The role of fungal transcriptome analysis and side-chain hydrolyzing enzymes in sugarcane bagasse breakdown

Abstract

Lignocellulose represents one of the main sources of renewable energy for biofuel production. Within this context, sugarcane bagasse, which is a discarded by-product of sugarcane processing, is a rich source of lignin, hemicellulose, and cellulose. Since sugarcane bagasse is a complex lignocellulosic structure, its complete enzymatic hydrolysis requires the action of an enzyme system of main- and side-chain enzymes. The xylan component in sugarcane bagasse is arabinosylated at positions C-2 and/or C-3 and esterified with ferulic acid at the C-5 position. Accessory enzymes such as α-arabinofuranosidase and feruloyl esterase are responsible for enhanced accessibility and enzymatic hydrolysis of xylan. Under industrial conditions, numerous filamentous fungi can secrete enzymes or enzyme complexes belonging to the glycosyl hydrolases, carbohydrate esterases, and polysaccharide lyases for the hydrolysis of cellulose, hemicellulose, and lignin. Next-generation sequencing approaches for whole-genome and transcriptome analyses enable the identification of novel genes and isoforms in fungi encoding hydrolytic enzymes, thus increasing our understanding of mechanisms involved in gene expression induction in the presence of plant cell wall or its metabolic products. The downstream application will accelerate strain improvement for increased enzymatic efficiencies and hydrolytic enzyme cocktail development, contributing to reducing cellulosic bioethanol production costs.