Kinetic mechanism for the ability of sulfate reducers to out-compete methanogens for acetate
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- Schönheit, P., Kristjansson, J.K. & Thauer, R.K. Arch. Microbiol. (1982) 132: 285. doi:10.1007/BF00407967
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Methanosarcina barkeri and Desulfobacter postgatei are ubiquitous anaerobic bacteria which grow on acetate or acetate plus sulfate, respectively, as sole energy sources. Their apparent Ks values for acetate were determined and found to be approximately 0.2 mM for the sulfate-reducing bacterium and 3 mM for the methanogenic bacterium. In mixed cell suspensions of the two bacteria (adjusted to equal Vmax) the rate of acetate consumption by D. postgatei approached 15-fold the rate of M. barkeri at low acetate concentrations. The apparent inhibition of methanogenesis was of the same order as expected from the different Ks value for acetate. Difference in substrate affinities can thus account for the inhibition of methanogenesis from acetate in sulfate-rich environments, where the acetate concentration is well below 1 mM.