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United States Department of Agriculture

Agricultural Research Service

Research Project: ADVANCED CONVERSION TECHNOLOGIES FOR SUGARS AND BIOFUELS: SUPERIOR FEEDSTOCKS, PRETREATMENTS, INHIBITOR REMOVAL, AND ENZYMES

Location: Bioenergy Research Unit

Title: Biological abatement of cellulase inhibitors

Authors
item Cao, Guangli -
item Ximenes, Eduardo -
item Nichols, Nancy
item Zhang, Leyu -
item Ladisch, Michael -

Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 24, 2013
Publication Date: N/A

Interpretive Summary: This study identified a way to improve the activity of enzymes in the biomass-to-biofuels process. Because enzymes are a significant cost in making renewable fuels and chemicals from biomass, increasing activity of enzymes in the process has potential to decrease the cost of the product. In making renewable fuels and chemicals, cellulose is converted to glucose by enzymes termed cellulases. Typically, the activity of cellulase enzymes is decreased by inhibitors present in biomass slurries. We used a microbe that metabolizes inhibitors; this removed the inhibitors, allowing increased enzyme activity and improving conversion of cellulose 1.2- to 1.5-fold. These results will benefit producers of renewable fuels and chemicals.

Technical Abstract: Bio-abatement uses a fungus to metabolize and remove fermentation inhibitors. To determine whether bio-abatement could alleviate enzyme inhibitor effects observed in biomass liquors after pretreatment, corn stover at 10% (w/v) solids was pretreated with either dilute acid or liquid hot water. The pretreated liquors were subjected to bio-abatement, followed by enzymatic hydrolysis of cellulose. To distinguish between inhibitor effects on enzymes and substrate recalcitrance remaining after the two pretreatment methods, pretreated corn stover solids were removed and replaced with 1% (w/v) Solka Floc. Cellulose conversion in the presence of bio-abated liquors from dilute acid pretreatment was 8.6 (0.1x enzyme) and 16% (1x enzyme) higher than control (non-abated samples). In the presence of bio-abated liquor from liquid hot water pretreated corn stover, 10% (0.1x enzyme) and 13% (1x enzyme) higher cellulose conversion was obtained compared to control. Biological inhibitor abatement yielded improvement in enzyme hydrolysis in the same range as that obtained using a chemical (overliming) method for mitigating inhibitors.

Last Modified: 10/21/2014
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