Submitted to: Bioresource Technology
Publication Type: Abstract Only
Publication Acceptance Date: August 26, 1999
Publication Date: N/A
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. Major technical hurdles to converting lignocellulose to ethanol include lack of low cost efficient enzymes for saccharification of biomass to fermentable sugars and development of microorganisms for the fermentation of these mixed sugars. To date, 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 bacteria, and genetic engineering of Saccharomyces cerevisiae and Zymomonas mobilis for pentose utilization. We have evaluated the fermentation of corn fiber hydrolyzates by the various strains developed. E. coli KO11, E. coli SL40, E. coli 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 find a separate application in the fermentation of specific feedstocks.