Biosynthesis of Radioactive Vitamin B12Containing Cobalt60

Abstract
Addition of 2 ppm. of radioactive Co60 to broth medium inoculated with Streptomyces griseus resulted in the formation of radioactive vit. B12; as much as 79% of the added Co60 was recovered in the crystalline vit. Comparison of countercurrent analyses on color and on radioactivity distr. indicated the C06O to be an actual constituent of the vit. molecule, and not a contaminant.