Development of the production of 2-pyrone-4,6-dicarboxylic acid from lignin extracts, which are industrially formed as by-products, as raw materials.

Lignosulfonate is a by-product of the cooking process by sulfite pulping for paper manufacturing. The treatment of wood chips by various salts of sulfurous acid solubilizes lignin to produce a cellulose-rich wood pulp. Developing a technique for the conversion of lignosulfonate by-product to high value materials has an important industrial utility. Sphingobium sp. strain SYK-6, which was isolated from pulping wastewater, is one of the best enzymatically or genetically characterized bacteria for degrading lignin-derived aromatics. We have previously established a system for the production of 2-pyrone-4,6-dicarboxylic acid (PDC), a novel platform chemical that can produce a variety of bio-based polymers, by introducing of ligA, ligB, and ligC genes from SYK-6 into a mutant strain of Pseudomonas putida PpY1100. In this study, extracts from lignosulfonates, which were desulphonated and depolymerized by alkaline oxidation, were evaluated as substrates for microbiological conversion to PDC by the transgenic bacteria.