Studies on the Production of B-Vitamins by Intestinal Bacteria of Fish IV : Production of Nicotinic Acid by Intestinal Bacteria of Carp

In order to determine how much intestinal bacteria synthesize nicotinic acid during growth, 209 strains of bacteria were isolated from intestinal canal of carp, and the production of this vitamin by these bacteria was examined. The results obtained were as follows. 1. Decrease of the nicotinic acid content in the medium was observed in 47 strains when they were cultivated in bouillon medium at 30°C for 24 hours. It was found that only a few bacteria could produce notable nicotinic acid under these conditions. All the 25 strains of bacteria, which can grow in Massen’s medium, produced nicotinic acid in some extent. (Table 1, 2) 2. Accumulation of nicotinic acid in the medium surpassed that of bacterial body, and the acid concentration reached to a maximum at about 2 days of cultivation. (Table 3, 4