Xylanases are widely distributed in nature and can be obtained from animals, plants and microorganisms. Xylanase is present in marine and terrestrial bacteria, marine algae, fungi, yeast, rumen and ruminant bacteria, snails, crustaceans, land plant tissues and various of invertebrates.
Source of xylanase
Xylanases are widely distributed in nature and can be obtained from animals, plants and microorganisms. Xylanase is present in marine and terrestrial bacteria, marine algae, fungi, yeast, rumen and ruminant bacteria, snails, crustaceans, land plant tissues and various invertebrates. Microbial xylanases are widely found in nature and have a wide range of applications. Therefore, many studies on microbial xylanases have been reported. The most recently researched and applied are xylanase derived from bacteria and fungi. Among them, bacteria can produce alkaline and acid xylanase, while fungi can only produce alkaline xylanase. Among the fungi, filamentous fungi secreted the highest extracellular enzymes. At present, xylanase mainly uses microorganisms such as fungi and bacteria for fermentation production.
How xylanase works
Xylanases are a class of enzymes that degrade xylan, including β-1,4-endo-xylanase, β-xylosidase, α-L-arabinosidase, α-D-glucose Glucuronidase, acetyl xylanase and phenolate esterase. It can degrade xylan hemicellulose which is abundant in nature. In the xylan hydrolase system, β-1,4-endo-xylanase is the most critical hydrolase. It hydrolyzes xylan by hydrolyzing the β-1,4-glycosidic bonds of xylan molecules, xylooligosaccharides such as small oligosaccharides and xylulose, as well as a small amount of xylose and arabinose. Beta-xylosidase catalyzes the release of xylose residues by hydrolyzing the end of xylooligosaccharides. In addition, α-L-arabinofuranosidase, α-glucuronidase, acetylxylan esterase, and the degradation of arabinose side chain residues and phenol in xylan are also involved in the complete degradation of xylan. Side chain hydrolases such as phenolic esterase formed by acids (such as ferulic acid or coumaric acid), which act on glycosidic bonds between xylose and side chain substituents, and cooperate with the main chain hydrolase. Ultimately, xylan is converted into its constituent monosaccharide.
Application of xylanase
Xylan is the main component of hemicellulose in plant cells, accounting for 35% of the dry weight of plant cells. It is a rich biomass resource and the most abundant polysaccharide in nature except cellulose.
During the pulp cooking process, xylan was partially dissolved, denatured and re-deposited on the fiber surface, causing the pulp matrix to become clogged. Xylanase is a specific enzyme that degrades xylan. It only degrades xylan and cannot degrade cellulose. If xylanase is used in this process, part of the re-deposited xylan can be removed. This not only increases the porosity of the pulp matrix, releases the trapped soluble lignin, but also allows the chemical bleach to penetrate into the pulp more effectively. In this way, the bleaching rate of pulp can be increased and the amount of chemical bleaching agent can be reduced, thereby reducing the pollution to nature during the papermaking process.
Xylanase can decompose raw material cell wall and β-glucan in brewing or feed industry, reduce the viscosity of materials in brewing, and promote the release of effective substances. Non-starch polysaccharides in feed grains will be reduced, thereby promoting the absorption and utilization of nutrients, and thus making it easier to take soluble lipid components.
β-1,4-xylanase can endogenously act on the main chain of xylan to produce xylooligosaccharides of different lengths and a small amount of xylose. It is the main enzyme in xylan degrading enzyme system. At present, no research report on the application of xylanase in noodle processing has been found, but because xylanase can hydrolyze pentosan, increase the water solubility of non-starch polysaccharides, and reduce their binding power with water, it can release a large amount of bound water. This water can provide starch and gluten, so that the dough forms a better gluten network structure, improves the dough's mechanical processing performance, and improves the quality of noodles.
The Naming and Characteristics of Restriction Endonucleases
Restriction enzymes, also known as restriction endonucleases, are enzymes that cut double-stranded DNA. Its cutting method is to cut the bond between the carbohydrate molecule and the phosphoric acid, and then create a nick on each of the two DNA strands without damaging the nucleotides and bases.
Introduction to Classification and Application of Cellulase
The optimum pH of cellulase is generally 4.5 to 6.5, which acts on cellulose and products derived from cellulose. Microbial cellulase is of great significance in converting insoluble cellulose into glucose and destroying cell walls in fruit and vegetable juice to improve the yield of juice.
Which Enzyme Preparations Are Often Used in Fruit and Vegetable Processing?
The so-called fruit and vegetable processing means to maximize the nutrient content of the fruit and vegetable through various processing methods, improve the edible value, and make the color, aroma and taste of the processed product more perfect.
