The Catabolism of Lignin-Derived p-Methoxylated Aromatic Compounds by Rhodococcus jostii RHA1: Article No. e02155-23

Megan Wolf, Anne Lalande, Brianne Newman, Alissa Bleem, Chad Palumbo, Gregg Beckham, Lindsay Eltis

Research output: Contribution to journalArticlepeer-review

Abstract

Emergent strategies to valorize lignin, an abundant but underutilized aromatic biopolymer, include tandem processes that integrate chemical depolymerization and biological catalysis. To date, aromatic monomers from C-O bond cleavage of lignin have been converted to bioproducts, but the presence of recalcitrant C-C bonds in lignin limits the product yield. A promising chemocatalytic strategy that overcomes this limitation involves phenol methyl protection and autoxidation. Incorporating this into a tandem process requires microbial cell factories able to transform the p-methoxylated products in the resulting methylated lignin stream. In this study, we assessed the ability of Rhodococcus jostii RHA1 to catabolize the major aromatic products in a methylated lignin stream and elucidated the pathways responsible for this catabolism. RHA1 grew on a methylated pine lignin stream, catabolizing the major aromatic monomers: p-methoxybenzoate (p-MBA), veratrate, and veratraldehyde. Bioinformatic analyses suggested that a cytochrome P450, PbdA, and its cognate reductase, PbdB, are involved in p-MBA catabolism. Gene deletion studies established that both pbdA and pbdB are essential for growth on p-MBA and several derivatives. Furthermore, a deletion mutant of a candidate p-hydroxybenzoate (p-HBA) hydroxylase, ..delta..pobA, did not grow on p-HBA. Veratraldehyde and veratrate catabolism required both vanillin dehydrogenase (Vdh) and vanillate O-demethylase (VanAB), revealing previously unknown roles of these enzymes. Finally, a ..delta..pcaL strain grew on neither p-MBA nor veratrate, indicating they are catabolized through the ..beta..-ketoadipate pathway. This study expands our understanding of the bacterial catabolism of aromatic compounds and facilitates the development of biocatalysts for lignin valorization.
Original languageAmerican English
Number of pages18
JournalApplied and Environmental Microbiology
Volume90
Issue number3
DOIs
StatePublished - 2024

NREL Publication Number

  • NREL/JA-2A00-88294

Keywords

  • aromatic biopolymers
  • biological catalysis
  • c-c bond cleavage
  • chemical depolymerization
  • lignin valorization

Fingerprint

Dive into the research topics of 'The Catabolism of Lignin-Derived p-Methoxylated Aromatic Compounds by Rhodococcus jostii RHA1: Article No. e02155-23'. Together they form a unique fingerprint.

Cite this