The application of microbes to valorise aromatic compounds derived from the abundant plant biopolymer lignin is a rapidly developing area of research that may ultimately enable viable conversion of this recalcitrant and heterogeneous resource to valuable bio-based chemical products. Starting from the three canonical lignin building blocks that differ in the extent of aromatic ring methoxylation, several common classes of enzymatic reactions occur in the upper pathways of aromatic catabolism to prepare aromatic compounds for assimilation into central carbon metabolism, including aromatic O-demethylation, hydroxylation, and decarboxylation. These critical enzymatic steps can often be rate-limiting for efficient biological funnelling of aromatic compounds. Here we review the known enzymatic mechanisms for these reactions that are relevant for aerobic aromatic catabolism of lignin-related monomers, highlighting opportunities at the intersection of biochemistry, enzyme engineering and metabolic engineering for applications in the expanding field of microbial lignin valorisation.
|Publication status||Published - 25 Feb 2022|