Issue 1, 2023

Elucidation of microbial lignin degradation pathways using synthetic isotope-labelled lignin

Abstract

Pathways by which the biopolymer lignin is broken down by soil microbes could be used to engineer new biocatalytic routes from lignin to renewable chemicals, but are currently not fully understood. In order to probe these pathways, we have prepared synthetic lignins containing 13C at the sidechain β-carbon. Feeding of [β-13C]-labelled DHP lignin to Rhodococcus jostii RHA1 has led to the incorporation of 13C label into metabolites oxalic acid, 4-hydroxyphenylacetic acid, and 4-hydroxy-3-methoxyphenylacetic acid, confirming that they are derived from lignin breakdown. We have identified a glycolate oxidase enzyme in Rhodococcus jostii RHA1 which is able to oxidise glycolaldehyde via glycolic acid to oxalic acid, thereby identifying a pathway for the formation of oxalic acid. R. jostii glycolate oxidase also catalyses the conversion of 4-hydroxyphenylacetic acid to 4-hydroxybenzoylformic acid, identifying another possible pathway to 4-hydroxybenzoylformic acid. Formation of labelled oxalic acid was also observed from [β-13C]-polyferulic acid, which provides experimental evidence in favour of a radical mechanism for α,β-bond cleavage of β-aryl ether units.

Graphical abstract: Elucidation of microbial lignin degradation pathways using synthetic isotope-labelled lignin

Supplementary files

Article information

Article type
Paper
Submitted
28 7 2022
Accepted
20 11 2022
First published
24 11 2022
This article is Open Access
Creative Commons BY license

RSC Chem. Biol., 2023,4, 47-55

Elucidation of microbial lignin degradation pathways using synthetic isotope-labelled lignin

A. Alruwaili, G. M. M. Rashid, V. Sodré, J. Mason, Z. Rehman, A. K. Menakath, D. Cheung, S. P. Brown and T. D. H. Bugg, RSC Chem. Biol., 2023, 4, 47 DOI: 10.1039/D2CB00173J

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