Abstract
Growth of Lactobacillus arabinosus, Lactobacillus casei, Streptococcus faecalis, and Leuconostoc mesenteroides were investigated using alanine-free synthetic media containing essential vitamins. These four lactobacilli required vitamin B_6 for their growths. So the growth promoting effects of pyridoxal, pyridoxamine and pyridoxine were compared. In the absence of vitamin B_6,alanines had varying effects on the growth. Any form of alanines had no effect for L. casei and a little effect for L. arabinosus. DL-Alanine promoted the growth of Stc. faecalis sufficiently but either D- or L-alanine remained ineffective. For Leuc. mesenteroides alanines were moderately effective. On the other hand, D-alanine exhibited inhibitory effect on the growth of L. casei in a semisynthetic medium. From these experimental results, it can be said that for the studies of anti-vitamin B_6 activities of various compounds, the alanine-free synthetic media are more preferable to the semisynthetic media.
