Technical Abstract: United States fuel ethanol production in 1998 exceeded the record production of 1.4 billion gallons set in 1995. Most of this ethanol was produced from over 550 million bushels of corn. Expanding fuel ethanol production will require developing lower cost feedstocks, and only lignocellulosic feedstocks are available in sufficient quantities to substitute for corn starch. A major technical hurdle to converting lignocellulose to ethanol is developing an appropriate microorganism for the fermentation of mixed sugars. The most successful research approaches to develop novel biocatalysts that will efficiently ferment mixed sugar syrups include isolation of novel yeasts that ferment xylose, genetic engineering of Escherichia coli and other gram negative hosts for ethanol production, and genetic engineering of Saccharomyces cerevisiae and Zymomonas mobilis for pentose utilization. We objectively evaluated the fermentation of corn fiber hydrolyzates by the strains made available to us. E. coli K011, E. coli SL40, FBR3, Zymomonas CP4(pZB5), and Saccharomyces 1400 (pLNH32) fermented corn fiber hydrolyzates to ethanol in the range of 21-34 g/liter with yields ranging from .41 to .50 g ethanol per g sugar consumed. Each research approach holds considerable promise, with the possibility existing that mature strains of each recombinant may be suitable for commercial ethanol production.