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Zentralbl Mikrobiol. 1984;139(5):335-42.

Production of cyanocobalamine by Azotobacter chroococcum.


A strain of Azotobacter chroococcum was found to produce a considerable amount of cyanocobalamine especially when cultivated in a medium enriched with 0.3% ammonium chloride. Maximal production of the vitamin was achieved after six days of incubation in static cultures. The organism required molybdenum, iron (Fe++), cobalt and ascorbic acid for optimal production of cyanocobalamine. The initial supplementation of the medium with cyanocobalamine did not affect the formation of the vitamin. The least concentration of ascorbic acid tested greatly initiated the production of vitamin B12. Higher concentrations were not effective. In the presence of molybdenum, iron, cobalt and ascorbic acid maximal secretions of cyanocobalamine was attained in the presence of 3% sucrose or an amount of hydrolyzed rice-bran containing 2% sugar. Higher concentration of rice-bran was toxic to the organism.

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