oneidensis MR-1, a model electroactive bacterium, can oxidize a variety of fermentative organics and utilize an electrode as an electron acceptor for anaerobic respiration. Chitin as the main component of food wastes (shrimp and crab shells) is hardly degraded for bioenergy generation. This study demonstrated that S. oneidensis MR-1 could degrade chitin in microbial fuel cell (MFC). The metabolites during chitin degradation in MFC were succinate, lactate, acetate, formate, and ethanol. Their concentrations produced in MFC were higher than those in the fermentation system, as well as additional electricity could be recovered in MFC. Furthermore, the degradation of GlcNAc (the intermediate of chitin hydrolysis) by S. oneidensis MR-1 was faster than chitin in MFC and fermentation systems. Moreover, the mechanism of enhanced chitin degradation in MFC was speculated. This work might provide a new insight for biomass treatment and energy recovery by S. oneidensis MR-1 in MFC.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2020
·Vol. 27
·期 14
·16745-16753
·
IF 3.056
Yu Cheng,Zhang Yi,Fang Yu,Tan Yujie,Dai Ke,Liu Shilin,Huang Qiaoyun
Shewanella oneidensis MR-1 (MR-1)-impregnated alginate capsules with 3D porous structure were prepared through cation crossing-linking and was used for the Cr(VI) reduction and removal. After being encapsulated by alginate, the endurance of the MR-1 was largely enhanced under conditions of high Cr(VI) concentrations (up to 4 mM) and low pH (pH 5). The Cr(VI) reduction over the MR-1-impregnated alginate capsules could be fitted by pseudo first-order kinetic model. With the Cr(VI) initial concentration increasing from 1 to 4 mM, the first-order rate constant for the encapsulated MR-1 ( k capsules ) and free cells ( k cells ) fell by 26.3% and 82.4%, respectively. At pH 5, the k capsules value was 0.19 h − 1 , which was about 3.7 times higher than k cells . Moreover, the encapsulated MR-1 held 90.5% of the Cr(VI) reduction ability after 15 days of resting time, while the free MR-1 held 19.7%. After bioreduction, 73.6% of total chromium was adsorbed on the MR-1 impregnated Ca-alginate capsules. XPS results showed 85% of the adsorbed chromium was Cr(III). The mechanism for chromium removal over the MR-1-impregnated Ca-alginate capsules was proposed with the following steps: (1) Cr(VI) was bioreduced via the encapsulated MR-1; (2) the reduced soluble Cr(III) was adsorbed by alginate selectively. In the study, the Ca-alginate shell of the cabbage-like MR-1 impregnated capsules could be a shelter for encapsulated MR-1 to endure unfavorable conditions (e.g., low pH and high concentration of Cr(VI)) and immobilize the soluble chromium. Considering the obtained capsules derived from biomolecules were environment-friendly, the MR-1-impregnated Ca-alginate capsules were potential for the application in the remediation of environmental pollution.
Graphical abstract
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PROCESS BIOCHEMISTRY
·
2023
·
IF 4.4
Xiaoxue Zhang,Mengmeng Zhong,Rui Zhou,Wenxiu Qin,Youbin Si
Microbial reduction of Se(IV) to Se(0) is extremely important for the detoxification of selenium oxyanion, but the reductive mechanism is still controversial. In this study, the reduction of Se(IV) by Shewanella oneidensis MR-1 and Shewanella putrefaciens was systematically investigated. The results showed that excessive Se(IV) severely inhibited the growth of microorganisms and Se(IV) reduction. The extracellular accumulation of Nano-Se(0) particles was shown to be approximately 250–650 nm in diameter. Riboflavin facilitated Se(IV) reduction, while rotenone , as an electron inhibitor, could completely inhibit Se(IV) reduction, validating the extracellular electron transport process for biosynthesized Nano-Se(0). Importantly, the amorphous Nano-Se(0) synthesized by S. oneidensis MR-1 were mixtures of helical chains and Se 8 rings, while those synthesized by S. putrefaciens were mainly composed of helical chains. FTIR results demonstrated that Nano-Se(0) particles were wrapped by some proteins, organic substances and lipids , exhibiting superior dispersibility and biocompatibility. Biogenic Nano-Se(0) particles can also be considered for technological applications in various fields.
