Chitin and its N-deacetylated derivative chitosan are two biological polymers that have found numerous applications in recent years, but their further deployment suffers from limitations in obtaining a defined structure of the polymers using traditional conversion methods. The disadvantages of the currently used industrial methods of chitosan manufacturing and the increasing demand for a broad range of novel chitosan oligosaccharides (COS) with a fully defined architecture increase interest in chitin and chitosan-modifying enzymes. Enzymes such as chitinases, chitosanases, chitin deacetylases, and recently discovered lytic polysaccharide monooxygenases had attracted considerable interest in recent years. These proteins are already useful tools toward the biotechnological transformation of chitin into chitosan and chitooligosaccharides, especially when a controlled non-degradative and well-defined process is required. This review describes traditional and novel enzymatic methods of modification of chitin and its derivatives. Recent advances in chitin processing, discovery of increasing number of new, well-characterized enzymes and development of genetic engineering methods result in rapid expansion of the field. Enzymatic modification of chitin and chitosan may soon become competitive to conventional conversion methods.

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Enzymatic Modifications of Chitin, Chitosan, and Chitooligosaccharides.

Chitin is an abundant polysaccharide primarily produced as an industrial waste stream during the processing of crustaceans. Despite the limited applications of chitin, there is interest from the medical, agrochemical, food and cosmetic industries because it can be converted into chitosan and partially acetylated chitosan oligomers (COS). These molecules have various useful properties, including antimicrobial and anti-inflammatory activities. The chemical production of COS is environmentally hazardous and it is difficult to control the degree of polymerization and acetylation. These issues can be addressed by using specific enzymes, particularly chitinases, chitosanases and chitin deacetylases, which yield better-defined chitosan and COS mixtures. In this review, we summarize recent chemical and enzymatic approaches for the production of chitosan and COS. We also discuss a design-of-experiments approach for process optimization that could help to enhance enzymatic processes in terms of product yield and product characteristics. This may allow the production of novel COS structures with unique functional properties to further expand the applications of these diverse bioactive molecules.

https://www.mdpi.com/1660-3397/17/8/452/pdf

Conversion of Chitin to Defined Chitosan Oligomers: Current Status and Future Prospects.

Cloning, expression and characterization of a novel chitosanase from Streptomyces albolongus ATCC 27414

Chitooligosaccharides display anti-tumor effects against human cervical cancer cells via the apoptotic and autophagic pathways

Marine-polysaccharide degrading enzymes have recently been studied extensively. They are particularly interesting as they catalyze the cleavage of glycosidic bonds in polysaccharide macromolecules and produce oligosaccharides with low degrees of polymerization. Numerous findings have demonstrated that marine polysaccharides and their biotransformed products possess beneficial properties including antitumor, antiviral, anticoagulant, and anti-inflammatory activities, and they have great value in healthcare, cosmetics, the food industry, and agriculture. Exploitation of enzymes that can degrade marine polysaccharides is in the ascendant, and is important for high-value use of marine biomass resources. In this review, we describe research and prospects regarding the classification, biochemical properties, and catalytic mechanisms of the main types of marine-polysaccharide degrading enzymes, focusing on chitinase, chitosanase, alginate lyase, agarase, and carrageenase, and their product oligosaccharides. The state-of-the-art discussion of marine-polysaccharide degrading enzymes and their properties offers information that might enable more efficient production of marine oligosaccharides. We also highlight current problems in the field of marine-polysaccharide degrading enzymes and trends in their development. Understanding the properties, catalytic mechanisms, and modification of known enzymes will aid the identification of novel enzymes to degrade marine polysaccharides and facilitation of their use in various biotechnological processes.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/1541-4337.12630

Marine-polysaccharide degrading enzymes: Status and prospects.

Expression and characterization of a novel cold-adapted chitosanase suitable for chitooligosaccharides controllable preparation

Chitooligosaccharides are widely used in functional food, medicaments and agriculture. Controllable conversion of chitosan to chitooligosaccharides with desired degree of polymerization (DP) is of great value. Herein, a novel glycoside hydrolase family 46 chitosanase (BaCsn46A) was cloned and expressed from Bacillus amyloliquefaciens. BaCsn46A exhibited good enzymatic properties with high specific activity (1031.2 U/mg) under optimal hydrolysis conditions of pH 6.0 and 50 °C. BaCsn46A is an endo-type chitosanase, which could be utilized to yield abundant chitooligosaccharides. Furthermore, the preparation of high degree of polymerization chitooligosaccharides (DP 5–10) was investigated by BaCsn46A in an enzymatic reactor with a subsequent series of membranes. The maximum concentration of total chitooligosaccharides (DP 2–10) was 28.11 g/L (93.70% yield). The proportion of high degree of polymerization chitooligosaccharides (DP 5–10) occupied 56.17% (w/w) of total chitooligosaccharides. This study provided a cleaner production process for the controllable preparation of chitooligosaccharides with specific degree of polymerization.

Biochemical properties of a novel chitosanase from Bacillus amyloliquefaciens and its use in membrane reactor

High level production of a Bacillus amlyoliquefaciens chitosanase in Pichia pastoris suitable for chitooligosaccharides preparation

The invention relates to recombinant chitosanase as well as a production method and the application thereof, particularly to recombinant chitosanase, an encoding gene as well as a production method and the application thereof. The recombinant chitosanase provided by the invention is protein consisting of an amino acid sequence as shown in SEQ ID:1; and the encoding gene of the recombinant chitosanase is a DNA molecule as shown in SEQ ID:2. The chitosanase disclosed by the invention has excellent enzymatic properties: under the conditions that the pH is 5.5 to 6.0 and the temperature is 45 to 60 DEG C, the enzyme activity is high and the specific enzyme activity reaches to 1203 U/mg. The enzyme can effectively degrade chitosan to prepare chitosan oligosaccharide with polymerization degree of 2 to 10 and has an important industrial application value and an economic value in the enzymatic preparation of the chitosan oligosaccharide.

Sa Luo

Papers

Expression and characterization of a novel cold-adapted chitosanase suitable for chitooligosaccharides controllable preparation

Biochemical properties of a novel chitosanase from Bacillus amyloliquefaciens and its use in membrane reactor

High level production of a Bacillus amlyoliquefaciens chitosanase in Pichia pastoris suitable for chitooligosaccharides preparation

Recombinant chitosanase as well as production method and application thereof