Efficient Preparation of Chitooligosaccharide With a Potential Chitosanase Csn-SH and Its Application for Fungi Disease Protection

Chitosan and Chitooligosaccharides: Antifungal Potential and Structural Insights

Chitosan is a cationic polysaccharide derived from chitin deacetylation. This polysaccharide and its oligosaccharides have many biological activities and can be used in several fields due to their favorable characteristics, such as biodegradability, biocompatibility, and nontoxicity. This review aims to explore the antifungal potential of chitosan and chitooligosaccharides along with the conditions used for the activity and mechanisms of action they use to kill fungal cells. The sources, chemical properties, and applications of chitosan and chitooligosaccharides are discussed in this review. It also addresses the threat fungi pose to human health and crop production and how these saccharides have proven to be effective against these microorganisms. The cellular processes triggered by chitosan and chitooligosaccharides in fungal cells, and prospects for their use as potential antifungal agents are also examined.

Secretory production and characterization of a highly effective chitosanase from Streptomyces coelicolor A3(2) M145 in Pichia pastoris

In this study, a glycoside hydrolase family 46 chitosanase from Streptomyces coelicolor A3(2) M145 was firstly cloned and expressed in Pichia pastoris GS115 (P. pastoris GS115). The recombinant enzyme (CsnA) showed maximal activity at pH 6.0 and 65°C. Both thermal stability and pH stability of CsnA expressed in P. pastoris GS115 were significantly increased compared with homologous expression in Streptomyces coelicolor A3(2). A stable chitosanase activity of 725.7 ± 9.58 U mL-1 was obtained in fed-batch fermentation. It's the highest level of CsnA from Streptomyces coelicolor expressed in P. pastoris so far. The hydrolytic process of CsnA showed a time-dependent manner. Chitosan oligosaccharides (COSs) generated by CsnA showed antifungal activity against Fusarium oxysporum sp. cucumerinum (F. oxysporum sp. cucumerinum). The secreted expression and hydrolytic performance make the enzyme a desirable biocatalyst for industrial controllable production of chitooligosaccharides with specific degree of polymerization, which have potential to control fungi that cause important crop diseases.

Production, Characterization and Application of a Novel Chitosanase from Marine Bacterium Bacillus paramycoides BP-N07

Chitooligosaccharides (COS), a high-value chitosan derivative, have many applications in food, pharmaceuticals, cosmetics and agriculture owing to their unique biological activities. Chitosanase, which catalyzes the hydrolysis of chitosan, can cleave β-1,4 linkages to produce COS. In this study, a chitosanase-producing Bacillus paramycoides BP-N07 was isolated from marine mud samples. The chitosanase enzyme (BpCSN) activity was 2648.66 ± 20.45 U/mL at 52 h and was able to effectively degrade chitosan. The molecular weight of purified BpCSN was approximately 37 kDa. The yield and enzyme activity of BpCSN were 0.41 mg/mL and 8133.17 ± 47.83 U/mg, respectively. The optimum temperature and pH of BpCSN were 50 °C and 6.0, respectively. The results of the high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC) of chitosan treated with BpCSN for 3 h showed that it is an endo-chitosanase, and the main degradation products were chitobiose, chitotriose and chitotetraose. BpCSN was used for the preparation of oligosaccharides: 1.0 mg enzyme converted 10.0 g chitosan with 2% acetic acid into oligosaccharides in 3 h at 50 °C. In summary, this paper reports that BpCSN has wide adaptability to temperature and pH and high activity for hydrolyzing chitosan substrates. Thus, BpCSN is a chitosan decomposer that can be used for producing chitooligosaccharides industrially.

Production, statistical evaluation and characterization of chitosanase from Fusarium oxysporum D18

Purpose

The present research work focuses on the extraction of chitosanase enzyme from soil fungi. Chitosan hydrolysis by chitosanase is one of the most effective methods to produce chitosan oligosaccharides which are new biomaterials that have many biological activities such as antitumour, antioxidant, antidiabetic and antimicrobial.

Method

A strain producing chitosanase was screened and identified as Fusarium oxysporum D18 with an accession number OL343607. Various physiological parameters (incubation type, carbon source, additive nitrogen source, statistical evaluation, solid state fermentation) were assessed to increase chitosanase production.

