Bacterial contamination from lactic acid bacteria (LAB) during fuel ethanol fermentation can lead to costly shutdowns and significant losses in ethanol yields. The industry standard for preventing contamination is to utilize antibiotics, but widespread use of these antibiotics increases the chance of antibiotic-resistant bacterial strains and can persist in downstream coproducts such as distillers’ grains. Since lignin phenolic subunits can confer antimicrobial properties, with potential ionophoric modes of action (i.e. selective inhibition of Gram-positives), this study aims to depolymerize biorefinery lignin oxidatively into a bio-oil with selective antimicrobial properties that can replace antibiotics in fuel ethanol fermentation. Alkali pretreated corn stover lignin was depolymerized using peracetic acid into a bio-oil. The resulting bio-oil was characterized for phenolic content via GPC, GC/MS, and NMR. The antimicrobial activity of the bio-oil was then tested against a variety of commercially sampled LAB, including antibiotic resistant strains, and a commercial fermentation yeast strain. The bio-oil was also tested against both α-amylase and glucoamylase for inhibition, prior to performing model simultaneous saccharification and fermentation (SSF) experiments. The model fermentations used corn starch as a feedstock with and without varying levels of LAB contamination, to determine the bio-oils effects on ethanol production. The results obtained from this study offer a new application in lignin valorization and a better understanding of lignin-based bio-oil’s antimicrobial properties/potential.

Controlling fuel ethanol fermentation contaminates using peracetic acid depolymerized biorefinery lignin

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.