Biocatalytic Production of Oxidized Furan Derivatives from Lignocellulosic Sugar-Rich Streams Using a Novel Fungal Glyoxal Oxidase.

Lignocellulosic biomass is a renewable and abundant resource for producing high-value chemicals as sustainable alternatives to petroleum-derived products. Among these, 5-hydroxymethylfurfural (HMF) and furfural (FA), generated through catalytic dehydration of biomass-derived sugars, serve as pivotal intermediates for enzymatic synthesis of valuable platform chemicals like 2,5-furandicarboxylic acid (FDCA). In recent studies, glyoxal oxidases (GlyOx, EC 1.2.3.15) have emerged as promising candidates for the biotransformation of furan derivatives. This study focused on the recombinant production and characterization of a GlyOx from the medicinal basidiomycete Ganoderma lucidum capable of oxidizing HMF and FA with 51.5% and 23.0% conversion, respectively, after 48 h. Furthermore, the enzyme oxidized HMF derived from hexose-rich wheat straw hydrolysates, leading to 32.4% conversion after 72 h, as well as FA derived from beechwood hemicellulosic hydrolysates, leading to furoic acid with 17.0% conversion after 48 h, marking the first time such enzymatic activity has been demonstrated on furans originating from genuine lignocellulosic biomass sugar streams.