New Gluconobacter oxydans strain with high tolerance to D-sorbitol, useful for converting D-sorbitol to L-sorbose in the production of ascorbic acid

Gluconobacter oxydans strain (I) with high tolerance to D-sorbitol, obtained from a low-tolerance strain by stepwise cultivation at increasing D-sorbitol concentrations, is new. Independent claims are also included for the following: (1) a semicontinuous process for producing L-sorbose, comprising: (a) inoculating a medium containing up to 38 wt.% D-sorbitol with a G. oxydans bacterium and culturing the bacterium until D-sorbitol conversion ceases; (b) isolating L-sorbose from a major portion of the culture broth; (c) using the remaining portion of the culture broth to inoculate a fresh medium in a ratio of 1:4-8, giving a mixture containing up to 38 wt.% D-sorbitol, and culturing the bacterium until D-sorbitol conversion ceases; and (d) isolating L-sorbose from the culture broth; and (2) a process for producing 2-keto-L-gulonic acid, comprising converting D-sorbitol to L-sorbose by the process of (1) and converting the L-sorbose either in situ or after isolation, to 2-keto-L-gulonic acid in a conventional manner. Die Erfindung betrifft D-Sorbit-hochtolerante Bakterien der Art Gluconobacter oxydans; Verfahren zu deren Herstellung; sowie ein Verfahren zur halbkontinuierlichen fermentativen Produktion von L-sorbose aus D-Sorbit.