Mannanase is a naturally occurring enzyme that breaks down complex carbohydrates. It targets mannans, which are polysaccharides composed of mannose units. As a glycoside hydrolase, mannanase cleaves the β-1,4-mannosidic bonds within these structures. This action effectively breaks down larger mannans into smaller oligosaccharides or individual mannose units.
Biological Role and Sources
Mannans are components of hemicellulose, a complex polysaccharide found in plant cell walls. They are abundant in plant seeds, such as coffee beans, soybeans, and softwoods. These polysaccharides serve as energy reserves for plants and contribute to their structural integrity.
In nature, mannanase is produced by microorganisms, including bacteria and fungi. Bacterial species like Bacillus lentus and Bacillus pumilus, and fungal genera such as Aspergillus and Trichoderma, are producers. These microbes secrete mannanase to digest mannans in plant biomass, using the released sugars as nutrients. This activity facilitates the breakdown of plant matter in ecosystems. Many microbial mannanases are extracellular, meaning they are secreted outside the cell, and stable across a broad range of pH and temperature conditions, enabling effectiveness in diverse environments.
Application in Animal Nutrition
The inclusion of mannanase as a feed additive has gained attention in animal agriculture, particularly for monogastric animals like poultry and swine. Common feed ingredients, notably soybean meal, palm kernel cake, and guar seeds, contain beta-mannans. These are anti-nutritional factors as animals struggle to digest them.
Undigested mannans can increase intestinal viscosity, which hinders digestion and absorption of nutrients like energy, protein, and vitamins. Mannans can also trigger an undesirable immune response in the gut, mistakenly perceiving them as pathogens. This diverts metabolic energy and nutrients towards defense rather than growth.
Adding mannanase to animal feed addresses these challenges by breaking down beta-mannans into smaller sugar molecules. This reduces intestinal viscosity, improving nutrient uptake from feed. Studies show mannanase supplementation improves feed conversion ratio (FCR) in broiler chickens by 2-3 points and increases daily weight gain, for instance, by 10.8 grams per day in nursery pigs. The enzyme also supports gut health by reducing intestinal inflammation and improving small intestine structure, such as villi height. This channels more dietary energy towards growth, potentially reducing the need for high-energy feed components like oil sources.
Uses in Food and Beverage Production
Mannanase improves product quality and processing efficiency in the food and beverage industry. In instant coffee production, mannan is a major polysaccharide component in coffee extract, contributing to its high viscosity and gelling. Mannanase hydrolyzes mannans, reducing extract viscosity and preventing gelling. This shortens filtration times and increases the extraction yield of soluble coffee solids. The enzymatic treatment also reduces energy consumption during steps like freeze-drying and forms beneficial mannooligosaccharides with prebiotic properties.
In fruit juice processing, mannanase enhances clarity and reduces thickness. Juices can appear cloudy due to the presence of polysaccharides, including mannans. Mannanase breaks down these compounds, leading to a clearer, more appealing product. This treatment improves the yield and clarity of juices from fruits like apples, oranges, peaches, grapes, pears, and kiwis. Mannanase’s ability to modify gum properties suggests minor uses in baking, where mannans like guar gum are used as thickeners and stabilizers in dough handling.
Broader Industrial and Environmental Applications
Beyond food and animal nutrition, mannanase finds diverse applications in industrial and environmental sectors. In the detergent industry, mannanase is incorporated into laundry and dishwashing formulations to enhance cleaning. Many processed foods, such as ice cream, chocolate, sauces, and salad dressings, contain mannan-based thickeners like guar gum and locust bean gum. These gums can adhere to fabrics and dishes, forming stubborn stains.
Mannanase works by breaking down these sticky mannan molecules into smaller, water-soluble sugar units, making stains much easier to remove during washing. This helps prevent soil redeposition and can reduce harsh chemical surfactants needed for effective cleaning. The enzyme’s ability to function across a wide range of pH and temperatures contributes to its versatility in detergent formulations.
Mannanase also contributes to environmentally friendly practices in the pulp and paper industry. Chemical-intensive bleaching processes used to remove lignin and improve pulp brightness generate environmental pollutants. Mannanase, often with other enzymes like xylanase, facilitates pulp bio-bleaching by breaking down hemicelluloses, including mannans. This pre-treatment helps remove lignin more efficiently, reducing the need for harsh chemicals like chlorine and hydrogen peroxide. This improves pulp brightness by 10-13% and whiteness by 2-3%, while decreasing the kappa number, an indicator of residual lignin content.
Mannanase is also explored for second-generation biofuel production. Lignocellulosic biomass, derived from plant materials like agricultural waste or wood, contains mannans that act as structural barriers. Mannanase helps break down these complex biomass components into simpler fermentable sugars, such as mannose. These sugars can then be fermented by microorganisms to produce biofuels like ethanol, offering a sustainable and efficient pathway for renewable energy.