Abstract
Specific activity of thiaminase II reached 150nmol/ min/mg protein at the logarithmic growth phase, when B. aneurinolyticus was grown in a medium containing 0.1μM thiamin or 2-methyl-4-amino-5-hydroxymethylpyrimidine (OMP). The thiaminase II activity from cells grown in the medium containing 3μM thiamin or OMP was 0.6% Of that in the 0.1μM thiamin or OMP medium, while in the medium containing 0.3μM thiamin or OMP the growth was 1.7 times as high as that at 0.1μM thiamin or OMP. Similar effect was observed in thiamin-analogues, quinolinothiamin, heteropyrithiamin, dimethialium and pyrithiamin, but oxythiamin, amprolium, pyrimidinylcysteine, pyrimidinylthiophenol and thiazole were not effective. After thiamin, OMP or thiamin-analogues effective for the growth was taken up by the cells, 80 to 95% Of intracellular thiamin occurred as thiamin pyrophosphate. The increase of thiaminase II activity, when B. aneurinolyticus was grown in the 0.1μM thiamin medium, was completely repressed by chloramphenicol.
