Characterization of alkylguaiacol-degrading cytochromes P450 for the biocatalytic valorization of lignin
Upgrading lignin, an underutilized component of biomass, is essential for the sustainability of biorefineries. Biocatalysis has considerable potential for upgrading lignin, but our lack of knowledge of relevant enzymes and pathways has limited its application. Herein, we describe a microbial pathway responsible for catabolizing alkylguaiacols, a major component of several industrial lignin streams. Catabolism is initiated by a cytochrome P450, with related P450s catalyzing the O-demethylation of different lignin-derived guaiacols and subsequent catabolism depending on the substitution pattern of the guaiacol. Importantly, the alkylguaiacol catabolic pathway enables bacterial growth on corn stover lignin produced by reductive catalytic fractionation. Overall, these insights greatly facilitate the engineering of P450s and bacteria to biocatalytically upgrade lignin.