抄録
A modification was made of the components of basal medium for the determination of thiamine with Lactobacillus viridescens. In place of tryptone and thiamine-free yeast extracts in APT medium reported by Deibel et al., commercially available polypepton and yeast extract were used after having been treated at 15lb for 25 minutes in an autoclave in the presence of an appropriate amount of sodium hydroxide, and then neutralized. It has been found that the assay method using the modified medium is as specific, reproducible, and convenient as that using APT medium. Comparative investigations of the activities of a variety of thiamine derivatives on L. viridescens were made under different conditions. Thiamine propyldisulfide, thiamine dicetylsulfate and thiamine diphosphate were as much active as, and S-benzoylthiamine monophosphate was less active than thiamine hydrochloride. S-Ben-zoylthiamine and O, S-dibenzoylthiamine showed a slight activity when autoclaved with the basal medium. A similar behavior was observed when thiamine derivatives dissolved in sterile water were added to the sterile modified medium. The activity of S-benzoylthiamine monophosphate seems to be higher in the modified medium than in APT broth. S-Benzoylthiamine and S-benzoylthiamine monophosphate were more active when autoclaved with the medium containing cysteine than without the substance.
