Synthesis of vitamin B12 by various species of mycobacteria

The synthesis of Vitamin B12 by five reference strains of species of mycobacteria, the influence of cobalt upton the synthesis and the correlation between the phase of growth and quantitative biosynthesis of Vitamin B12 were studied. Assays were performed on cell extracts and culture filtrates using Lactobacillus leichmannii ATCC7830 (tube method). All five species synthesized Vitamin B12, which could be deomonstrated both in cell extracts and in the culture filtrates. An optimum accumulation of Vitamin B12 by BCG and M. phlei could be observed on the 30th day of cultivation. Addition of cobalt did not influence the growth of BCG and M. phlei, but markedly enhanced the production of Vitamin B12. Cells contained much more Vitamin B12 than culture filtrates did. Vitamin B12 levels in M. smegmatis, M. fortuitum and M. asiaticum were lower than those in BCG and M. phlei.