Monday, August 13, 2012
Columbia Hall, Terrace Level (Washington Hilton)
Pectin-rich biomass such as sugar beet pulp (SBP) and citrus waste contain 15-30% (wt/wt) pectin, a polymer of galacturonic acid. These materials are viable feedstock sources for alternative fuels as they are not used for human consumption and animal feed use is of marginal economic value. In order for these feedstocks to be used, the polymers must be hydrolyzed using enzymes such as pectinase, cellulase and hemicellulase to release monomeric sugar molecules which the ethanologen can ferment. Use of these commercial enzymes increases the price of industrial ethanol production. H. jecorina Rut-C30 was genetically engineered for the production of pectinase enzyme (Pec2) by expressing a polygalacturonase (PG) gene, homologous to the A. niger endopolygalacturonase B (PGB) under the control of the cel7A promoter and terminator. Upon purification of the recombinant PG enzyme (Pec2), the optimal pH and thermal stability was studied by measuring enzyme activity and compared against A. niger polygalacturonase (ANP). The recombinant conidia spores were grown in sugar beet pulp media containing lactose (as inducer of cel7A) and the enzymes produced were characterized. Under similar condition of growth, the recombinant strain of H. jecorina produced large amounts of PG as compared to the wild type strain. Partial saccharification and co-fermentation experiments were conducted employing a genetically engineered ethanologenic bacterium (JP08C) using enzyme cocktails produced by both wild type and recombinant H. jecorina separately. It was observed that fermentations employing recombinant enzyme cocktail produced higher levels of ethanol as compared to that of the wild type strain enzyme cocktail.