Lignin is the most abundant renewable phenolic polymer in nature, therefore its effective utilization is desirable. In particular, microbial conversion known as “biological funneling” is attracting great attention as a practical way to produce platform chemicals such as 2-pyrone-4,6-dicarboxylic acid (PDC) from lignin [1]. In this study, we developed a gene-modified bacterial fermentation system for production of PDC from various low-molecular-weight aromatic compounds generating by chemical treatment of lignin.
The alphaproteobacterium Sphingobium sp. strain SYK-6 is able to grow on lignin-derived biaryls and monoaryls using a number of specific enzymes [2, 3]. Gene coding for the metabolic enzymes that act on aromatic compounds from SYK-6, were inserted into a broad host-range plasmid vector pKT230MC. The resulting plasmid pKTVPVABC was introduced into Pseudomonas putida strain PpY1100. Gene-modified PpY1100 reliably produced and accumulated PDC from various lignin-derived monoaryls including vanillin, vanillic acid, syringaldehyde, and syringic acid. Furthermore, using PDC as a raw material, we developed an antibacterial agent via the formation of PDC-Ag+ complex, and also novel PDC-based polymers similar to those that can be derived from petrochemicals [4]. In the future, we expect to establish a sustainable society through the utilization of PDC as a platform chemical derived from lignin.