Biosynthesis of thiamine by Phycomyces blakesleeanus

Abstract

Phycomyces blakesleeanus was grown in a minimal glucose–asparagine broth medium supplemented with either 2-methyl-4-amino-5-hydroxymethylpyrimidine-4,7-14C or 4-methyl-5-(2-hydroxyethyl)-thiazole-2-14C and the corresponding non-labeled moiety of thiamine. Extracts of mycelia and of culture filtrates were tested for the presence of intermediates formed in the biosynthesis of thiamine by P. blakesleeanus. By combinations of ion-exchange and thin-layer chromatography, autoradiography, and bioautography, the following compounds were identified: 4-methyl-5-(2-phosphorylethyl)thiazole, 2-methyl-4-amino-5-phosphorylmethylpyrimidine, 2-methyl-4-amino-5-pyrophosphorylmethylpyrimidine, and thiamine monophosphate.