Simultaneous saccharification and fermentation of amorphous cellulose to ethanol by recombinant Klebsiella oxytoca SZ21 without supplemental cellulase

A derivative of Klebsiella oxytoca M5A1 containing chromosomally integrated genes for ethanol production from Zymomonas mobilis (pdc, adhB) and endoglucanase genes from Erwinia chrysanthemi (celY, celZ) produced over 20 000 U endoglucanase l(-1) activity during fermentation. In combination with the native ability to metabolize cellobiose and cellotriose, this strain was able to ferment amorphous cellulose to ethanol (58-76% of theoretical yield) without the addition of cellulase enzymes from other organisms.