Biosynthesis of cobalamins by cell suspensions of propionibacteria and streptomycetes.

The microbial synthesis of cobalamins first described by Rickes et al. (1948) as an attribute of Streptomyces griseus has been found to be a synthetic property of many microbial genera when grown in media containing cobalt salts (Darken, 1953). In all of the experiments described in the literature the microorganisms have been grown in cobalt-containing media, and no mention has been made of the biosynthesis of cobalamins by resting cells, e. g., nonproliferating cells. In this communication we wish to summarizesome of our observations on the biosynthesis of 5,6-dimethylbenzimidazole-hydroxocobalamin and a number of analogues of this vitamin by resting cells of propionibacteria and streptomycetes.