Mary Ann Franden, Heidi M. Pilath, Ali Mohagheghi, Phil T. Pienkos, and Min Zhang. National Bioenergy Center, NREL, 1617 Cole Blvd, MS3323, Golden, CO 80401
During the pretreatment, hydrolysis, and subsequent conditioning of biomass feedstocks, many toxic compounds are produced or introduced which subsequently inhibit microbial growth and in many cases, production of ethanol. An understanding of the toxic effects of compounds found in hydrolysate is critical to improving ethanol yields in the fermentation process. Since cell growth is strongly related to ethanol production for many inhibitory compounds, growth rate measurements in the presence of toxic compounds can be a useful tool for surveying hydrolysate toxicity. In this study, we examined the effects of selected aldehydes, organic and inorganic acids (along with various cations), and alcohols on growth of Zymomonas mobilis 8b in glucose and xylose. In addition, synergistic effects among the most dominant inhibitors were also examined. An understanding of toxicity contributed by individual compounds provides critical information for biomass to ethanol process improvements.
