Bioconversion of glucose and fructose to sorbitol and gluconic acid by untreated cells of Zymomonas mobilis

• Published in: Journal of biotechnology 1999-10, Vol.75 (2), p.99-103
• Main Authors: Silveira, Mauricio M, Wisbeck, Elisabeth, Lemmel, Claudia, Erzinger, Gilmar, Lopes da Costa, José Paulo, Bertasso, Marcelo, Jonas, Rainer
• Format: Article
• Language: English
• Subjects: Bioconversions. Hemisynthesis; Biological and medical sciences; Biotechnology; Enzyme inhibition; Enzyme kinetics; Fermentation; Fructose; Fructose - metabolism; Fundamental and applied biological sciences. Psychology; Gluconates - metabolism; Gluconic acid; Glucose; Glucose - metabolism; Glucose–fructose oxidoreductase; Metabolism; Methods. Procedures. Technologies; Organic acids; Sorbitol; Sorbitol - metabolism; Zymomonas - growth & development; Zymomonas - metabolism; Zymomonas mobilis
• ISSN: 0168-1656; 1873-4863
• DOI: 10.1016/S0168-1656(99)00149-2

The bioconversion of glucose and fructose to gluconic acid and sorbitol, respectively, by the enzymes glucose–fructose oxidoreductase (GFOR) and glucono-δ-lactonase (GL), contained in untreated cells of Zymomonas mobilis ATCC 29191, was investigated in batch runs with glucose plus fructose concentrations ( S 0) varying from 100 to 750 g l −1 in equimolar ratio. When S 0 was increased to 650 g l −1, the yields were improved, reaching a maximum of 91% for both products, with productivities of 1.6 and 1.5 g g −1 cell h −1 for gluconic acid and sorbitol, respectively. Above this level ( S 0=750 g l −1), no further improvement in yields was observed and productivities decreased due to the longer process time. The high yields of bioconversion runs with S 0≥650 g l −1 are a consequence of the sequential inhibition of the normal metabolism of Z. mobilis by substrates and products, resulting in preferential utilization of substrates via the GFOR/GL system.