Oral Presentation 2-02

Improving Klebsiella oxytoca for Ethanol Production from Cellulosic Biomass

Brent E. Wood* and Lonnie O. Ingram

Department of Microbiology and Cell Science,

University of Florida, Gainesville, FL  32611

Phone: (352) 392-5924

Fax: (352)846-0969

E-mail: brentw@biotech.ufl.org

In the microbial conversion of cellulosic biomass to commodity chemicals, such as ethanol, the cost of nutrients and fermentation efficiency have significant impacts on process economics. Using the previously described ethanologenic bacterium, Klebsiella oxytoca P2, a CSL-Urea based fermentation medium was developed for the conversion of the major sugar constituents of cellulosic biomass. During this work it was found that, under conditions that are optimal for the use of fungal cellulases (pH 5.0-5.5), a significant amount of carbon (14-15%) was fermented to 2,3-butanediol. Two genes from the butandiol pathway, encoding acetolactate decarboxylase (budA) and acetolactate synthase (budB), were cloned and used to construct “knockout” mutants devoid of these functional genes. The new strain, BW19, produced ethanol at higher yields than the parent strain P2. Continuing studies include the elimination of other co-product pathways, improving fermentations of sugar mixtures, and use of CSL-Urea medium during SSF.