Enzymolysis of chitosan by papain and its kinetics

The development of multifunctional materials for water pollution remediation using pollen and sporopollenin

Pollen is a promising material for water treatment owing to its renewable nature, abundant sources, and vast reserves. The natural polymer sporopollenin, found within pollen exine, possesses a distinctive layered porous structure, mechanical strength, and stable chemical properties, which can be utilized to prepare sporopollenin exine capsules (SECs). Leveraging these attributes, pollen or SECs can be used to develop water pollution remediation materials. In this review, the structure of pollen is first introduced, followed by the categorization of various methods for extracting SECs. Then, the functional expansion of pollen adsorbents, with an emphasis on their recyclability, reusability, and visual sensing capabilities, as opposed to mere functional group modification, is discussed. Furthermore, the progress made in utilizing pollen as a biological template for synthesizing catalysts is summarized. Intriguingly, pollen can also be engineered into self-propelled micromotors, enhancing its potential application in adsorption and catalysis. Finally, the challenges associated with the application of pollen in water pollution treatment are discussed. These challenges include the selection of environmentally friendly, non-toxic reagents in synthesizing pollen water remediation products and the large-scale application after synthesis. Moreover, the multifunctional synthesis and application of different water remediation products are prospected.

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.

Crude Enzyme Concentrate of Filamentous Fungus Hydrolyzed Chitosan to Obtain Oligomers of Different Sizes

Chitosan is a non-cytotoxic polysaccharide that, upon hydrolysis, releases oligomers of different sizes that may have antioxidant, antimicrobial activity and the inhibition of cancer cell growth, among other applications. It is, therefore, a hydrolysis process with great biotechnological relevance. Thus, this study aims to use a crude enzyme concentrate (C_EC) produced by a filamentous fungus to obtain oligomers with different molecular weights. The microorganism was cultivated in a liquid medium (modified Czapeck-with carboxymethylcellulose as enzyme inducer). The enzymes present in the C_EC were identified by LC-MS/MS, with an emphasis on cellobiohydrolase (E.C 3.2.1.91). The fungus of the Aspergillus genus was identified by amplifying the ITS1-5.8S-ITS2 rDNA region and metaproteomic analysis, where the excreted enzymes were identified with sequence coverage greater than 84% to A. nidulans. Chitosan hydrolysis assays compared the C_EC with the commercial enzyme (Celluclast 1.5 L^®). The ability to reduce the initial molecular mass of chitosan by 47.80, 75.24, and 93.26% after 2.0, 5.0, and 24 h of reaction, respectively, was observed. FTIR analyses revealed lower absorbance of chitosan oligomers' spectral signals, and their crystallinity was reduced after 3 h of hydrolysis. Based on these results, we can conclude that the crude enzyme concentrate showed a significant technological potential for obtaining chitosan oligomers of different sizes.

Chitosan targets PI3K/Akt/FoxO3a axis to up-regulate FAM172A and suppress MAPK/ERK pathway to exert anti-tumor effect in osteosarcoma

Osteosarcoma (OS) is a serve and the most frequent primary malignant tumor of bone. Chitosan was reported to have anti-tumor effect on human cancers including OS. However, the molecular mechanism by which chitosan suppresses tumor growth is not fully illustrated. In this study, human OS cell lines, including both Saos-2 and U2OS cells, were used to dissect the underlying mechanisms. RNA sequencing results show that a candidate biomarker family with sequence similarity 172 member A (FAM172A) was up-regulated in both of the two cell lines treated with chitosan. We observed that the mitogen-activated protein kinase (MAPK) signaling pathway could be inactivated by chitosan, and the MAPK inhibition caused by chitosan was reversed by FAM172A knockdown. Moreover, we uncovered a direct interaction between C-terminal domain of FAM172A (311-415) and mitogen-activated protein kinase kinase 1 (MEK1) (270-307) by immunoprecipitation assay. Finally, we also found that chitosan could bind with subunit p85 of PI3K to further inactivate the PI3K/Akt pathway. Taken together, our study demonstrates that chitosan binds with PI3K p85 subunit to suppress the activity of PI3K/Akt pathway to up-regulate the expression of FAM172A, and which exerts its function by suppressing phosphorylation of MEK1/2 and blocking the activity of MAPK/ERK signaling pathway. Taken together, our study deepens the understanding of the molecular mechanism of MAPK/ERK pathway inhibition induced by chitosan, and provides insights into the development of new targets to enhance the pharmacological effect of chitosan against OS.

