Abstract
The growth of Lactobacillus fermenti 36 and Kloeckera apiculata which both require thiamine for their growth, was checked on the broth aseptically added with dihydrothiamine. It showed 1/100 growth-stimulating activity on Lactobacillus and 1/10 activity on Kloeckera compared to that of thiamine. Both n- and ps-dihydrothiamine indicated nearly the same activity but at the high concentration such as 10^<-2>M (x1/4) especially on Kloeckera, inhibition of growth was markedly observed, while thiamine had no inhibitory effect at higher concentrations. Two spots of Rf 0 (thiamine) and Rf 0.75 (dihydrothiamine) were detected by bioautography of pure sample of dihydrothiamine developed on a paper-strip with isoamyl-alcohol・pyridine・H_2O (5 : 1 : 3) and it was also demonstrated by the two-dimensional bioautography that dihydrothiamine was easily oxidized to thiamine on the paper-strip during the process of development. It was concluded, therfore, that the apparent growth stimulation by dihydrothiamine was based on its conversion into thiamine.
