Zymomonas mobilis As Catalyst for the Biotechnological Production of Sorbitol and Gluconic Acid

Abstract

The conversion of glucose and fructose into gluconic acid (GA) and sorbitol (SOR) was conducted in a batch reactor with free (CTAB-treated or not) or immobilized cells of Zymomonas mobilis. High yields (more than 90%) of gluconic acid and sorbitol were attained at initial substrate concentration of 600 g/L (glucose plus fructose at 1:1 ratio), using cells with glucose-fructose-oxidoreductase activity of 75 U/L. The concentration of the products varied hyperbolically with time according to the equations (GA) = t(GA)max/(WGA + t), (SOR) = t (SOR)max/(WSOR + t), vGA = [WGA (GA)max]/(WGA + t)2 and vSOR = [WSOR (SOR)max]/(WSOR + t)2. Taking the test carried out with free CTAB-treated cells as an example, the constant parameters were (GA)max = 541 g/L, (SOR)max = 552 g/L, W GA = 4.8 h, W SOR = 4.9 h, v GA = 112.7 g/L·h and v SOR = 112.7 g/L·h.Index EntriesZymomonas mobilissorbitolgluconic acid