Preparation and antibacterial effect of chitooligosaccharides monomers with different polymerization degrees from crab shell chitosan by enzymatic hydrolysis

This study aimed to explore the structure and antibacterial properties of chitooligosaccharide monomers with different polymerization degrees and to provide a theoretical basis for inhibiting Salmonella infection. Chitosan was used as a raw material to prepare and separate low-molecular-weight chitooligosaccharides. Chitobiose, chitotriose, and chitotetraose were obtained by gradient elution with cation exchange resin. The molecular weights and acetyl groups of the three monomers were determined by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) and nuclear magnetic resonance (NMR), respectively. Three chitooligosaccharide monomers were used to explore the antibacterial effect on Salmonella. The results showed that the degree of deacetylation of chitosan was 92.6%, and the enzyme activity of chitosanase was 102.53 U/g. Within 18 h, chitosan was enzymatically hydrolyzed to chitooligosaccharides containing chitobiose, chitotriose, and chitotetraose, which were analyzed by thin-layer chromatography (TLC) and MALDI-TOF. MALD-TOF and TLC showed that the separation of monomers with ion exchange resins was effective, and NMR showed that there was no acetyl group. Chitobiose had a poor inhibitory effect on Salmonella, and chitotriose and chitotetraose had equivalent antibacterial effects.

Chitosan-Based Materials: An Overview of Potential Applications in Food Packaging

Chitosan is a multifunctional biopolymer that is widely used in the food and medical fields because of its good antibacterial, antioxidant, and enzyme inhibiting activity and its degradability. The biological activity of chitosan as a new food preservation material has gradually become a hot research topic. This paper reviews recent research on the bioactive mechanism of chitosan and introduces strategies for modifying and applying chitosan for food preservation and different preservation techniques to explore the potential application value of active chitosan-based food packaging. Finally, issues and perspectives on the role of chitosan in enhancing the freshness of food products are presented to provide a theoretical basis and scientific reference for subsequent research.

Mechanism and Application of Chitosan and Its Derivatives in Promoting Permeation in Transdermal Drug Delivery Systems: A Review

The mechanisms and applications of chitosan and its derivatives in transdermal drug delivery to promote drug permeation were reviewed in this paper. Specifically, we summarized the permeation-promoting mechanisms of chitosan and several of its derivatives, including changing the structure of stratum corneum proteins, acting on the tight junction of granular layers, affecting intercellular lipids, and increasing the water content of stratum corneum. These mechanisms are the reason why chitosan and its derivatives can increase the transdermal permeation of drugs. In addition, various transdermal preparations containing chitosan and its derivatives were summarized, and their respective advantages were expounded, including nanoparticles, emulsions, transdermal microneedles, nanocapsules, transdermal patches, transdermal membranes, hydrogels, liposomes, and nano-stents. The purpose of this review is to provide a theoretical basis for the further and wider application of chitosan in transdermal drug delivery systems. In the future, research results of chitosan and its derivatives in transdermal drug delivery need more support from in vivo experiments, as well as good correlation between in vitro and in vivo experiments. In conclusion, the excellent permeability-promoting property, good biocompatibility, and biodegradability of chitosan and its derivatives make them ideal materials for local transdermal drug delivery.

Production of Low Molecular Weight Chitosan and Chitooligosaccharides (COS): A Review

Chitosan is a biopolymer with high added value, and its properties are related to its molecular weight. Thus, high molecular weight values provide low solubility of chitosan, presenting limitations in its use. Based on this, several studies have developed different hydrolysis methods to reduce the molecular weight of chitosan. Acid hydrolysis is still the most used method to obtain low molecular weight chitosan and chitooligosaccharides. However, the use of acids can generate environmental impacts. When different methods are combined, gamma radiation and microwave power intensity are the variables that most influence acid hydrolysis. Otherwise, in oxidative hydrolysis with hydrogen peroxide, a long time is the limiting factor. Thus, it was observed that the most efficient method is the association between the different hydrolysis methods mentioned. However, this alternative can increase the cost of the process. Enzymatic hydrolysis is the most studied method due to its environmental advantages and high specificity. However, hydrolysis time and process cost are factors that still limit industrial application. In addition, the enzymatic method has a limited association with other hydrolysis methods due to the sensitivity of the enzymes. Therefore, this article seeks to extensively review the variables that influence the main methods of hydrolysis: acid concentration, radiation intensity, potency, time, temperature, pH, and enzyme/substrate ratio, observing their influence on molecular weight, yield, and characteristic of the product.

