MICROBIOLOGICAL FORMATION OF VITAMIN B12: II. SYNTHESIS OF VITAMIN B12-ACTIVE SUBSTANCES BY BACTERIA ISOLATED FROM CLAMS

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Abstract
Vitamin B122occurred in certain seaweeds and this vitamin and other cobalamins were demonstrated regularly in marine invertebrates. A Bacillus and a Micrococcus isolated from fresh clams were selected for detailed study on the basis of their pronounced ability to form cobalamins, and because they appeared to be typical of the bacterial flora of these invertebrates. The Bacillus formed vitamin B12and other cobalamins, and this activity was stimulated by addition of Factor B and of certain purines or benziminazoles to the medium. With both organisms, 6-nitrobenziminazole proved particularly effective in stimulating formation of both vitamin B12and of other cobalamins, and Factor B stimulated this activity. Formation of cobalamins was associated with a marked decrease in Factor B. The cobalamins were associated with the bacterial cells, and no cobalamin synthesis by washed cell suspensions in phosphate buffer was observed.