M85
Characterization of water-soluble lignin extractives from Extractive Ammonia (EA) pretreatment and their effects on yeast fermentation using synthetic biomass hydrolysate
Monday, April 25, 2016
Key Ballroom, 2nd fl (Hilton Baltimore)
S. Xue*, M. Jin, C. Sarks and V. Balan, DOE Great Lakes Bioenergy Research Center, Lansing, MI, USA; L.D.C. Sousa, Department of Chemical Engineering and Materials Science, Michigan State University, Lansing, MI, USA; J. Piotrowski, University of Wisconsin-Madison, Madison, WI, USA; A.D. Jones, Michigan State University, East Lansing, MI, USA; B. Dale, DOE Great Lakes Bioenergy Research Center, Michigan State University, Lansing, MI, USA
The DOE Great Lakes Bioenergy Research Center (GLBRC) has formulated a chemically-defined synthetic hydrolysate (SynH) to mimic real AFEX
TM corn-stover hydrolysate (ACSH). The SynH is based on the chemical composition of real hydrolysate and has proven useful in studying the inhibitory effects of degradation products generated during pretreatment. Extractive-Ammonia (EA) is a newly developed pretreatment technology that selectively extracts lignin present in biomass. Compared to AFEX, EA generates a separate lignin extractive stream and removes most of the degradation products. Thus, EA-pretreated corn-stover (EA-CS) was found to have reduced lignin content, and is also highly digestible during enzyme hydrolysis and very fermentable.
Herein, we use SynH to study the inhibition of yeast fermentation by water-soluble lignin extractives (LEs) isolated from EA extractives. We found that SynH with 20g/L LEs mimics real hydrolysate in cell growth, sugar consumption and ethanol production. Nevertheless, a long lag phase was observed in the first 48 hrs, indicating that additional inhibitors were produced during EA pretreatment. Ethyl-acetate extraction was used to separate phenolic compounds from water-soluble LEs. These nitrogenous/phenolic compounds were characterized and quantified using LC/GC-MS. Some of the compounds identified in LEs include coumaroyl/feruloyl amide and coumaroyl glycerol. These and other water-soluble degradation compounds act as key inhibitors to yeast fermentation, while the nutrients in the water phase after ethyl acetate separation actually enhance ethanol production. Chemical genomics was employed to see the fingerprints of genes deletion response to inhibitors. The different sensitive/resistant genes clusters confirmed the variability of inhibitors in LE with ACSH.