Radiopaque Chitosan Ducts Fabricated by Extrusion-Based 3D Printing to Promote Healing After Pancreaticoenterostomy

Long-term placement of non-degradable silicone rubber pancreatic duct stents in the body is likely to cause inflammation and injury. Therefore, it is necessary to develop degradable and biocompatible stents to replace silicone rubber tubes as pancreatic duct stents. The purpose of our research was to verify the feasibility and biological safety of extrusion-based 3D printed radiopaque chitosan (CS) ducts for pancreaticojejunostomy. Chitosan-barium sulfate (CS-Ba) ducts with different molecular weights (low-, medium-, and high-molecular weight CS-Ba: LCS-Ba, MCS-Ba, and HCS-Ba, respectively) were soaked in vitro in simulated pancreatic juice (SPJ) (pH 8.0) with or without pancreatin for 16 weeks. Changes in their weight, water absorption rate and mechanical properties were tested regularly. The biocompatibility, degradation and radiopaque performance were verified by in vivo and in vitro experiments. The results showed that CS-Ba ducts prepared by this method had regular compact structures and good molding effects. In addition, the lower the molecular weight of the CS-Ba ducts was, the faster the degradation rate was. Extrusion-based 3D-printed CS-Ba ducts have mechanical properties that match those of soft tissue, good biocompatibility and radioopacity. In vitro studies have also shown that CS-Ba ducts can promote the growth of fibroblasts. These stents have great potential for use in pancreatic duct stent applications in the future.

Advances in the preparation and assessment of the biological activities of chitosan oligosaccharides with different structural characteristics

Chitosan oligosaccharides (COSs) are widely used biopolymers that have been studied in relation to a variety of abnormal biological activities in the food and biomedical fields. Since different COS preparation technologies produce COS compounds with different structural characteristics, it has not yet been possible to determine whether one or more chito-oligomers are primarily responsible for the bioactivity of COSs. The inherent biocompatibility, mucosal adhesion and nontoxic nature of COSs are well documented, as is the fact that they are readily absorbed from the intestinal tract, but their structure-activity relationship requires further investigation. This review summarizes the methods used for COS preparation, and the research findings with regard to the antioxidant, anti-inflammatory, anti-obesity, bacteriostatic and antitumour activity of COSs with different structural characteristics. The correlation between the molecular structure and bioactivities of COSs is described, and new insights into their structure-activity relationship are provided.

Optimizing Chitin Depolymerization by Lysozyme to Long-Chain Oligosaccharides

Chitin oligosaccharides (COs) hold high promise as organic fertilizers in the ongoing agro-ecological transition. Short- and long-chain COs can contribute to the establishment of symbiotic associations between plants and microorganisms, facilitating the uptake of soil nutrients by host plants. Long-chain COs trigger plant innate immunity. A fine investigation of these different signaling pathways requires improving the access to high-purity COs. Here, we used the response surface methodology to optimize the production of COs by enzymatic hydrolysis of water-soluble chitin (WSC) with hen egg-white lysozyme. The influence of WSC concentration, its acetylation degree, and the reaction time course were modelled using a Box–Behnken design. Under optimized conditions, water-soluble COs up to the nonasaccharide were formed in 51% yield and purified to homogeneity. This straightforward approach opens new avenues to determine the complex roles of COs in plants.

Enzymatic Synthesis and Characterization of Different Families of Chitooligosaccharides and Their Bioactive Properties

Chitooligosaccharides (COS) are homo- or hetero-oligomers of D-glucosamine (GlcN) and N-acetyl-D-glucosamine (GlcNAc) that can be obtained by chitosan or chitin hydrolysis. Their enzymatic production is preferred over other methodologies (physical, chemical, etc.) due to the mild conditions required, the fewer amounts of waste and its efficiency to control product composition. By properly selecting the enzyme (chitinase, chitosanase or nonspecific enzymes) and the substrate properties (degree of deacetylation, molecular weight, etc.), it is possible to direct the synthesis towards any of the three COS types: fully acetylated (faCOS), partially acetylated (paCOS) and fully deacetylated (fdCOS). In this article, we review the main strategies to steer the COS production towards a specific group. The chemical characterization of COS by advanced techniques, e.g., high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and MALDI-TOF mass spectrometry, is critical for structure–function studies. The scaling of processes to synthesize specific COS mixtures is difficult due to the low solubility of chitin/chitosan, the heterogeneity of the reaction mixtures, and high amounts of salts. Enzyme immobilization can help to minimize such hurdles. The main bioactive properties of COS are herein reviewed. Finally, the anti-inflammatory activity of three COS mixtures was assayed in murine macrophages after stimulation with lipopolysaccharides.

