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

Isolation of Vitamin B₁₂ Synthesizing Bacteria and Their Bacteriological Properties

Abstract

In preceding papers, the authors studied on the production of B-vitamins by intestinal bacteria of carp. This paper deals with the vitamin B₁₂ synthesizing ability of intestinal bacteria. Of the 198 strains of bacteria isolated from the intestinal canal of carp, the vitamin B₁₂ synthesizing capacity was researched. Concerning the 5 strains having a comparatively high synthesizing capacity, the vitamin B₁₂ content of intra- and extra bacterial cells were studied. The results obtained were as follows;
1. Of all the strains isolated from the intestinal canal of carp, the number of rods ex-ceeded that of coccus, and the ratio of both type of bacteria was shown to be nearly equal. (Table 1)
2. About half of intestinal bacteria produced some vitamin B₁₂, while no vitamin B₁₂ decomposing bacteria could be found in this study. (Table 2)
3. Intestinal bacteria of high productive ability of vitamin B₁₂ belongs mostly to Gram-negative rods, and they show a pretty high level of B₁₂-production, though not so remarkable as is to be seen in Actinomyces.
4. Vitamin B₁₂ content in the bacterial cells increased gradually during growth, while the vitamin B₁₂ in the culture medium reached to a highest level after 6 hours of incubation, and after that time almost no increase was to be observable. (Table 4 and Fig. 1)