mannanases

Mannanases are enzymes that catalyze the cleavage of β-1,4-mannosidic linkages in mannans, which are major hemicellulose components of plant cell walls. They primarily act on galactomannans such as guar gum and locust bean gum. The class includes endo-β-1,4-mannanases that cleave internal linkages to produce shorter mannooligosaccharides, and exo-acting β-mannosidases that release mannose from chain ends. Together they contribute to the degradation of mannans in microbial and plant environments.

Source and structure: Mannanases are produced by fungi (Aspergillus, Trichoderma), bacteria (Bacillus, Streptomyces), and to a lesser extent yeasts. Many are secreted extracellular enzymes and are modular, often with carbohydrate-binding modules that help bind insoluble substrates. They belong to several glycoside hydrolase families, notably GH5, GH26, and GH113, reflecting diverse catalytic strategies and substrate ranges. Optima vary by enzyme; fungal enzymes often prefer acidic to neutral pH and moderate to high temperatures, with some thermostable variants.

Applications: In industry, mannanases are used to improve paper pulp bleaching, enhance extraction and clarification in coffee and juice production, and improve digestibility of plant-based feeds. They are employed in conversion of lignocellulosic biomass for biofuels and bioproducts, often as part of enzyme cocktails with other hemicellulases and cellulases. Ongoing research seeks to tailor substrate specificity, stability, and activity for sustainable processing and economic production.