Metagenomic insights into mangrove lignocellulolytic bacteria and functional analysis of a glucose-tolerant GH 1 β-glucosidase

Abstract Mangrove ecosystems contain abundant lignocellulosic biomass and mangrove microorganisms that are capable of degrading plant polymers. In this study, a shotgun metagenomic approach was employed to explore the bacterial communities from Tanjung Piai National Park, Malaysia and their genes involved in lignocellulosic biomass degradation. A total of 148 of carbohydrate active enzymes (CAZy) genes spanning GH, CE, and AA families were identified with lignocellulolytic abilities. These enzymes included 20 cellulases, 46 hemicellulases, and 82 lignin-modifying enzymes. Approximately 89. 19% of these genes were found from underexplored bacterial lineages. A set of lignocellulolytic genes derived from diverse bacterial taxa highlighted the synergistic action of mangrove bacteria in lignocellulose degradation. To validate the functionality of these genetic resources, one of the genes (BGL3GH1) encoding a β-glucosidase was selected for expression and characterisation. The recombinant enzyme showed optimal activity at 60 ℃ and pH 7, retained up to 75% activity at 10% (w/v) NaCl. The enzyme exhibited a 1. 6 to 2. 1-fold in enzyme activity with glucose concentration up to 2 M. In a two-step saccharification assay using sugarcane bagasse, supplementation with recombinant BGL3GH1 enhanced the saccharification yield (0. 0674 g g − 1 biomass) compared with treatments using commercial cellulase or recombinant BGL3GH1 alone. These findings reveal the functional diversity of lignocellulose-degrading genes in mangrove bacteria and identify recombinant BGL3GH1 as a potential enzyme candidate for biomass conversion application.