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Effect of sulfate and nitrate on acetate conversion by anaerobic microorganisms in a freshwater sediment

Scholten, J.C.M. and Van Bodegom, P.M. and Vogelaar, J. and Van Ittersum, A. and Hordijk, K. and Roelofsen, W. and Stams, A.J.M. (2002) Effect of sulfate and nitrate on acetate conversion by anaerobic microorganisms in a freshwater sediment. FEMS Microbiology Ecology, 42, 375-385. ISSN 0168-6496.

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Acetate is quantitatively the most important substrate for methane production in a freshwater sediment in The Netherlands. In the presence of alternative electron acceptors the conversion of acetate by methanogens was strongly inhibited. By modelling the results, obtained in experiments with and without 13C-labelled acetate, we could show that the competition for acetate between methanogens and sulfate reducers is the main cause of inhibition of methanogenesis in the sediment. Although nitrate led to a complete inhibition of methanogenesis, acetate-utilising nitrate-reducing bacteria hardly competed with methanogens for the available acetate in the presence of nitrate. Most-probable-number enumerations showed that methanogens (2×108 cells cm-3 sediment) and sulfate reducers (2×108 cells cm-3 sediment) were the dominant acetate-utilising organisms in the sediment, while numbers of acetate-utilising nitrate reducers were very low (5×105 cells cm-3 sediment). However, high numbers of sulfide-oxidising nitrate reducers were detected. Denitrification might result in the formation of toxic products. We speculate that the accumulation of low concentrations of NO (<0.2 mM) may result in an inhibition of methanogenesis. [KEYWORDS: Competition; Denitrification; Inhibition; Methanogenesis; Most-probable-number enumeration; Sulfate reduction]

Item Type:Article
ID Code:11225
Deposited On:24 Nov 2011 01:00
Last Modified:24 Apr 2012 16:35

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