Involvement of mercury methylation in microbial mercury detoxication.

A vitamin B12 requiring strain was isolated from Clostridium cochlearium T-2C which is known to synthesize various types of vitamin B12 including methylcobalamin and has an ability to methylate inorganic mercury. The vitamin B12 auxotroph lacking the mercury-methylating activity showed higher sensitivity to inorganic mercury than its original strain, while the sensitivity of both strains to methylmercury was relative low and essentially the same. These data seem to present affirmative evidence to postulate the physiological role of methylcobalamin-dependent methylation of mercury to be a process of detoxication.