Abstract
The growth-stimulating activity of thiamine-8-(methyl-6-acetyl-dihydrothioctate)-disulfidehydrochloride (TATD) on Lactobacillus fermenti and Kloeckera apiculata was investigated when TATD was added aseptically to the broth. TATD showed the same activity as thiamine or thiamine disulfide on Lactobacillus at the concentrations between 1/4×10^<-7> and 1/4×10^<-3> M, whereas at the 1/4×10^<-2> M concentration, it indicated a marked growth-inhibition in the MaciasR broth containing cysteine. In the broth without cysteine, TATD had the same growth-stimulating activity as thiamine disulfide, though weaker than thiamine, at the concentrations between 1/4×10^<-7>and 1/4×10^<-4> M and also indicated the growth-inhibition at 1/4×10^<-3>-1/4×10^<-2> M. On Kloeckera assay TATD showed nearly the same activity as thiamine or thiamine disulfide at the concentrations between 1/4×10^<-7> 1/4×10^<-2> M, but no inhibitory effect even at such high concentration as 1/4×10^<-2> M. As the inhibition caused by TATD on Lactobacilli can be partially eliminated by the addition of thiamine, TATD itself seems to compete with thiamine but TATD is unstable, easily giving thiamine on its addition to the broth and therfore exact inhibition index couldn't be calculated.
