Converting lignin to value-added products at high yields provides an avenue for making ethanol biorefineries more profitable while reducing the carbon footprint of products generally derived from petroleum. In this study, corn stover lignin was depolymerized by catalytic transfer hydrogenolysis (CTH) in supercritical ethanol with a Ru/C catalyst. The lignin-derived bio-oil was then sequentially extracted utilizing hexane, petroleum ether, chloroform, and ethyl acetate as solvents in order of less polar to polar, and the subsequent bio-oils were characterized using GPC, GC/MS, and HSQC NMR. Results show that the monomers in the bio-oil fractions contained primarily alkylated phenols, hydrogenated hydroxycinnamic acid derivatives, syringol and guaiacol-type lignins created from reductive cleavages of ether linkages, which were sequentially extracted into groups depending on the solvent polarity. The antimicrobial properties of the bio-oils were screened against Gram-positive (Bacillus subtilis, Lactobacillus amylovorus, and Staphylococcus epidermidis) and Gram-negative (Escherichia coli) bacteria and yeast (Saccharomyces cerevisiae) by examining microbial growth inhibition. Results show that CTH-derived bio-oils inhibited all tested organisms at concentrations less than 3 mg/mL. Total monomer concentration and the presence of specific monomers (i.e., syringyl propane) showed correlations to antimicrobial activity, likely due to cell death or membrane damage. This study provides insights into using sequential extraction to fractionate lignin-derived compounds and correlations between the properties of the extracted compounds and their antimicrobial activity.
|Number of pages||13|
|Journal||ACS Sustainable Chemistry and Engineering|
|State||Published - Dec 21 2020|
Bibliographical noteFunding Information:
The authors acknowledge the National Science Foundation under Cooperative Agreement Nos. 1355438 and 1632854. This work was also supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, Hatch-Multistate project under accession number 1018315. We also thank Kirtley Amos and Seth Debolt for their help with and use of the confocal microscope. In addition, we thank Jameson Hunter and Abisola Olayeye for lab assistance.
© 2020 American Chemical Society.
- Liquid-liquid extraction
ASJC Scopus subject areas
- Chemistry (all)
- Environmental Chemistry
- Chemical Engineering (all)
- Renewable Energy, Sustainability and the Environment