[Role of the nutrient medium components in regulating levansaccharase synthesis in Gluconobacter oxydans]

The effect of phosphate and acetate buffer systems on the growth of Gluconobacter oxydans and its synthesis of levansucrase was studied in nutrient media containing sorbitol. The intensification of constructive processes in media with an increased content of phosphate did not accelerate the enzyme biosynthesis by G. oxydans. As was shown in experiments with the intact cells of G. oxydans, the respiratory activity of the bacterium was stimulated in phosphate buffer supplemented with fructose. In contrast, acetate inhibited fructose oxidation and hindered the growth. At the same time, the synthesis of levansucrase increased. Such an increase was also found when the growth of G. oxydans was suppressed by sodium fluoride, an inhibitor of cellular metabolism. The extra synthesis of levansucrase useless during the growth on sorbitol should be attributed apparently to non-balanced growth of the bacterial culture caused by the suppression of respiration processes.