Abstract
The cleavage of oxythiamine to its moieties and the utilization of thiazole part as a precursor of thiamine by thiamine-synthesizing microorganisms has been already ascertained by the authors. On the other hand, growth of E.coli thiamine-less mutant also occured in the presence of oxythiamine after a certain lag period of the incubation in a medium deprived of thiamine. In this case decomposition of oxythiamine and formation of thiamine and an unidentified substance were observed by paper chromatography and paper ionophoresis and chemical assay. The change was also observed by cell homogenate of the E.coli mutant. It was enhanced by simultaneous addition of L-aspartate with oxythiamine. The unknown compound was positive to Dragendorff, ninhydrin, and bromophenol blue reagents and UV quenching test. It exerted a growth effect on thiamine-requiring microorganisms such as E.coli 70-23 or Kloeckera apiculata. Radioisotopic studies with uniformly labeled C^<14>-aspartic acid showed the incorporation of C^<14> into the unidentified substance and fumaric acid. From the results it would be supposed that the transformation of oxythiamine to thiamine by the bacteria occured by amination of hydroxyl group at position 4 of the pyrimidine part of the antagonist and the unknown compound was an intermediate, tentativery named, "thiaminosuccinic acid".
