Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 4/11/2002
Publication Date: 4/11/2002
Citation: DIEN, B.S., BOTHAST, R.J., NICHOLS, N.N., SKORY, C.D. IMPROVED BIOCATALYST FOR PRODUCTION OF BIOETHANOL AND LACTIC ACID. AMERICAN CHEMICAL SOCIETY. 2002. ABSTRACT NO. 322.
Technical Abstract: There is a need for improved biocatalyst for converting biomass into fuels and chemicals. We have constructed several strains for production of ethanol and lactic acid. Conversion of lignocellulosic biomass requires strains capable of fermenting sugar mixtures that contain pentoses. We have developed several recombinant Escherichia coli strains that will convert sugar mixtures to either ethanol or lactate with metabolic yields that are 90-93% of theoretical. The strains carry the genes needed for conversion of pyruvate to either ethanol or lactic acid on a plasmid. Retention of the plasmid is selected for when the strains are growing fermentatively because of the genetic background of the strains. New strains have also been constructed that carry a glucose phosphotransferase mutation (ptsG), which allows for simultaneous utilization of glucose and pentoses, such as xylose. Presence of the ptsG mutation improved the final llactic acid yield from a glucose and xylose mixture by 54% compared to the non-ptsG control strain because of improved fermentation of the xylose. One of the microorganisms used for industrial production of lactic acid is the fungi Rhizopus oryzae. We have cloned an ldh gene from R. oryzae and developed genetic transformation methods for stable chromosomal integration. Recombinant strains had increased LDH activity and produced 30% more lactic acid than parental wild type.