Butanol is a valuable chemical that can be used for the production of solvents, plasticizers, butylamines and amino resins. Butanol is also a drop-in fuel, which can easily be blended with gasoline or upgraded to advanced biofuels such as jet fuel. Butanol has been produced by the traditional acetone-butanol-ethanol (ABE) fermentation using molasses, starches and lignocellulosic biomass. Unfortunately, the yield of butanol from biomass (e.g. glucose, xylose, starch) conversion is poor.
Butanol fermentation from lignocellulosic biomass is limited due to butanol toxicity to microbial cells. Hence, there is a critical need to develop new technologies to alleviate butanol toxicity to fermenting microbes during fermentation and improve butanol yield. Dr. Hasan Atiyeh, Professor of Biosystems and Agricultural Engineering at Oklahoma State University (OSU), Stillwater, OK, collaborated with Dr. Thaddeus Ezeji from the Department of Animal Sciences, The Ohio State University, to develop a way to increase butanol yield and improve the economics of production via the integrated novel conversion process and utilization of lignocellulosic biomass and CO2.
Atiyeh’s research team successfully developed lignocellulose-derived microbial inhibitory compounds (LDMIC)-tolerant bacterial strains, Clostridium beijerinckii (Cb) and C. carboxidivorans (Cc), which grew in the presence of LDMICs and converted sugars and CO2 and H2 from switchgrass to ABE.
“We innovatively incorporated the butanol producing bacterial strains in a two-stage continuous stirred tank reactor (CSTR) system, with a Cb strain fermenting lignocellulose-derived sugars to butanol, CO2 and H2 in the first reactor, and a Cc strain converting the CO2 and H2 produced in the first reactor to butanol in the second stage,” Atiyeh said.
“Our technology improved ABE fermentation by over 20% using a short chain dehydrogenase reductase Cb strain. ABE fermentation medium cost was reduced by over 80% and ABE production was enhanced by 86% with the use of biochar compared to typical ABE fermentation medium,” Atiyeh added. “We expect that the use of biochar could be an economical strategy for large scale ABE production.”
This project will provide valuable information for the development of a viable technology for drop-in fuel production and for sustainable biorefineries expansion based on the biochemical conversion process with increased yields.
Funding of this project was provided by the U.S. Department of Agriculture-National Institute of Food and Agriculture (USDA-NIFA) through the South Central Sun Grant Program.