A systematic bioprocessing approach for the co-production of ethanol and succinic acid from lignocellulosic feedstock using novel yeast strains

Abstract

Saccharomyces cerevisiae consumes Glucose present in lignocellulosic biomass and converts it into ethanol. However, the utilization of five-carbon sugars, like xylose, would result in a 40% increase in product yield compared to utilizing Glucose alone. Much research has already been done on utilizing xylose by integrating xylose dehydrogenase and xylose reductase genes into the saccharomyces genome. However, product yield was lower compared to when utilizing Glucose alone. Several bottlenecks are identified using genome-scale dynamic flux balance analysis of metabolic pathways limiting ethanol production when grown on xylose and Glucose. Most recent studies showed this is due to the imbalance in reducing equivalents produced in respiratory pathways. Our project aims at modifying Saccharomyces cerevisiae by integrating a set of five genes regulating the respiratory pathways of the organism to produce ethanol as well as succinate in significantly large amounts and to develop a systematic bioprocessing an approach that is technically feasible, economically viable, and environmentally low impact in a biorefinery level, which would result in producing more than 200g/L sugar titers after enzymatic hydrolysis and having more than 90% xylose consumption the efficiency of five- and six-carbon sugars and converting them into succinate and ethanol with an efficiency of more than 90%. This would result in about a 40% decrease in product cost. Keywords: Saccharomyces cerevisiae, dynamic Flux balance analysis, ethanol, succinate.