초록
A methanotrophic bacterium, named SAD2, was isolated from a hydrogen sulfide (H<SUB>2</SUB>S)-rich anaerobic digester. Based on its 16S rRNA gene sequence, SAD2 belongs to Methylocaldum sp. SAD2 grew stably on methane/air mixtures containing 500 and 1000ppm of H<SUB>2</SUB>S, and showed H<SUB>2</SUB>S tolerance higher than those reported for Methylomicrobium album and Methylocystis sp. Exposure to 1000ppm or less H<SUB>2</SUB>S during SAD2 cell preparation did not affect the subsequent methanol production, while the presence of 1000ppm H<SUB>2</SUB>S in the methanol production process caused a 44-60% decrease in methanol concentration. When a biogas/air mixture containing about 500ppm or less H<SUB>2</SUB>S was used for methanol production by SAD2, 276-343mg/L of methanol was obtained with methane-to-methanol conversion efficiencies of 30-34%. This new isolate may be used in conversion of biogas to methanol without scrubbing of H<SUB>2</SUB>S.