Fermentation of sugar cane bagasse hemicellulosic hydrolysate and sugar mixtures to ethanol by recombinant Escherichia coli KO11

摘要: Escherichia coli KO11, carrying the ethanol pathway genes pdc (pyruvate decarboxylase) and adh (alcohol dehydrogenase) from Zymomonas mobilis integrated into its chromosome, has ability to metabolize pentoses hexoses ethanol, both in synthetic medium hemicellulosic hydrolysates. In fermentation of sugar mixtures simulating hemicellulose hydrolysate composition (10.0 g glucose/l 40.0 xylose/l) supplemented with tryptone yeast extract, recombinant bacteria produced 24.58 ethanol/l, equivalent 96.4% maximum theoretical yield. Corn steep powder (CSP), a byproduct corn starch-processing industry, was used replace extract. At concentration 12.5 g/l, it able support glucose (80.0 g/l) yield volumetric productivity comparable those obtained media containing Hemicellulose cane bagasse extract also readily fermented within 48 h, achieved 91.5% conversion efficiency. However, CSP/l took twice as long complete.