Microbial Production of 2-Keto-<scp>l</scp>-Gulonic Acid from<scp>l</scp>-Sorbose and<scp>d</scp>-Sorbitol by<i>Gluconobacter melanogenus</i>

Abstract

The strain SPO1 producing 13 g of 2-keto-l-gulonic acid (2KGA) per liter was isolated as a spontaneous mutant of Gluconobacter melanogenus IFO 3293. For the enhancement of 2KGA productivity, we did further strain improvement studies of the mutant. As a result, the mutant U13, producing about 60 g of 2KGA per liter from 100 g of l-sorbose per liter, was obtained. In addition, the mutant Z84, producing about 60 g of 2KGA per liter from 100 g of d-sorbitol per liter, was also obtained. During the fermentation from l-sorbose and d-sorbitol, 5 to 10 g of l-idonic acid per liter was produced as a by-product, but l-idonic acid was converted to 2KGA before the end of fermentation.