The Laccase Catalysed Tandem Lignin Depolymerisation/Polymerisation

Abstract

The development of strategies allowing either the production of high value phenolics, or the isolation of properties‐enhanced materials from technical lignins represents a fundamental step in the industrial upcycling of technical lignins. Both aims are met by the strategy presented in the present work, relying on the coupling of solvent‐based fractionation with the oxidative action of a new type of alkaline‐stable transgenic laccase. The described approach succeeded in the tandem, high‐yield and selective isolation of valuable lignin‐monomeric compounds (MCs) and high molecular weight and hydrophobicity‐tailored polymerised materials (PMs) from two technical lignins, namely softwood kraft lignin (SKL), and wheat straw organosolv lignin (WSL). Noteworthy, the reaction conditions were optimized for the selective production of single MCs. Most interestingly, technical lignins as well as their fractions and the PMs deriving from their laccase‐catalysed oxidation showed increased hydrophobicity.