Bioconversion of wheat straw lignocellulosic sugars to ethanol by recombinant Escherichia coli

Recombinant microorganisms are a promising alternative for production of bioethanol from sugars produced from lignocellulosic materials. In the present work, recombinant Escherichia coli FBR16 has been utilized to produce bioethanol from simulated glucose-xylose mixtures and wheat straw hydrolysates. Hydrolysates were produced by sequential treatment of dilute acid pretreatment at 180 °C for 7 min using 0.5% (v/v) H2SO4 and enzymatic saccharification using cellulase from Trichoderma reesei and β-glucosidase from Aspergillus niger. With increased concentration of glucose-xylose sugar mixtures, ethanol yield and volumetric ethanol productivity decreased. At 22 g/l, ethanol yield of 0.34 g/g and volumetric ethanol productivity of 0.36 g/l·h were obtained which reduced to only 0.19 g/g and 0.17 g/l·h, respectively, at 160 g/l glucose-xylose sugar mixture. Fermentation kinetic parameters were also estimated and it was found that values of parameters were highly dependent on initial sugar concentration. Further...