Abstract
Each of modified thiamine compounds ; thiamine-disulfide (I), thiamine propyl (II), tetrahydrofurfuryl (III) and 8-(methyl-6-acetyldihydrothioctate)(IV) disulfides, O-benzoylthiamine disulfide (V), diacetylthiamine (VI), dibenzoylthiamine (VII), S-benzoylthiamine monophosphate (VIII) and dicarboethoxythiamine (IX) was aseptically added to the broth for L. fermenti or Kl. apiculata. The growth-responses of both microorganisms after incubation for 20 or 18 hours were shown in Table 1. Kl. apiculata showed equal or a little stronger response to modified thiamine compounds having free OH in the thiazole moiety, than that to thiamine. Kl. apiculata can respond to O, S-disubstituted compounds, showing one-tenth to one-fifth the growth with compared to thiamine, while L. fermenti can not respond to modified compounds, unless cysteine is present in the broth. Even at the presence of cysteine, (VII), (IX), (V) and (VI) were incapable or very weak in stimulating the growth. L. fermenti seems to be lacking enzyme systems to convert modified compounds to thiamine but Kl. apiculata can utilize all the modified thiamine compounds except S-alkylthiamines as indicated in Table 2.
