Biosynthesis of vitamin B12 by Propionibacterium shermanii IV. Vitamin B12 and porphyrin synthesis in relation to the metabolic activities of the bacterium

The bacterial cell pool contains 16 amino acids. No qualitative change appeared in the amino acid pool at different stages of growth. No amino acids were liberated from the cell pool into the culture medium. Pyruvic and α-ketoglutaric acids were detected in the culture medium and cell pool of Propionibacterium shermanii. Bacterial growth, vitamin B₁₂, and coproporphyrin III synthesis increased with increasing age of the culture. A part of the synthesized porphyrin is released into the culture medium. Glucose, the total nitrogen content of the culture medium, ammonia nitrogen, amino acid nitrogen, methionine and glycine decreased gradually with the increase in the age and the bacterial dry weight of the culture. Succinic acid appeared on the 4^th day and increased with age. Acetic and propionic acids were the only detectable volatile acids. The ratio of propionic to acetic acid was about 3:1 (w/w).