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ENVIRONMENTAL RESEARCH
·
2024
·
IF 7.7
Peiwen Li,Qiansheng Li,Hong Lu,Ze Fu,Jiti Zhou,Chenghao Sun,Xuehai Wang
Some nano-biochars (nano-BCs) as electron mediators could enter into cells to directly promote intracellular electron transfer and cell activities. However, little information was available on the effect of nano-BCs on SMX degradation. In this study, nano-BCs were prepared using sludge-derived humic acid (SHA) and their effects on SMX degradation by Shewanella oneidensis MR-1 were investigated. Results showed that nano-BCs (Carbon dots, CDs, <10 nm) synthesized using SHA performed a better accelerating effect than that of the nano-BCs with a larger size (10–100 nm), which could be attributed to the better electron transfer abilities of CDs. The degradation rate of 10 mg/L SMX in the presence of 100 mg/L CDs was significantly increased by 84.6% compared to that without CDs. Further analysis showed that CDs could not only be combined with extracellular Fe(III) to accelerate its reduction, but also participate in the reduction of 4-aminobenzenesulphonic acid as an intermediate metabolite of SMX via coupling with extracellular Fe(III) reduction. Meanwhile, CDs could enter cells to directly participate in intracellular electron transfer, resulting in 32.2% and 25.2% increases of electron transfer system activity and ATP level, respectively. Moreover, the activities of SMX-degrading enzymes located in periplasm and cytoplasm were increased by around 2.2-fold in the presence of CDs. These results provide an insight into the accelerating effect of nano-BCs with the size of <10 nm on SMX degradation and an approach for SHA utilization.
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高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2024
·
IF 12.2
Lisong Xia,Lei Cheng,Wenni Xi,Xiliang Zhang,Xianyang Shi
The environmental fate and risks of mononitrophenols (mono-NPs), the simplest nitrophenols (NPs) often found in aquatic environments, are profoundly influenced by anaerobic bioreduction and co-existing electron shuttles (ESs), but little is known about the underlying mechanisms. Here, we elucidate the pathways of anaerobic mono-NPs bioreduction by Shewanella oneidensis MR-1 and assess the effect of model ESs on these processes. We found that all three mono-NPs isomers could be readily reduced to their corresponding aminophenols by S. oneidensis MR-1 under anaerobic conditions. CymA, a core component of the Mtr respiratory pathway, performs a dynamic role in these bioreduction, which is highly dependent on the bioreduction kinetics. The exogenous addition of quinones was found to accelerate the mono-NPs bioreduction through interactions with key outer-membrane proteins (e.g., OmcA and MtrC), and all these processes matched well to linear free energy relationships (LFERs). Surprisingly, adding riboflavin did not influence the bioreduction of all three mono-NPs isomers, which may be due to the contribution of OmcA and MtrC to these bioreduction processes and their downregulated expression. This study enhances our understanding of the environmental fate of mono-NPs and their bioconversion processes, providing valuable insights for the bioremediation of nitrophenol-contaminated sites.
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INTERNATIONAL BIODETERIORATION & BIODEGRADATION
·
2024
·
IF 4.1
Liwen Zhang,Luyao Xi,Shuyu He,Huizi Wen,Shanyi Tan,Shaohua Chen
Bioremediation has garnered considerable interest due to its advantages of economy and no secondary pollution. However, the direct electron transfer rate between microorganisms and Cr(VI) is low. The bioreduction of Cr(VI) by Shewanella oneidensis MR-1 ( S. oneidensis ) in the presence of formylmethylflavin (FMF) was conducted to understand how FMF mediated the extracellular electron transfer process to improve Cr(VI) removal. In this study, FMF was firstly synthesized by modifing RF to increase its solubility and redox activity. The findings indicate that S. oneidensis /FMF exhibited better Cr(VI) removal performance compared to that of S. oneidensis . Under optimum conditions, 40 mg/L Cr(VI) could be completely removed by S. oneidensis /FMF within 120 h, while only 48.6% of Cr(VI) was removed by S. oneidensis , and the first order rate constant (k) for the Cr(VI) elimination by S. oneidensis /FMF (0.033 h −1 ) was about 4.1-fold greater than that of S. oneidensis (0.008 h −1 ). Moreover, the removal of Cr(VI) by S. oneidensis /FMF were dominated by reduction, and supplemented by adsorption and complexation. FMF enhance the extracellular electron transfer rate (EETR) was confirmed by electrochemical cyclic voltammetry (CV) and linear scanning voltammetry (LSV) experiments. This study emphasizes the potential important role of FMF in environmental bioremediation.
