Studies on the Production of B Vitamins by Intestinal Bacteria of Fish-V

After cultivating carp with several test diets for 10 days, the amount of B12 in the intestinal contents was determined by the micro-bioassay method using Lactobacillus leichmannii. A considerable amount of B12 was observed in the intestinal contents of the fish fed on B12-free diets. Moreover, a remarkable increase of B12 was observed when the excised intestinal canal was incubated in vitro for 6 hours at 25°C. The addition of sulfanylamide to the diet did not always cause the decrease of B12 in the intestinal contents. These results indicate the production of B12 by microorganisms in the intestinal canal of carp.