Recombinant Microorganisms That Catabolize Lignin Aromatics and Methods of Using Same

UW-Madison researchers have identified enzymes that are necessary and sufficient for the catabolism of the β-5 linked aromatic dimer dehydrodiconiferyl alcohol (DCA) by Novo. The first newly identified enzyme, γ-formaldehyde lyase (PcfL), opens the phenylcoumaran ring to generate a stilbene and formaldehyde. The second newly identified enzyme, lignostilbene dioxygenase (LsdD), cleaves the stilbene to generate the aromatic monomers vanillin and 5-formylferulate. In addition, the inventors found that a previously identified aldehyde dehydrogenase, FerD, oxidizes 5-formyl ferulate before it is decarboxylated by LigW to ferulic acid. This is a newly reported activity of FerD, which adds an additional route for producing vanillin/vanillic acid from DCA. When coupled with the researchers’ previously disclosed enzymes, the vanillin and vanillic acid intermediates are converted to PDC, which can be enzymatically converted to desirable end products.