Escherichia coli KO11 and Klebsiella oxytoca P2 recombinants fermented sucrose to ethanol. In minimal medium with 2% or 12% added sucrose KO11 produced 75% and 41%, respectively, of the maximum theoretical yield (0.54g ethanol/g sucrose). In Luria-Bertani (LB) broth with up to 8% sucrose, KO11 presented a 94-96% yield and with 12% sucrose, KO11 presented about 69% yield (44.5g ethanol/L). P2 presented 55% of the theoretical maximum yield in minimal medium supplemented with 2% sucrose and 47% of the maximum in 12% sucrose. In LB broth with 2 or 4% sucrose, P2 presented 94-95% of the theoretical maximum yield, which fell to 73% with 8% added sucrose (31.4g ethanol/L) and 58% with 12% sucrose (37.5 g/L). Volumetric productivity in LB broth containing 2% sucrose was 0.41 g/L/h for KO11 and 1.1 g/L/h for P2, while in LB broth with 12% added sucrose, productivity was 0.96 g/L/h (KO11) and 1.4 g/L/h (P2). During fermentation of sugar cane juice by E. coli KO11 and K. oxytoca P2 produced 39.4 g/L and 42.1 g/L ethanol when supplemented with 0.5% yeast extract, micronutrients and thiamine. In sugar cane juice supplemented with LB broth ingredients, KO11 ethanol fermentation was inhibited with production of only 23.0 g ethanol/L, while P2 produced 44.2 g/L. Ethanol production by KO11 and P2, respectively, in sugarcane juice was a) 25.3 and 30.2 g/L with 0.2% ammonium sulfate, b) 24.9 and 31.6 g/L with ammonium sulfate and micronutrients, c) 25.6 and 37.5 g/L with ammonium sulfate, micronutrients and thiamine. During molasses fermentation E. coli KO11 presented low ethanol production and high lactic acid production. K. oxytoca P2 produced 25 g ethanol/L in molasses diluted 10-fold in water, with or without addition of 0.5% yeast extract, and 27.8 g/L with addition of LB broth ingredients after 96h. P2 produced 24.5, 26.9, and 28.0 g ethanol/L in molasses diluted 10-fold in vinasse, vinasse with 0.5% added yeast extract and with LB broth ingredients, respectively.
Escherichia coli KO11; Klebsiella oxytoca P2; Zymomonas mobilis; sucrose fermentation; ethanol fermentation
