Abstract
1. Escherichia coli 26-43 (thiazole-requiring mutant) did not response to sulfur-containing amino acids and thiazolidine-4-carboxylic acid which had been reported to be the precursor of thiazole.
2. α-Amino-β-(4-methylthiazol-5-yl)propionic acid was active to Escherichia coli 26-43 and considered to be the possible precursor of thiazole.
3. Investigations to obtain the accumulated compound by Escherichia coli 26-43 and to decide the immediate biochemical lesion of this mutant were carried out but had not been successful.