Results

Fusarium oxysporum D18 produced a considerable value of chitosanase (1.220 U/ml). After 7 days of incubation, the best carbon source was lactose, and the best nitrogen source was ammonium chloride. Statistical evaluation was carried out by using Plackett–Burman and Box-Behnken designs. The highest chitosanase production (1.994 U/ml) was induced by the medium composition g/l: KH2PO4 (1.5), MgSO4 (0.269), lactose (18), NH4Cl (1.26), pH (6.68), using a 5-day-old inoculum and chitosanase activity was 1.63 folds that of the original medium. The production of chitosanase by Fusarium oxysporum D18 in solid state cultures using different solid substrates was studied and the best solid substrate for higher chitosanase activity (2.246 U/ml) was raw shrimp heads and shells and chitosanase activity was 1.13 folds that of the optimized liquid cultures. An extracellular chitosanase was isolated and partially purified by using 75% saturation of ammonium sulphate. The highest chitosanase activity (3.667 U/ml) with a specific activity of 0.390 U/mg protein was obtained at enzyme protein concentration of 9.391 mg/ml, substrate concentration of 1.2 % (w/v), Vmax of the enzyme of approximately 0.430 U/mg protein, and KM of 0.26 % (w/v), at pH 5.6 and reaction temperature of 50 °C. The activity of the purified and characterized chitosanase increased by 3 times than that the original isolate activity. The enzyme was thermostable and retained about 55% of its original activity after heating at 70 °C for 15 min. The enzyme preparations were activated by Ca2+ ions and inactivated by Zn+2, Cu+2 ions, and EDTA.

Conclusion

An antitumour activity of chitooligosaccharides produced by the chitosanase was applied to the MCF-7 (breast carcinoma cells) and they had a cytotoxicity inhibitory effect against them about IC50 = 448 μg/ml.

Homogeneous preparation of water-soluble products from chitin under alkaline conditions and their cell proliferation in vitro

The purpose of this study was to prepare water-soluble products by homogeneous depolymerization of chitin with H₂O₂ under alkaline conditions and investigate their potential application in wound healing. For the first time, water-soluble products were successfully prepared using a chitin-NaOH/urea solution; the products were chitosans with molecular weights (Mw) of 3.48-33.5 kDa and degrees of deacetylation (DD) > 0.5. Their Mw, DD and yield were affected by the reaction temperature, reaction time, concentration of H₂O₂ and chitin DD. The deacetylation and depolymerization of chitin were achieved simultaneously. The depolymerization of chitin was caused by hydrogen abstraction of HO, whereas the deacetylation resulted from the cleavage of amide bonds by HO^- and HO₂^-, although the latter played a more important role. All water-soluble chitosans markedly promoted the proliferation of human skin fibroblast (HSF) cells, but they inhibited the proliferation of human keratinocyte cells. For the proliferation of HSF, a low concentration of chitosans was important. In addition, water-soluble chitosans with an Mw of 3.48-16.4 kDa markedly stimulated the expression of growth factors such as PDGF and TGF-β by macrophages. Water-soluble chitosans could be used as a potential active component in wound dressings.

Preparation of chitooligosaccharides with a low degree of polymerization and anti-microbial properties using the novel chitosanase AqCsn1

Chitosanases hydrolyze chitosan into chitooligosaccharides (COSs) with various biological activities, which are widely employed in many areas including plant disease management. In this study, the novel chitosanase AqCsn1 belonging to the glycoside hydrolase family 46 (GH46) was cloned from Aquabacterium sp. A7-Y and heterologously expressed in Escherichia coli BL21 (DE3). AqCsn1 displayed the highest hydrolytic activity towards chitosan with 95% degree of deacetylation at 40 °C and pH 5.0, with a specific activity of 13.18 U/mg. Product analysis showed that AqCsn1 hydrolyzed chitosan into (GlcN)₂ and (GlcN)₃ as the main products, demonstrating an endo-type cleavage pattern. Evaluation of antagonistic activity showed that the hydrolysis products of AqCsn1 suppress the mycelial growth of Magnaporthe oryzae and Phytophthora sojae in a concentration-dependent manner, and the inhibition rate of P. sojae reached 39.82% at a concentration of 8 g/L. Our study demonstrates that AqCsn1 and hydrolysis products with a low degree of polymerization might have potential applications in the biological control of agricultural diseases.

Chitinase-Assisted Bioconversion of Chitinous Waste for Development of Value-Added Chito-Oligosaccharides Products

Chito-oligosaccharides (COSs) are the partially hydrolyzed products of chitin, which is abundant in the shells of crustaceans, the cuticles of insects, and the cell walls of fungi. These oligosaccharides have received immense interest in the last few decades due to their highly promising bioactivities, such as their anti-microbial, anti-tumor, and anti-inflammatory properties. Regarding environmental concerns, COSs are obtained by enzymatic hydrolysis by chitinase under milder conditions compared to the typical chemical degradation. This review provides updated information about research on new chitinase derived from various sources, including bacteria, fungi, plants, and animals, employed for the efficient production of COSs. The route to industrialization of these chitinases and COS products is also described.

