Chitosanase

Chitosan

Chitosan is the product of the deacetylation of chitin. It is the only alkaline polysaccharide present in nature. It is biodegradable, non-toxic to animals, soluble in acidic solutions, available in many physical forms, and easier to handle Features. Chitosanase was first introduced in 1973. It is a specific enzyme that has a decomposition effect on linear chitosan. It can selectively and specifically cut β- (1-4) -glycosidic bonds Chito-oligosaccharides with a specific molecular weight range are obtained.

Figure 1. Structure of chitosan.

Occurrence and distribution of chitosanases

Chitosanase is produced by microbes and plants, where they play an important role in nutrition and defence. Chitosanase was first described in 1973 from different soil microorganisms. Over the past 40 years, several research papers have been published on the occurrence, production, purification and characterization of chitosanase from different microorganisms including bacteria, fungi and cyanobacteria; and plants.

Figure 2. Protein structure of chitosanase.

Plant chitosanases

Chitosanases are mostly found in microorganisms (bacteria and fungi), however, very few of them have been reported in plants. Chitosanase activity has been detected in vesicular–arbuscular mycorrhizal colonised leek and onion root as well as chemical or pathogen stressed leaves of various plant species. In addition, chitosanase activity has been detected in different parts of healthy plants. Chitosan and COS can induce defence reactions in plants including the induction of chitosanase and 1,3-glucanase isoforms. The endogenous function of plant chitosanases, however, has not yet been elucidated.

Chitosanase fermentation production

Chitosanase is considered to be a disease-resistant protein in plants. Therefore, some people tried to clone the gene encoding chitosanase into fine crops through genetic engineering technology, so as to improve crop quality. The substrate specificity of chitosanase can be used to study the cell wall composition and special physiological processes of some special fungi and algae. Chitosanase is a specific enzyme that decomposes chitosan. It is widely distributed in bacteria, fungi, viruses and plants and biota. Since most microorganisms have low chitosanase activity, the production cost is relatively high Has always affected the enzymatic production of chitosan. Most microbial chitosanases are inducible enzymes. Adding colloidal chitosan to the culture medium to induce the expression of chitosanase is a common strategy. It has an inducing effect on the production of many chitosanases. In addition, chitosan powder, chitin, squid pen powder and shrimp shell powder can also induce the production of chitosanase. In order to mass-produce chitosanase to meet the needs of commercialization, in the fermentation process of chitosanase, it is usually necessary to optimize various parameters. A suitable and cheap medium is the basis for optimizing the production process. Therefore, the first optimization of fermentation is the research and development of the medium, including the selection of various nutrients and the optimization of the corresponding concentration.

Application

The application of chitosanase is closely related to its own properties. The application of chitosanase is also diverse, mainly studied in the following aspects:

a. Preparation of fungal protoplasts

Chitosan specifically degrades chitosan. Some researchers use chitosanase to produce fungal protoplasts, which are directly used in genetic hybridization experiments of strains, especially for those cell walls Zygomycetes, whose ingredient is chitosan, are more effective.

b. Inhibition of plant pathogenic bacteria

The main component of most fungal cell walls is chitosan. Studies have found that chitosanase can be used to degrade the cell wall of plant pathogenic fungi, analyze the cell wall composition of pathogenic fungi, and speculate on the pathogenesis of some fungi on plant diseases. Further effectively prevent and control pathogenic bacteria, and increase the output of crops, especially some economic crops.

c. Preparation of chitooligosaccharides

Another major application of chitosanase is to degrade chitosan to produce chitosan oligosaccharides with great economic benefit and specific degree of polymerization. Chitosan oligosaccharides not only have the advantages of good water solubility and easy absorption, etc. It also has the functions of anti-bacteria, fungus, regulating body immunity and anti-cancer, etc. It has a wide range of applications in functional foods, health care medicines and other industries. Since the stability of chitosan limits the large-scale application of chitosanase, the application research of chitosanase is mainly carried out around two aspects, one is to improve the catalytic activity of chitosanase itself, and the other is Improve the stability of chitosanase. Improving the catalytic activity of chitosanase mainly includes the improvement of strains and the construction of chitosan recombinase. The study on the stability of chitosanase mainly uses immobilization technology to immobilize chitosanase.

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