Trace methane oxidation and the methane dependency of sulfate reduction in anaerobic granular sludge.

This study investigates the oxidation of labeled methane (CH(4)) and the CH(4) dependence of sulfate reduction in three types of anaerobic granular sludge. In all samples, (13)C-labeled CH(4) was anaerobically oxidized to (13)C-labeled CO(2), while net endogenous CH(4) production was observed. Labeled-CH(4) oxidation rates followed CH(4) production rates, and the presence of sulfate hampered both labeled-CH(4) oxidation and methanogenesis.