title: Why do sulfate-reducing bacteria outcompete methanogenic bacteria for substrates?
abstract: The apparent Ksvalues for H2of several phylogenetically distant strains of both methanogenic bacteria and sulfate-reducing bacteria were measured. The sulfate reducers had Ksvalues of about 2 μM whereas the Ksvalues of the methanogens were 6-20 μM. This indicates that probably all sulfate-reducing bacteria have a higher substrate affinity for H2than the methanogenic bacteria. Difference in substrate affinity can thus account for the inhibition of methanogenesis from H2and CO2in sulfate-rich ecosystems (mainly saltwater marshes), where the H2concentration is well below 5 μM. Possible explanations for this general phenomenon are discussed.
authors.affiliation: Institute of Biology, University of Iceland, Grensasvegur 12, 108, Reykjavik, Iceland.
authors.forename: J K
authors.initials: JK
authors.lastname: Kristjansson
authors.affiliation: Fachbereich Biologie/Mikrobiologie, Philipps-Universität Marburg, Lahnberge, D-3550, Marburg/Lahn, FRG.
authors.forename: P
authors.initials: P
authors.lastname: Schönheit