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CHEMOSPHERE
·
2021
·
IF 7.086
Fei Zhu,Yunhong Huang,Haiyan Ni,Jie Tang,Qi Zhu,Zhong-er Long,Long Zou
Microbially driven iron and sulfur geochemical cycles co-exist ubiquitously in subsurface environments and are of environmental relevance. Shewanella species (dissimilatory metal-reducing bacteria) are capable of reducing Fe(III)-(oxyhydr)oxide minerals and diverse sulfur sources using corresponding metabolic pathways and producing FeS secondary minerals. In spite of the ability in promoting bacterial extracellular electron transfer (EET), the specific role of FeS in mediating EET between microbe/mineral interface is still unclear. In this work, the electron-mediating function of biogenic FeS on promoting the reduction of ferrihydrite by S. oneidensis MR-1 using thiosulfate as sulfur source was investigated in terms of Fe(III) reduction percentage, X-ray diffraction and scanning electron microscopy . The results showed that the microbial ferrihydrite reduction was pH-dependent and positively correlated with the addition of thiosulfate . In the presence of thiosulfate , biogenic FeS in nano-scale were formed and deposited on the surfaces of S. oneidensis MR-1 and ferrihydrite to build an interfacial electron transfer bridge between them. The addition of either thiosulfate and in-vitro FeS could rescue the entirely inactivated ability of the mutant ( △omcA/mtrC ) in ferrihydrite reduction to some extent, but which was obviously inferior to the wild-type strain. Meanwhile, the effect of the biogenic FeS in-situ coating on the surfaces of S. oneidensis MR-1 cells on promoting microbial ferrihydrite reduction was significantly superior to the in-vitro ones. Thus, the in-situ formed biogenic FeS secondary minerals were demonstrated to mediate and accelerate interfacial electron transfer from S. oneidensis MR-1 cells to ferrihydrite through interfacing with the bacterial EET routes, especially Mtr pathway. This work provides an insight into the secondary minerals-mediating interfacial electron transfer between microbes and minerals in the presence of biological S (-II), which has important biogeochemical and environmental implications.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2019
·Vol. 26
·期 12
·12237-12246
·
IF 2.914
Yang Mi,Shi Xianyang
Biosynthesized nanocomposites are attracting growing interests because they are environmentally friendly. Ag 2 S nanoparticles (Ag 2 S NPs) are deposited in situ on the surfaces of TiO 2 nanotubes (TNTs) via Shewanella oneidensis MR-1 to form Ag 2 S/TNT nanocomposites. The prepared Ag 2 S/TNTs nanocomposites are characterized using high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy-dispersive X-ray spectroscopy. The results show that Ag 2 S NPs smaller than 8 nm are successfully synthesized and fabricated on the TNT surfaces with relatively uniform distribution. The catalytic performance of the Ag 2 S/TNT nanocomposites is evaluated for catalytic reduction in the presence of NaBH 4 and the photocatalytic degradation of 4-nitrophenol (4-NP) under visible light. The Ag 2 S/TNT nanocomposites show excellent catalytic activity and good stability in the 4-NP reduction process. The 4-NP degradation ratio reaches 98.3% in 50 min, and 87% conversion was achieved after eight cycles. The Ag 2 S/TNT nanocomposites also exhibit excellent photocatalytic activity for 4-NP at a rate of 0.69 h −1 , and the complete degradation of 4-NP was observed within 5 h. Therefore, this study offers an environmentally friendly approach to synthesize nanocomposites for practical applications.
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Frontiers of Environmental Science & Engineering
·
2025
·Vol. 19
·期 12
·1-16
·
IF 6.4
Zhao Biyi,Chen Wei,Chen Geng,Zhao Feng,Xiao Yong
Electroactive microorganisms are integral to biogeochemical cycles through extracellular electron transfer and have potential applications in environmental remediation. However, their long-term competitive interactions and evolutionary dynamics with non-electroactive microorganisms remain poorly understood. In this study, we conducted a 320-day cultivation experiment in which monocultures of the electroactive Shewanella oneidensis MR-1, the non-electroactive Citrobacter freundii An1, and their cocultures were compared under three single electron acceptor conditions: anaerobic (no exogenous electron acceptor), ferrihydrite, or oxygen. After 320 d, S. oneidensis MR-1 presented the highest relative abundance of 30.94% ± 0.74% in the ferrihydrite cocultures. S. oneidensis MR-1 maintained ferrihydrite reduction capacity after cultivation under all three conditions, indicating the long-term stability of its extracellular electron transfer. Moreover, no other phenotypic evolution was observed in S. oneidensis MR-1 after ferrihydrite or anaerobic cultivation. In contrast, both monocultured and cocultured S. oneidensis MR-1 exhibited enhanced adaptation to oxygen, characterized by increased growth rates, metabolic activity, and reduced cell aggregation. Notably, substrate consumption increased in monocultures but decreased in cocultures, suggesting an optimization of metabolic efficiency in the latter. Genome sequencing revealed mutations in genes associated with cell division, adenosine triphosphate synthesis, lactate metabolism, and flagellar/pilus expression in S. oneidensis MR-1. Interestingly, the ferrihydrite-adapted groups also exhibited enhanced adaptation to oxygen. 83.96% of mutations were shared across all culture systems and enriched in environmental signal-sensing pathways, indicating that parallel genomic evolution facilitated cross-environmental adaptation. Our findings reveal the ecological evolution of electroactive microorganisms in diverse redox environments and establish a foundation for engineering electroactive communities.
