Abstract
Thiamine, when incubated with Lactobacillus fermenti hsarvested from thiamine-poor broth, was quickly uptaken by cells; time course of increase of both the total and free thiamine in cells were similar and phosphorylated thiamine was found to be predominant over free thiamine. Thiamine-uptake by Lactobacilli cells, when pyrithiamine or Amprolium was added, was more or less inhibited; pyrithiamine showed not only strong inhibition of thiamine-uptake but also decrease of phosphorylated thiamine, while Amprolium had weak inhibition of thiamine-uptake with negligible effect to phosphorylation of thiamine. Lactobacilli cells, however, when preincubated with pyrithiamine or Amprolium, were demonstrated to uptake thiamine on incubation with thiamine to the same extent as cells without preincubation with antithiamine compounds; therefore competitive inhibition of thiamine-uptake by cells was proved only when thiamine and pyrithiamine (or Amprolium) were added to the uptake process. Competitive uptake of thiamine and pyrithiamine (or Amprolium) by cells on incubation was also demonstrated by chemical determination of thiamine and antithiamine compounds. (Received Nov. 24,1970)
