Production of glucose-fructose oxidoreductase and ethanol by Zymomonas mobilis ATCC 29191 in medium containing corn steep liquor as a source of vitamins.
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 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.
Silveira
M M
MM
Instituto de Biotecnologia, Universidade de Caxias do Sul, Rio Grande do Sul, Brazil.
Wisbeck
E
E
Hoch
I
I
Jonas
R
R
D003470:Culture Media; D000431:Ethanol / Q000378:metabolism*; D005942:Gluconates / Q000378:metabolism; D010088:Oxidoreductases / Q000096:biosynthesis*; D013012:Sorbitol / Q000378:metabolism; D014815:Vitamins / Q000096:biosynthesis*; D017355:Zymomonas / Q000254:growth & development / Q000378:metabolism*
D003470:Culture Media; D005942:Gluconates; D014815:Vitamins; D000431:Ethanol; D013012:Sorbitol; D010088:Oxidoreductases; C074291:glucose-fructose oxidoreductase; C030691:gluconic acid