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ELECTROCHIMICA ACTA
·
2022
·
IF 7.336
Peng Zhang,Chenhui Yang,Zeng Li,Jia Liu,Xiang Xiao,Da Li,Chong Chen,Miao Yu,Yujie Feng
The high performance of microbial extracellular electron transfer (EET) is essential for bioremediation and bioenergy generation. Carbon dots (CDs) modified electroactive microorganisms showed an increased electron transfer efficiency. However, the influence of CDs’ concentration the EET has not been illustrated before. Herein, we reported that the addition of CDs increased the current generation by accelerating the EET process. The maximum current output of microbial electrochemical cells with the addition of CDs was increased by more than 5 times compared to pure Shewanella oneidensis MR-1. With CDs addition, the increase of biofilm immobilization and flavins secretion improved the direct and mediated EET process. Electrochemical analyses clarified that the combination of cytochrome c with CDs resulted in a faster electron transfer rate. The overload of CDs would restrict their promotion effect on EET, which may be due to their biotoxicity to bacteria. This work offered the insight of CDs’ concentration on the efficiency of EET, not only promoting the related applications of EET but also inspiring the regulation of microorganism function via nanomaterial.
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Frontiers in Microbiology
·
2016
·
IF 4.165
Han Rui,Li Fangbai,Liu Tongxu,Li Xiaomin,Wu Yundang,Wang Ying,Chen Dandan
It is widely recognized that the outer membrane c-type cytochromes (OM c-Cyts) of metal-reducing bacteria play a key role in microbial metal reduction processes. However, the in situ redox status of OM c-Cyts during microbial metal reduction processes remain poorly understood. In this study, diffuse-transmission UV/Vis spectroscopy is used to investigate the in situ spectral reaction of Cr(VI) reduction by c-Cyts in intact Shewanella oneidensis MR-1 cells under different incubation conditions. The reduced c-Cyts decreased transiently at the beginning and then recovered gradually over time. The Cr(VI) reduction rates decreased with increasing initial Cr(VI) concentrations, and Cr(III) was identified as a reduced product. The presence of Cr(III) substantially inhibited Cr(VI) reduction and the recovery of reduced c-Cyts, indicating that Cr(III) might inhibit cell growth. Cr(VI) reduction rates increased with increasing cell density. The highest Cr(VI) reduction rate and fastest recovery of c-Cyts were obtained at pH 7.0 and 30∘C, with sodium lactate serving as an electron donor. The presence of O2 strongly inhibited Cr(VI) reduction, suggesting that O2 might compete with Cr(VI) as an electron acceptor in cells. This study provides a case of directly examining in vivo reaction properties of an outer-membrane enzyme during microbial metal reduction processes under non-invasive physiological conditions.
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Environmental Science-Nano
·
2017
·Vol. 4
·期 12
·2395-2404
·
IF 6.047
Hong-Wei Luo,Xin Zhang,Jie-Jie Chen,Han-Qing Yu,Guo-Ping Sheng
Although the existence of Fe(III) (hydr)oxide nanoparticles (NPs) in natural environments has been recently recognized, their migration and transformation, which are substantially affected by the microbial reduction process, remain unclear. In this study, hematite bioreduction and magnetite formation induced by Shewanella oneidensis MR-1, a typical metal-reducing bacterial strain, were investigated using an integrated approach that combined experiments and computational simulations at the molecular scale. High-resolution transmission electron microscopy coupled with selected area electron diffraction (SAED), Raman spectroscopy and magnetic property analyses confirmed the biogenic magnetite formation. The electron paramagnetic resonance (EPR) spectra show a decay of the EPR intensity with incubation time, implying that the biotransformation of hematite to magnetite led to concurrent changes in their contents and local structures. X-ray absorption fine spectroscopy (XAFS) identified a time-resolved structural evolution of Fe(II)/Fe(III) coordination. The octahedral configuration upon Fe(II) production was subsequently validated by DFT calculations. Microbial reductive dissolution provided various intermediate states and new chemical environments regarding Fe(II)/Fe(III) complexes, such as monodentate and bidentate coordination patterns. Bioreduction caused the breakage of iron–oxygen bonds in hematite and the concomitant formation of Fe complexing microstructures for biogenic magnetite production. All these findings reveal the underlying mechanisms for the biotransformation of Fe minerals at the molecular scale and may allow us to better understand the speciation, immobilization and bioavailability of hematite NPs in natural systems.
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