Ethanolic fermentation of sucrose, sugarcane juice and molasses by Escherichia coli strain ko11 and Klebsiella oxytoca strain P2

Abstract

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.

Use of sugarcane molasses “B” as an alternative for ethanol production with wild-type yeast Saccharomyces cerevisiae ITV-01 at high sugar concentrations

“…These results were similar to those reported previously for sugarcane juice and molasses media [15] where final ethanol concentrations were 39-42 g L -1 when modified strains of Escherichia coli KO11 and Klebsiella oxytoca P2 were used. Low ethanol production obtained with sucrose and glucose could be due to a lack of nutrients in the medium, while molasses ''B'', with its higher vitamin and mineral contents, gave better results.…”

“…The most used microorganism for ethanol production is Saccharomyces cerevisiae, but some studies have also been made with bacteria like Zymomonas mobilis or some Eschericia coli mutants [15]. They have some limitations in their capacity to use several substrates [2] and also in ethanol and sugar concentration resistance compared to S. cerevisiae yeast.…”

Ethanol production in Brazil: a bridge between science and industry

“…Currently, the main industrial route used for ethanol production worldwide is the microbiological process, also referred as alcoholic or ethanolic fermentation 12, 13, 14, 15. During this process, sugars are converted into ethanol, energy, cellular biomass, CO 2 and other byproducts by yeast cells.…”

Developing Organisms for Consolidated Bioprocessing of Biomass to Ethanol

“…The resulting strain produced ethanol at levels comparable with Z. mobilis. Subsequent work has focused on improving ethanol yields, growth rate, strain stability and ethanol tolerance (Ingram et al, 1987;Ohta et al, 1991a;Ingram et al, 1991;Chen et al, 2009;Da Silva et al, 2005a;Yamano et al, 1998). Wild type E. coli strains are incapable of rapid growth on cellobiose (Moniruzzaman et al, 1997).…”