GENOMICS AND ENGINEERING OF STRESS-TOLERANT MICROBES FOR LOWER COST PRODUCTION OF BIOFUELS AND BIOPRODUCTS
Location: Crop Bioprotection Research
Title: THE ROLE OF THE PENTOSE PHOSPHATE PATHWAY IN FERMENTATION INHIBITOR TOLERANCE
Submitted to: Biotechnology for Fuels and Chemicals Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 4, 2005
Publication Date: May 6, 2005
Citation: Gorsich, S.W., Liu, Z., Slininger, P.J. 2005. The role of the pentose phosphate pathway in fermentation inhibitor tolerance. Biotechnology for Fuels and Chemicals Symposium Proceedings. Abstract No. 5-33.
Acid hydrolysis pretreatment of lignocellulose biomass releases sugars (glucose, xylose, etc.) for industrial ethanol fermentation. During fermentation, degradation products of xylose and glucose can form inhibitory products, furfural and 5-hydroxymethylfurfural (HMF), respectively. At high concentrations these inhibitors inhibit cell growth and reduce ethanol yield. Engineering yeast to be more tolerant of these inhibitors will lead to a more efficient lignocellulose to ethanol bioconversion. Recently, the pentose phosphate pathway (PPP) was implicated in furfural, HMF, and ethanol tolerance. The PPP contains nine genes, ZWF1, GND1, GND2, RPE1, RKI1, TKL1, TKL2, TAL1, and YGR043C (TAL2). Strains lacking ZWF1, GND1, RPE1, or TKL1 have severe growth defects in the presence of furfural. In the presence of HMF or ethanol, these mutants have noticeable growth defects but less severe compared to furfural. These mutants are further characterized in regards to their effects on cellular physiology. In addition, the individual effect of overexpression of all nine PPP genes is also characterized in regards to growth, inhibitor tolerance, and ethanol yield using both standard lab medium and lignocellulosic derived medium.