Sunday, May 3, 2009
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Engineering of yeast strains capable of broad substrate utilization in alcohol fermentation - Part I: Identification of founder strains and gene candidates
Pushpa Gujjari, Janice Houseknecht, Sung-Oui Suh, and Jim Zhou. Mycology, ATCC (American Type Culture Collection), 10801 University Blvd, Manassas, VA 20110
Alcohols such as ethanol and butanol produced directly from renewable biomass are considered as an important alternative energy source for sustainable development of human society. Conversion of low-value biomass and industrial organic waste into alcohols, however, has remained a significant challenge due to rarity of natural organisms able to do so and the performance limitation of existing engineered microbes. Working with a collection of over 400 biomass-utilizing or alcohol-producing fungi/yeast strains, we have begun a two-pronged approach to address the need for alternative energy sources: 1) isolation and characterization of natural fungi able to ferment lignocellulose to alcohols and 2) genetic engineering of high alcohol-producing yeast strains capable of using a wide-range of biomass and organic waste. Here we report the progress on selection of stress tolerant founder strains, selection of desired genes or gene clusters from Trichoderma reesei, strategy of strain construction, and characterization of resultant yeast strains that are able to digest pretreated woody materials and ferment them into alcohols. A single organism capable of simultaneous saccharification of biomass and fermentation of alcohols (SSF) has the advantage of simplified industrial process and reduced production cost.