Abstract
The biological activities of thiamine and related compounds for a strain (70-23) of Escherichia coli mutant were investigated by estimating the growth response in the range of a nearly minimal concentration. Bioautographically (by paper disc method), the minimal amounts of thiamine and its phosphoric esters for the growth response corresponded to 0.2 mμg of each compounds while those of the disulfide and S-acyl compounds of thiamine were much higher, but both of these compounds gave the same activities in the degree of 10 mμg. Turbidimetrically, the activities of the latter compounds were more labile than the former under a condition of incubation. The response curve for time course of the disulfide and S-acyl compounds showed lower activities for the half maximal growth compared with thiamine, while the maximal growths were equal to thiamine except dibenzoyl thiamine. Therefore it is assumed that these disulfide and S-acyl compounds are utilized for growth of the microorganism after transformation to thiamine or its phosphoric esters.
