ACTIVATION OF THE DISULFIDE FORMS OF THIAMINE AND ITS PHOSPHATES AS GROWTH FACTORS FOR LACTOBACILLUS FERMENTI

Publisher Website
Google Scholar
Abstract
The earlier finding on the unavailability of thiamine disulfide for L. fermenti (ATCC 9338) made by the agar plate method (Biochem. Z. 332(1): 77-80. 1959) was confirmed by the tube method, using a chemically defined medium. Neither thiamine disulfide (T-SS-T) nor the homomeric dissulfides of thiamine -orthophosphate or -pyrophosphate (cocarboxylase) support growth if added aseptically to the medium. Addition of relatively high levels of cysteine (460 [mu]g per 7 ml), ascorbic acid (10 mg per 7 ml) or triosereductone (5 mg per 7 ml) actiyate T-SS-T to growth factor for L. fermenti, Autoclaving the basal medium with cystine in it or steaming or autoclaving the T-SS-T solutions results in the same effect. T-SS-T is not a competitive inhibitor for thiamine and can be utilized by the bacterial cells in concentrations 10 times higher than those of thiamine. This is probably due to reduction of T-SS-T by the growing cells. Quantitative differences between growth promoting ability of different derivatives of thiamine can be attributed to the presence of varying amounts of the disulfide forms of the corresponding compounds in different preparations. After activation, nutritional values of the phosphorylated forms of thiamine were similar to that of thiamine; previously it was believed that cocarboxylase possessed about 30% higher activity, which would be, however, at variance with our present knowledge concerning the intracellular phosphorylation of thiamine. Among the known growth enhancement effects, the sparing action of ascorbic acid on thiamine utilization is now explained as an interplay between this reducing agent and thiamine as well as cystine, if present. This finding argues against the necessity of ascorbic acid participation in the pyruvate metabolism. On the other hand, growth stimulation with heat degradation products of glucose in the presence of phosphates and the preferred utilization of fructose and maltose cannot be accounted for by the interaction between reducing agents and thiamine disulfide.