The role of vitamin B6 in the synthesis of tryptophane from indole and anthranilic acid by Lactobacillus arabinosus.

Lactobacillus arabinosus has the ability to synthesize several amino acids when adequate quantities of vitamin Bg are included in the medium (1, 2) ; however, the requirement of this organism for tryptophane is apparently not affected by the addition of vitamin 136 (2). Earlier studies showed that indole and anthranilic acid have appreciable tryptophane activity for L. arabinosus (3-7) but not for Streptococcus faecalis R (3,7). Serine enhanced the activity of indole for L. arabinosus when tested with a purified amino acid medium, but no increase in the tryptophane activity was noted when serine was added to a casein hydrolysate medium (7). Tatum and associates (8-10) have observed that serine is necessary for the synthesis of tryptophane from indole by certain Neurospora mutants, while Umbreit et al. (11) have shown that pyridoxal phosphate functions as a coenzyme for Neurospora in the synthesis of tryptophane from indole. In the present study the influence of pyridoxine, pyridoxal, and pyridoxamine and other constituents of the medium on the biosynthesis of tryptophane from indole and anthranilic acid by Lactobacillus arabinosus was investigated.