First generation bioethanol production utilizes the starch fraction of maize, which accounts for approximately 60% of the ash-free dry weight of the grain. Scale-up of this technology for fuels applications has resulted in a massive supply of distillers dried grains with solubles (DDGS) coproduct, which is rich in cellulosic polysaccharides and protein. It was surmised that DDGS would be rapidly adopted for animal feed applications, however, this has not been observed based on inconsistency of the product stream and other logistics-related risks, especially toxigenic contaminants. Therefore, efficient valorization of DDGS in for production of petroleum displacing products will significantly improve the technoeconomic feasibility and net energy return of the established starch bioethanol process. In this study, we demonstrated “one-pot” bioconversion of the protein and carbohydrate fractions of a DDGS hydrolysate into C4 and C5 fusel alcohols through development of a microbial consortium incorporating two engineered Escherichia coli bioconversion strains. In the engineered coculture system, one E. coli strain was modified for efficient conversion of the glucose and xylose in the DDGS hydrolysates to isobutanol. The other E. coli strain was modified for efficient utilization of the proteins in the DDGS hydrolysates to produce mixed C4 and C5 alcohols. The inoculation ratio between the two E. coli strains in the coculture system was optimized and near theoretical yield of the mixed alcohols was achieved. We have also recently demonstrated that the engineered E. coli coculture system is similarly applicable for biofuel production from other biomass sources, including micro- and benthic algae hydrolysates.

One-pot bioconversion of distiller dried gains hydrolysate to advanced biofuels

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.