title: Biosynthesis of corrinoids. Concerning ithe origin of the methyl groups in vitamin B 12 .
mesh_terms: D002247:Carbon Isotopes; D008745:Methylation; D011424:Propionibacterium / Q000378:metabolism; D014805:Vitamin B 12 / Q000096:biosynthesis*
chemical_list: D002247:Carbon Isotopes; D014805:Vitamin B 12