in Pseudomonas denitrificans and Rhodobacter capsulatus. Anaerobic pathway in which cobalt insertion is the first committed step towards cobalamin synthesis; [ 5 ] found in Salmonella typhimurium , Bacillus megaterium , and Propionibacterium freudenreichii subsp. shermanii . Either pathway can be divided into two parts: Corrin ring synthesis (differs in aerobic and