Methanogenesis in Big Soda Lake, Nevada: an Alkaline, Moderately Hypersaline Desert Lake

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Abstract
Incubated sediment slurries from Big Soda Lake, Nevada, USA, produced significant levels of CH4 and production was inhibited by 2-bromoethanesulfonic acid and by autoclaving. Methane production was stimulated by methanol, trimethylamine and, to a lesser extent, methionine. Surprisingly, hydrogen, acetate and formate amendments provided only slight or no stimulation of methanogenesis. Methane production by sediment slurries had a pH optimum of 9.7. A methanol-grown enrichment culture containing a small, epifluorescent coccus as the predominant organism was recovered from sediments. The enrichment grew best when FeS or autoclaved sediment particles were included in the media, had a pH optimum of 9.7 and produced 14CH4 from 14CH3OH. The methane formed by methanol-grown enrichment cultures was depleted in 13C by 72-77.permill. relative to the methanol.