Production of glucose-fructose oxidoreductase and ethanol by Zymomonas mobilis ATCC 29191 in medium containing corn steep liquor as a source of vitamins

• Published in: Applied microbiology and biotechnology 2001-05, Vol.55 (4), p.442-445
• Main Authors: Silveira, M.M, Wisbeck, E, Hoch, I, Jonas, R
• Format: Article
• Language: English
• Subjects: Bacteria; Biological and medical sciences; Biotechnology; Cell growth; Corn; corn steep liquor; Culture Media; economic feasibility; Economics; enzymes; Ethanol; Ethanol - metabolism; ethanol production; Fundamental and applied biological sciences. Psychology; Gluconates - metabolism; gluconic acid; glucono-d-lactonase; glucose-fructose oxidoreductase; Methods. Procedures. Technologies; Microbial engineering. Fermentation and microbial culture technology; Oxidoreductases - biosynthesis; sorbitol; Sorbitol - metabolism; Vitamins; Vitamins - biosynthesis; yeast extract; Yeasts; Zymomonas - growth & development; Zymomonas - metabolism; Zymomonas mobilis
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s002530000569

Different concentrations of corn steep liquor (CSL) were tested in the cultivation of Zymomonas mobilis. Cell growth, ethanol production, and the formation of glucose-fructose oxidoreductase (GFOR) and glucono-delta-lactonase (GL), the enzymes responsible for the bio-production of gluconic acid and sorbitol, were examined. The cell yields using 25 g CSL l-1 and 40 g CSL l-1 (Y(X/S) approximately equal to 0.031 g g-1) were close to that obtained with 5 g yeast extract (YE)l-1. With 5 g CSL l-1 and 15 g CSL l-1, the nutritional limitation led to smaller Y(X/S). Using 100 g CSL l-1 produced an inhibitory effect on cell growth. Similar ethanol yields (92-95%) were calculated for each concentration of CSL and also for YE medium. The highest specific GFOR/GL activities (13.2-13.5 U g-1 dry cell) were reached with 25 g CSL l-1 and 40 g CSL l-1, values comparable to that achieved with 5 g YE l-1. The results confirm that CSL is an effective and cheap supplement for Z. mobilis medium, increasing the economic potential of a large-scale bio-production of sorbitol and gluconic acid by untreated Z. mobilis cells. The economic feasibility of the process is discussed.