Abstract
The growth-inhibition of Kloeckera apiculata by phenyltriazinothiamine (PT-B_1) was not recovered by the addition of thiamine-HCl (Vitamins 33,488,1966). PT-B_1 in the broth was hydrolysed to phenylhydrazine, fomic acid and 2-methyl-4-amino-5-aminomethylpyrimidine, on heating especially by autoclaving. Phenylhydrazine inhibited the growth of Kl. apiculata 100 times stronger than PT-B_1 and the growth-inhibition by phenylhydrazine was not recovered by thiamine-HCl. The inhibition by PT-B_1 or phenylhydrazine was not observed when such a carbonyl compound as pyridoxal phosphate, pyruvate or glucose was added to the broth. From these results, the growth-inhibition of Kl. apiculata by PT-B_1 was well explained as the inhibition caused by phenylhydrazine hydrolysed from PT-B_1,not as the competitive inhibition by PT-B_1 itself.
