Bioconversion of Guaiacylglycerol-β-guaiacyl ether into vanillin by Burkholderia sp. ISTR5: A genomic and proteomic approach

Abstract

Long-term research on biofuel production from lignocellulose did not progress much due to strong inter-unit linkages in lignin structure. Lignin contains β-O-4 linkage as a major bond (50–60%) between aromatic compounds to form a complex 3D-structure. The present study aims for the characterization of a novel strain Burkholderia sp. ISTR5 (R5) for β-O-4 linkage disintegration. Guaiacylglycerol-β-guaiacyl ether (GGE) was taken as a representative compound for β-O-4 linkage analysis. We showed that the strain R5 completely degraded GGE in 72 h. Further, gas chromatography-mass spectrometry (GC-MS) profile showed that vanillin is one of the highest produced chemicals during the degradation of GGE with small fractions of other metabolites in the reaction mixture. Nuclear Magnetic Resonance (NMR) analysis demonstrated the fragmentation of β-O-4 bonds and the advent of new chemical bonds. In addition to it, the whole genome analysis showed that R5 contains a superior enzyme chassis for the degradation of aromatic compounds. Enzymes such as glutathione-s-transferase, biphenyl dioxygenase, catalase/peroxidase, hydrolases, and dehydrogenases dominated the genome of R5. Proteomics analysis showed 2 glutathione lyase, 1 glutathione-s-transferase, 1 GMC oxidoreductase, 2 FAD binding oxidoreductase and several hydrolases, peroxidases, and transferases were upregulated on GGE. This study showed the capability of R5 to degrade and bioconvert the β-O-4 linkage lignin model compound GGE into vanillin.