SPECIFICITY OF THE VITAMIN B 12 REQUIREMENT IN CERTAIN MARINE BACTERIA

Publisher Website
Google Scholar
Abstract
The response of 21 strains of vitamin B12-requiring marine bacteria to analogues of vitamin B12 was studied. Benzimidazole analogues of cyanocobalamin were most active for all bacteria followed by methylmercapto- and methyladenine analogues. Pseudovitamin B12, cobalamin phosphoribose, and factor B were inactive for all but a few strains. Antivitamin B12 activity was demonstrated by the adenine-containing analogues for certain cultures. All but three of the strains were able to replace completely their requirement for vitamin B12 with methionine, whereas deoxyribosides were inactive for all. A Flavobacteriumsp. which spared the vitamin requirement with methionine, responded to pseudovitamin B12 in the presence of the amino acid, but not in its absence. It was suggested that pseudovitamin B12 is unable to carry on the methyl group synthetic function of vitamin B12 with this bacterium, but can substitute for the vitamin in an unknown second function.