Bacteria, methanogenic sediments

Pancost RD, Damste JSS, de Lint S, van der Maarel MJEC, Gottschal JC, The Medinaut Shipboard Scientific Party (2000) Biomarker evidence for widespread anaerobic methane oxidation in mediterranean sediments by a consortium of methanogenic archaea and bacteria. Appl Environ Microbiol... 

Roden, E. E. and R. G. Wetzel, 2003, Competition between Fe(III)-reducing and methanogenic bacteria for acetate in iron-rich freshwater sediments. Microbial... 

Fermentation may take place in the three major microbial subsystems of a sewer, i.e., the wastewater, the biofilm and the sediments (Figure 3.2). Sulfate-reducing bacteria are slow growing and are therefore primarily present in the biofilm and in the sediments, where sulfate from the wastewater may penetrate (Nielsen and Hvitved-Jacobsen, 1988 Hvitved-Jacobsen et al., 1998 Bjerre et al., 1998). However, as a result of biofilm detachment, sulfate reduction may, to some minor extent, take place in the wastewater. Methanogenic microbial activity normally requires absence of sulfate — or at least a low... 

Conrad R, Bak F, Seitz HJ, et al. 1989. Hydrogen turnover by psychrotrophic homoacetogenic and mesophilic methanogenic bacteria in anoxic paddy soil and lake sediment. FEMS Microbiol Ecol 62 285-94. 

During microbial action, kinetic isotope fractionations on the organic material by methanogenic bacteria result in methane that is highly depleted in typically with 5 C-values between -110 and -50%c (Schoell 1984, 1988 Rice and Claypool 1981 Whiticar et al. 1986). In marine sediments, methane formed by CO2 reduction is often more depleted in than methane formed by acetate fermentation in freshwater sediments. Thus, typical ranges for marine sediments are between -110 and -60%c, while those for methane from freshwater sediments are from -65 to -50%c (Whiticar et al. 1986 Whiticar 1999). 

Some volatile compounds such as methanethiol, dimethylsulfide and dimethyldisulfide have been shown to yield methane when they were added to anaerobic cultures derived from aquatic sediments (70. 71V Kiene et al. (22) showed that methane bacteria and sulfate-reducers competed for dimethyldisulfide when it was added at low concentrations to anaerobic aquatic sediments. They also isolated a methanogen that metabolized dimethyldisulfide to methane and carbon dioxide (72). Recently Oremland et al (22) detected trace amounts of ethane released from anoxic sediment slurries. This could be stimulated by the addition of ethanethiol or diethylsulfide and inhibited by the addition of bromoethanesulfonic acid which specifically inhibits methane bacteria. These results indicated that methane bacteria co-metabolized these two OSC. 

Glu 6, a major constituent of dissolved free amino acids (DFAA) in marine sediments [71], has been detected in red algae (Rhodophyta) [72] and as a potential osmolyte in several marine bacteria, for example obligatory aerobic heterotrophs [70] and methanogenic archaebacteria [8], N-methyl-/ -glutamate has been reported solely as a natural product from the cyanobacterium Prochloron didemni [96]. 

Risatti, J.B., Rowland, S.J., Yon, D., and Maxwell, J.R. (1984) Sterochemical studies of acyclic isoprenoids—XII. Lipids of methanogenic bacteria and possible contributions to sediments. In Advances in Organic Geochemistry (Schenck, P.A., and de Leeuw, J.W., eds.), pp. 93-103, Pergamon Press, Oxford, UK. 

Brassell S. C., Wardroper A. M. K., Thomson I. D., Maxwell J. R., and Eglinton G. (1981) Specific acyclic isoprenoids as biological markers of methanogenic bacteria in marine sediments. Nature 290, 693-696. 

Methanotrophs occur at the oxic-anoxic interface of methanogenic habitats, in symbiotic association with animals (Kochevar et al., 1992), and inside wetland plants (Bosse and Erenzel, 1997). Although methanotrophs dominate aerobic CH4 oxidation, NH4-oxidizing bacteria may account for a small amount of the CH4 oxidation activity in soils and sediments (Bodelier and Erenzel, 1999). 

Balderston W. L. and Payne W. J. (1976) Inhibition of methanogenesis in salt marsh sediments and whole-cell suspensions of methanogenic bacteria by nitrogenous oxides. Appl. Environ. Microbiol. 32, 264-269. 

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