Bioprospecting Fungal Glycosyl Hydrolases: Multi-locus Phylogenetic Analysis and Enzyme Activity Profiling for Enhanced Biomass Valorization

Abstract Lignocelluloses comprise of celluloses and hemicelluloses which can be effectively depolymerized to obtain fermentable sugars using diverse microbial enzymes, for subsequent conversion to various value-added products. Present study reports the bioprospecting of industrially significant microorganisms and their characterization to attain xylanases with high catalytic efficiency. Four potential xylanolytic fungi were identified through distinct primary and secondary screening process of 294 isolates from samples containing plant degrades. Morphological characterization and multigene analysis (ITS rDNA, 18S rDNA, nLSU rDNA, β-tubulin and actin gene) confirmed them Aspergillus niger AUMS56, Aspergillus tubingensis AUMS60, Aspergillus niger AUMS64 and Aspergillus fumigatus AUKEMS24 and their crude xylanase activities through submerged fermentation using corncob were 18.9, 32.29, 30.68 and 15.82 U ml-1, respectively. AUMS60 and AUMS64 have highest catalytic activity of 1429 U g-1 and 1243 U g-1, respectively, all having pH and temperature optima of 6.0 and 60°C respectively, where AUMS60 produced single xylanase (Xyn60; 36 kDa) and AUMS64 secreted 2 probable isozymes (Xyn64A and Xyn64B; 33.4 and 19.8 kDa). Maximum saccharification efficiency of AUMS60 and AUMS64 were 51.1% (13 h) and 52.2% (24 h) showing enhanced catalytic activity with various cations. Present research reports potential xylanases from indigenous fungi, providing opportunity for development of bio-catalysts concoction (novelty established) for enhanced saccharification of complex lignocelluloses finding specific industrial applications for production of value-added components.