Previous work isolated anaerobic bacteria from timbers and drainage water in a gold mine. The present work identifies the predominant methanogen in the mine ecosystem as Methanobacterium bryantii and sulphate-reducing isolates as Desulphovibrio desulphuricans and Desulphotomaculum antarcticum. Laboratory studies using model systems evaluate the activity of methanogenic and sulphate-reducing bacteria in situ. Most probable numbers (MPN) of bacteria indicate 3.5 x 105 methanogenic and 7.9 x 103 sulphate-reducing bacteria/ml drainage water. MPN values g-1 timber were lower for methanogens but comparable for sulphate-reducers. Laboratory model systems predict methanogenesis as the likely dominant terminal reaction in the mine ecosystem. Maximum calculated rates of methane production were approximately 5 ml methane g-1 wood day-1, however actual rates would never attain this value owing to nutrient limitations and environmental restrictions. Analyses of gas samples extracted from sealed areas verified the presence of methane.

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