7. BACTERIOLOGY

摘要

The methanogenic archaeon Methanosarcina mazei Goel accumulates glycine betaine in response to hypersalinity but differs from most other methanoarchaea in having two gene clusters both encoding a potential glycine betaine transporter, Ota and Otb. We have created mutants with either ota or otb deleted to address their role in salt adaptation. The mutants were not impaired in growth at low or high salt, neither at 37℃ nor at lower temperatures. However, the Aota mutant was completely defective in glycine betaine transport demonstrating that Ota is the only glycine betaine transporter inM. mazei. The mutation in otb led to increased transcription of ota and thus increased transport and accumulation of glycine beta-ine suggesting a cross talk between the two transporters.