Open AccessHydrogen metabolism and sulfate‐dependent inhibition of methanogenesis in a eutrophic lake sediment (Lake Mendota)
Author(s) -
Conrad Ralf,
Lupton F.S.,
Zeikus J.G.
Publication year - 1987
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1987.tb02346.x
Subject(s) - methanogenesis , sulfate , bicarbonate , anoxic waters , environmental chemistry , metabolism , eutrophication , incubation , methane , chemistry , sediment , biology , ecology , biochemistry , nutrient , organic chemistry , paleontology
Hydrogen metabolism was studied in anoxic sediments of the stratified Lake Mendota; using a method which allowed the measurement of in situ H 2 concentrations and the headspace‐free analysis of turnover of dissolved H 2 . Addition of sulfate resulted in partial but immediate inhibition of H 2 ‐dependent methanogenesis. Sulfate addition did not result in an immediate decrease in the steady state concentration of dissolved H 2 , nor did it significantly stimulate the rate constant of H 2 turnover. Sulfate‐induced decrease in dissolved H 2 was only observed after prolonged incubation or when endogenous H 2 production was stimulated by added glucose. The turnover of the in situ H 2 accounted for only 14% of the H 2 ‐dependent methanogenesis from bicarbonate. While rates of methanogenesis increased during the season, rates of H 2 turnover decreased, accounting for only 2% of the H 2 ‐dependent methanogenesis at the end of summer stratification. These observations indicate that increasing proportions of CH 4 were formed from H 2 being directly transferred in syntrophic methanogenic associations. The rapid inhibition of H 2 ‐dependent methanogenesis by exogenous sulfate may be explained at least partially by assuming methanogenic associations in which syntrophic sulfate reducers change their metabolism from fermentative H 2 production to sulfate reduction.