Salmonella typhimurium forms adenylcobamide and 2-methyladenylcobamide, but no detectable cobalamin during strictly anaerobic growth

Under microaerophilic conditions Salmonella typhimurium, LT2 synthesizes co balamin, during which ,6-dimethylbenzimidazole is formed from riboflavin. W e report here that in an anoxic environment S. typhimurium did not form cob alamin, but rather adenylcobamide, 2-methyladenylcobamide, and cobyric acid . This indicated that S. typhimurium, like other microorganisms that synthe size 5,6-dimethylbenzimidazole from riboflavin, requires oxygen for the for mation of the cobalamin base.