In silico description of cobalt and nickel assimilation systems in the genomes of methanogens

Chellapandi, P.

doi:10.1007/s11693-011-9087-2

Cited by 11 publications

(5 citation statements)

References 48 publications

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“…Intracellular reduction of metal ions involves transport of metal ions into the cell cytoplasm, and this process is mediated by membrane transport proteins (Chellapandi, 2011). Toxic metals have no uptake systems for them to enter the cells using channels designed for other ions and organic molecules.…”

Section: Discussionmentioning

confidence: 99%

Reduction of hexavalent chromium by the thermophilic methanogen Methanothermobacter thermautotrophicus

Singh

Dong

Liu

et al. 2015

Geochimica et Cosmochimica Acta

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Despite the significant progress on iron reduction by thermophilic microorganisms, studies on their ability to reduce toxic metals are still limited, despite their common co-existence in high temperature environments (up to 70°C). In this study, Methanothermobacter thermautotrophicus, an obligate thermophilic methanogen, was used to reduce hexavalent chromium. Experiments were conducted in a growth medium with H2/CO2 as substrate with various Cr6+ concentrations (0.2, 0.4, 1, 3, and 5 mM) in the form of potassium dichromate (K2Cr2O7). Time-course measurements of aqueous Cr6+ concentrations with the 1, 5-diphenylcarbazide colorimetric method showed complete reduction of the 0.2 and 0.4 mM Cr6+ solutions by this methanogen. However, much lower reduction extents of 43.6%, 13.0%, and 3.7% were observed at higher Cr6+ concentrations of 1, 3 and 5 mM, respectively. These lower extents of bioreduction suggest a toxic effect of aqueous Cr6+ to cells at this concentration range. At these higher Cr6+ concentrations, methanogenesis was inhibited and cell growth was impaired as evidenced by decreased total cellular protein production and live/dead cell ratio. Likewise, Cr6+ bioreduction rates decreased with increased initial concentrations of Cr6+ from 13.3 to1.9 µM h−1. X-ray absorption near-edge structure (XANES) spectroscopy revealed a progressive reduction of soluble Cr6+ to insoluble Cr3+ precipitates, which was confirmed as amorphous chromium hydroxide by X-ray diffraction and selected area electron diffraction pattern. However, a small fraction of reduced Cr occurred as aqueous Cr3+. Scanning and transmission electron microscope observations of M. thermautotrophicus cells after Cr6+ exposure suggest both extra- and intracellular chromium reduction mechanisms. Results of this study demonstrate the ability of M. thermautotrophicus cells to reduce toxic Cr6+ to less toxic Cr3+ and its potential application in metal bioremediation, especially at high temperature subsurface radioactive waste disposal sites, where the temperature may reach ∼70°C.

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Section: Discussionmentioning

confidence: 99%

Reduction of hexavalent chromium by the thermophilic methanogen Methanothermobacter thermautotrophicus

Singh

Dong

Liu

et al. 2015

Geochimica et Cosmochimica Acta

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“…Methanosarcina mazei Go1 has in its genome the pathway to assimilate W, specifically, by two tungsten-specific transporter proteins, torB and torP (Chellapandi 2011). In the presence of 100 lM of Cd, Methanosarcina acetivorans increases the intracellular levels of cysteine, sulphide and coenzyme M, indicating that this microorganism might have a metal resistance mechanism involving thiol molecules.…”

Section: Microbial Resistance Mechanisms To Heavy Metalsmentioning

confidence: 99%

Methanogens, sulphate and heavy metals: a complex system

Paulo

Stams

Sousa

2015

Rev Environ Sci Biotechnol

125

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Anaerobic digestion (AD) is a well-established technology used for the treatment of wastes and wastewaters with high organic content. During AD organic matter is converted stepwise to methanecontaining biogas-a renewable energy carrier. Methane production occurs in the last AD step and relies on methanogens, which are rather sensitive to some contaminants commonly found in wastewaters (e.g. heavy metals), or easily outcompeted by other groups of microorganisms (e.g. sulphate reducing bacteria, SRB). This review gives an overview of previous research and pilot-scale studies that shed some light on the effects of sulphate and heavy metals on methanogenesis. Despite the numerous studies on this subject, comparison is not always possible due to differences in the experimental conditions used and parameters explained. An overview of the possible benefits of methanogens and SRB co-habitation is also covered. Small amounts of sulphide produced by SRB can precipitate with metals, neutralising the negative effects of sulphide accumulation and free heavy metals on methanogenesis. Knowledge on how to untangle and balance sulphate reduction and methanogenesis is crucial to take advantage of the potential for the utilisation of biogenic sulphide as a metal detoxification agent with minimal loss in methane production in anaerobic digesters.

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“…In contrary, the concentrations of Se were below the recommended concentrations (Table 3) for all the reactors due to the low concentration of this metal in the substrate (Table 1). Selenium is reported as an essential component for a variety of enzymes and is important for the growth of several methanogens [31,33]. Therefore, higher Se concentrations were expected to be found after the addition of CTES.…”

Section: Trace Metal Analysesmentioning

confidence: 99%

Biogas Production from Food Residues—The Role of Trace Metals and Co-Digestion with Primary Sludge

2020

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The majority of municipal Wastewater Treatment Plants (WWTPs) in Sweden produce biogas from sewage sludge. In order to increase the methane production, co-digestion of internal sludge with Organic Fraction of Municipal Solid Waste (OFMSW) might be feasible in the future. The objective of this study was therefore to find a beneficial solution for the utilization of OFMSW at the WWTP in Varberg, Sweden. The effects of co-digesting primary sludge (PS) and OFMSW collected in the municipality, in different mixing ratios, were investigated by semi-continuous anaerobic digestion assays. Furthermore, the effects of the addition of a commercial trace elements mixture solution (CTES), available on the market in Sweden, were also examined. Co-digestion of OFMSW and PS resulted in specific methane yields of 404, 392, and 375 NmL CH4/g volatile solids (VS), obtained during semi-continuous operations of 301, 357 and 385 days, for the reactors fed with OMFSW:PS ratio of 4:1, 3:1, and 1:1, and at maximum organic loading rates (OLRs) achieved of 4.0, 4.0 and 5.0 gVS/L/d, respectively. Furthermore, mono-digestion of OFMSW failed already at OLR of 1.0 gVS/L/d, however, an OLR of 4.0 gVS/L/d could be achieved with addition of 14 µL/g VS Commercial Trace Element Solutions (CTES) leading to 363 mL CH4/g VS methane production. These experiments were running during 411 days. Hence, higher process efficiency was obtained when using co-digestion of OFMSW and PS compared to that of OFMSW in mono-digestion. Co-digestion is a more feasible option where a balanced Carbon/Nitrogen (C/N) ratio and nutrient supply can be maintained.

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In silico description of cobalt and nickel assimilation systems in the genomes of methanogens

Cited by 11 publications

References 48 publications

Reduction of hexavalent chromium by the thermophilic methanogen Methanothermobacter thermautotrophicus

Reduction of hexavalent chromium by the thermophilic methanogen Methanothermobacter thermautotrophicus

Methanogens, sulphate and heavy metals: a complex system

Biogas Production from Food Residues—The Role of Trace Metals and Co-Digestion with Primary Sludge

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