THE FERMENTATIVE PRODUCTION OF L-VALINE BY BACTERIA

Abstract

1. More than ten strains of bacteria which are capable of producing large amounts of valine were selected under a screening program. The isolates from natural sources we classified as Paracolobacterum coliforme, P. intermedium, Escherichia coli, and Aerobacter aerogenes.
2. The production and accumulation of L-valine in P. coliforme and Brevibacterum ammoniagenes have been investigated rather in detail, showing the formation of up to 0.23 mole of valine from one mole of glucose.
3. The biosynthetic pathway of valine revealed in the valine-producing bacteria is similar to the known pathway of other microorganisms. It was made clear by experimental results that the enzymes responsible to the condensation of pyruvate in the valine-producing cells are active at pH 5.5 7.5 and different from the "orthodox" biosynthetic enzyme which is active at pH 8, as two enzymes are known in the reaction of acetolactate formation.
4. One of the mechanisms for the efficient production and accumulation of valine is ascribed to the action of an active acetolactate-forming enzyme which is present at least in the valine-producing cells and whose action is not suppressed by valine itself.