Abstract
Hydroxyethylthiamine (HET) and its related compounds showed the following activities on thiamine-requiring microorganisms for the growth. (1) HET, hydroxypropylthiamine (HPT) and hydroxyisobutylthiamine (HIBT) stimulated the growth of Lactobacillus fermenti at the same rate as thiamine, but the O-acylated compounds of HET, HPT and HIBT showed lower activities than thiamine. (2) HET, HPT and their O-acylated compounds stimulated the growth of Kloeckera apiculata at the same rate with thiamine, but HIBT and its O-acylated compounds showed lower activities than thiamine. (3) The growth stimulating activities of D- and L-HET on L. fermenti and Kl. apiculata were almost same as thiamine, but the activity of D-HET was a little higher than L-HET. (4) Kl. apiculata and Saccharomyces carlsbergensis, grown in the broth containing HET, accumulated thiamine and HET per se in cells. HET, HPT and HIBT proved to be inhibitory to the growth of Sacch. carlsbergensis to the same extent as thiamine, but the O-acylated compounds of HET, HPT and HIBT showed lower inhibition than thiamine. The growth inhibitions by HET, HPT and HIBT were reversed by the addition of pyridoxine.
