ISOLATION AND CHARACTERIZATION OF ETHANOL-TOLERANT MUTANTS OF ESCHERICHIA-COLI KO11 FOR FUEL ETHANOL-PRODUCTION

Genetically engineered Escherichia coli KO11 is capable of efficiently producing ethanol from all sugar constituents of lignocellulose but l acks the high ethanol tolerance of yeasts currently used for commercia l starch-based ethanol processes. Using an enrichment method which sel ects alternatively for ethanol tolerance during growth in broth and fo r ethanol production on solid medium, mutants of KO11 with increased e thanol tolerance were isolated which can produce more than 60 g ethano l L-1 from xylose in 72 h, Ethanol concentrations and yields achieved by the LYO1 mutant with xylose exceed those reported for recombinant s trains of Saccharomyces and Zymomonas mobilis, both of which have a hi gh native ethanol tolerance.