Controllable preparation of chitosan oligosaccharides via a recombinant chitosanase from marine Streptomyces lydicus S1 and its potential application on preservation of pre-packaged tofu

Chitosan oligosaccharides (COSs) are widely applied in many areas due to its various biological activities. Controllable preparation of COSs with desired degree of polymerization (DP) via suitable chitosanase is of great value. Herein, a novel glycoside hydrolase (GH) family 46 chitosanase (SlCsn46) from marine Streptomyces lydicus S1 was prepared, characterized and used to controllably produce COSs with different DP. The specific activity of purified recombinant SlCsn46 was 1,008.5 U/mg. The optimal temperature and pH of purified SlCsn46 were 50°C and 6.0, respectively. Metal ions Mn2+ could improve the stability of SlCsn46. Additionally, SlCsn46 can efficiently hydrolyze 2% and 4% colloidal chitosan to prepare COSs with DP 2–4, 2–5, and 2–6 by adjusting the amount of SlCsn46 added. Moreover, COSs with DP 2–4, 2–5, and 2–6 exhibited potential application value for prolonging the shelf-life of pre-packaged Tofu. The water-holding capacity (WHC), sensorial properties, total viable count (TVC), pH and total volatile base nitrogen (TVB-N) of pre-packed tofu incorporated with 4 mg/mL COSs with DP 2–4, 2–5, and 2–6 were better than those of the control during 15 days of storage at 10°C. Thus, the controllable hydrolysis strategy provides an effective method to prepare COSs with desired DP and its potential application on preservation of pre-packed tofu.

Overexpression and Biochemical Properties of a GH46 Chitosanase From Marine Streptomyces hygroscopicus R1 Suitable for Chitosan Oligosaccharides Preparation

Due to the various biological activities of chitosan oligosaccharides (COSs), they have great potential value for use in many areas. Chitosanase plays an important role in enzymatic preparation of COSs. Herein, a gene encoding a chitosanase (ShCsn46) from marine Streptomyces hygroscopicus R1 was cloned and the sequences encoding ShCsn46 without signal peptide were optimized based on the codon usage of Pichia pastoris (P. pastoris). In addition, the optimized gene was ligated to pPICZαA and transformed to P. pastoris X33. After screening, a recombinant strain named X33-Sh33 with the highest activity was isolated from 96 recombinant colonies. The maximum activity and total protein concentration of the recombinant strain ShCsn46 were 2250 U/ml and 3.98 g/l, respectively. The optimal pH and temperature of purified ShCsn46 were 5.5 and 55°C, respectively. Meanwhile, ShCsn46 was stable from pH 5.0 to 10.0 and 40 to 55°C, respectively. The purified ShCsn46 was activated by Mn²⁺ and inhibited by Cu²⁺, Fe²⁺, and Al³⁺. In addition, substrate specificity of the purified ShCsn46 showed highest activity toward colloidal chitosan with 95% degree of deacetylation. Furthermore, the purified ShCsn46 exhibited high efficiency to hydrolyze 4% colloidal chitosan to prepare COSs. COSs with degree of polymerization of 2–6, 2–5, and 2–4 were controllably produced by adjusting the reaction time. This study provides an excellent chitosanase for the controllable preparation of COSs with a desirable degree of polymerization.

Heterologous Expression and Characterization of a High-Efficiency Chitosanase From Bacillus mojavensis SY1 Suitable for Production of Chitosan Oligosaccharides

Chitosanase plays an important role in enzymatic production of chitosan oligosaccharides (COSs). The present study describes the gene cloning and high-level expression of a high-efficiency chitosanase from Bacillus mojavensis SY1 (CsnBm). The gene encoding CsnBm was obtained by homologous cloning, ligated to pPICZαA, and transformed into Pichia pastoris X33. A recombinant strain designated X33-C3 with the highest activity was isolated from 120 recombinant colonies. The maximum activity and total protein concentration of recombinant strain X33-C3 were 6,052 U/ml and 3.75 g/l, respectively, which were obtained in fed-batch cultivation in a 50-l bioreactor. The optimal temperature and pH of purified CsnBm were 55°C and 5.5, respectively. Meanwhile, CsnBm was stable from pH 4.0 to 9.0 and 40 to 55°C. The purified CsnBm exhibited high activity toward colloidal chitosan with degrees of deacetylation from 85 to 95%. Furthermore, CsnBm exhibited high efficiency to hydrolyze different concentration of colloidal chitosan to produce COSs. The result of this study not only identifies a high-efficiency chitosanase for preparation of COSs, but also casts some insight into the high-level production of chitosanase in heterologous systems.