S75: Corynebacterium as a biocatalyst for production of ethanol from biomass sugars

Biomass sugars can be a challenging feedstock for biofuels production.  In the case of the “biochemical” conversion route to biofuels, the biomass sugars produced from the pretreatment and enzymatic hydrolysis of the residual solids contain a mixture of six-carbon and five-carbon sugars along with other compounds that are inhibitory to microorganisms.  The challenge is to maximize sugar production, minimize inhibitor production, and develop organisms that maximize product yield and productivity.  In 2011, the National Renewable Energy Laboratory (NREL), Honda R&D, and the Research Institute of Innovative Technology for the Earth (RITE) entered into a research partnership to develop low-cost fuel ethanol from agricultural residues and other cellulosic feedstocks using Corynebacterium glutamicum.  NREL provided dilute-acid pretreated corn stover (PCS) samples to RITE for initial testing with its organism. As a result of the initial work, NREL prepared a wide range of PCS samples by varying acid loadings (including no acid), pressure, and residence time using a 4-L steam-injected pretreatment reactor. The varying pretreatment conditions produced material with different sugar yields and amounts of potential fermentation inhibitors (acetic acid, furfural, HMF, among others).  RITE enzymatically hydrolyzed the PCS and performed fermentations with its strain.  We will jointly present the rationale behind choosing pretreatment conditions for the RITE strain, pretreatment performance results, and will introduce C. glutamicum as a potential ethanologen, including its performance on the PCS produced by NREL.