Bioconversion of Organosolv Lignin by Rumen Bacterium: Isolation, Characterization and Metabolic Profiling

TL;DR

This study isolates a rumen bacterium that can break down lignin, a byproduct of the paper and biorefining industries, into valuable aromatic compounds.

Contribution

The isolation and characterization of Klebsiella sp. IL2_9 for anaerobic lignin degradation and aromatic compound production is novel.

Findings

Klebsiella sp. IL2_9 removed 22% of organosolv lignin within 24 hours.

FTIR and GC–MS analyses confirmed structural changes and the formation of aromatic metabolites like vanillyl alcohol and phenyllactic acid.

Abstract

Residual lignin generated by pulp, paper, and biorefining industries is commonly burned for energy, despite its potential as a renewable source of aromatic compounds. Studies focusing on microbial lignin degradation contribute to lignin valorization and represent a sustainable strategy to enhance biomass circularity. Here, we report the isolation of Klebsiella sp. IL2_9 from a ruminal consortium and demonstrate its ability to degrade and metabolize organosolv lignin. After 24 h of cultivation, the strain removed 22% of the initial lignin content. FTIR analysis revealed alterations in functional groups associated with guaiacyl and syringyl units, indicating structural modification of the polymer. GC–MS analyses further showed the consumption of lignin-derived aromatics, including vanillin, 2-aminobenzoic acid, and 4-hydroxybenzoic acid, along with the formation of vanillyl alcohol and phenyllactic acid derivatives. Overall, these findings highlight the potential of Klebsiella sp. IL2_9 as a promising biotechnological candidate for lignin valorization under anaerobic conditions.

Figures