Microbial production of low molecular weight phenolics and aromatics

Lignin-degrading basidiomycetous fungi (Coriolus versicolor and Trametes gallica) and cellulase-producing actinobacteria (Microbacterium sp. and Streptomyces sp.) were used for selective generation of low-molecular weight (LMW) phenolic and aromatic compounds. The kenaf biomass was treated with different combinations of white-rot fungi and bacteria for up to eight weeks. When all strains were used in the pretreatment process, 34% of kenaf biomass was degraded of which 27% was cellulose and 7% was lignin. The glucose yield of 38% peaked on the sixth day of treatment. Incubation of kenaf with T. gallica and Microbacterium sp. for 18 days resulted in production of 26% of xylose yield and 38% of galactose. Once the monosaccharides were depleted, production of laccase, manganese-dependent peroxidase (MnP) and lignin peroxidase (LiP) enzymes, essential for lignin degradation, was induced. Treatment with the basidiomycetous fungi in the absence of actinobacteria produced the highest yield of lignin biodegradation products that contained a mixture LMW, water-soluble phenolics and aromatics. The main products of lignin biodegradation, identified by GC-MS, were veratryl alcohol, and acetovanillone. The former is a raw material for the synthesis of cyclotriveratrylene used in host-guest chemistry, whereas the latter has pharmacological properties and is used in various medical applications.