抄録
1. Thiamine propyl disulfide (TPD) was more effective than thiamine, and thiamine disulfide (TDS) was of the same activity as thiamine on the growth of L. ferementi in the Macias R medium containing cysteine, but in the medium without cysteine, both TPD and TDS were scarcely effective. In the medium containing sodium thiosulfate in place of cysteine, the same effects were observed.
2. TPD or TDS was easily converted to thiamine by preincubation with the cysteine contained in the Macias R medium. When the medium was inoculated with L. fermenti, it was showed that TPD was more effective than thiamine, but TDS was almost equally effective to thiamine. Cysteine in the medium can be replaced by thiosulfate.
3. The solution in which TPD or TDS had been previously reduced by cysteine to thiamine was added to the medium for L. fermenti and the growth-stimulating effects of TPD or TDS were found to be almost the same as thiamine.
4. It was confirmed using TPD-S35 (outer) that the propylmercaptan moiety produced from TPD during thiamine formation by cysteine became S-propylmercapto-L-cysteine and that this compound had no effect on the growth of L. fermenti.
5. Taking these findings into consideration, it was discussed on the reason why TPD was more effective than thiamine alone in the cysteine (+) Macias R medium on the growth of L. fermenti.