Production of chitosan-oligosaccharides by the chitin-hydrolytic system of Trichoderma harzianum and their antimicrobial and anticancer effects

Chitosan-oligosaccharides (COS) are low-molecular weight chitosan derivatives with interesting clinical applications. The optimization of both COS production and purification is an important step in the design of an efficient production system and for the exploration of new COS applications. Trichoderma harzianum is an innocuous biocontrol agent that represents a novel biotechnological tool due to the production of extracellular enzymes, including those that produce a COS mixture. In this work, we propose different systems for the production of COS using the T. harzianum chitinolitic system. A complete qualitative and quantitative analysis of a partially purified COS mixture were performed. Also, an evaluation of the anticancer and antimicrobial effects of the COS mixture was carried out. Three chitosan variants (colloidal, solid and solution) and two fungus stages (spores and mycelia) were tested for COS production. The best system consisted of the interaction of the solid chitosan and the fungal spores, producing a COS mixture containing species from the monomer to the hexamer, in a concentration range of 7-238 mg/mL, according to chromatographic analysis. The proposed purification method isolated the monomer and the dimer from the COS mixture. Moreover, the COS mixture has an inhibitory effect on the growth of bacteria and changes the morphology of yeasts. As anticancer compounds, COS inhibited the growth of cervical cancer cells at concentration of 4 mg/mL and significantly reduced the survival rate of the cells. In conclusion, T. harzianum proved to be an efficient system for COS mixture production.

Modification of Chitosan for the Generation of Functional Derivatives

Today, chitosan (CS) is probably considered as a biofunctional polysaccharide with the most notable growth and potential for applications in various fields. The progress in chitin chemistry and the need to replace additives and non-natural polymers with functional natural-based polymers have opened many new opportunities for CS and its derivatives. Thanks to the specific reactive groups of CS and easy chemical modifications, a wide range of physico-chemical and biological properties can be obtained from this ubiquitous polysaccharide that is composed of β-(1,4)-2-acetamido-2-deoxy-d-glucose repeating units. This review is presented to share insights into multiple native/modified CSs and chitooligosaccharides (COS) associated with their functional properties. An overview will be given on bioadhesive applications, antimicrobial activities, adsorption, and chelation in the wine industry, as well as developments in medical fields or biodegradability.

Fate of pharmaceutically active compounds in sewage sludge during anaerobic digestions integrated with enzymes and physicochemical treatments

The removal of 4 typical pharmaceutically active compounds (PhACs) in sewage sludge, i.e. diclofenac (DCF), clofibric acid (CFA), carbamazepine (CBM), and triclosan (TCS), was evaluated during 3 integrated processes of anaerobic digestions (ADs). The integrated processes included ADs integrated with mixed enzymolyses (MEADs), ADs integrated with mixed enzymolyses together with ultrasonic irradiation pre-treatment (MEUADs), and ADs integrated with mixed enzymolyses together with mechanical rotary disc post-treatment (MEADRDs). The SRTs were set at 15 d. Gas chromatography-mass spectrometry (GC/MS) following solid-phase extraction was used to analyze and detect the target compounds. Under the mesophilic condition, the highest removal during MEAD and MEUAD was 67.6% and 77.1% of CFA, and 78.1% of CBZ during MEADRD. There was little differences between the removals of 4 PhACs during MEADRD, and all the removal rates were higher than 70%. Especially the removal of DCF increased from 40.6% during MEAD to 71.7% during MEADRD. The overall removal during MEADRD was highest with the increase by about 20.9% from that during MEAD. The highest removal during MEAD, MEUAD and MEADRD was 81.1%, 70.7% and 71.8%, respectively, of CFA under the thermophilic condition. MEADRD could realize the highest overall removal, up to 69.4% with the increase by 11.0% compared with MEUAD. The results showed that the integrated process, MEADRD, under both mesophilic and thermophilic condition was suitable for the effective removal of PhACs, and MEADRD under the mesophilic condition was a preferable choice from the energy-saving perspective.

Protein-tannic acid multilayer films: A multifunctional material for microencapsulation of food-derived bioactives

The benefits of various functional foods are often negated by stomach digestion and poor targeting to the lower gastrointestinal tract. Layer-by-Layer assembled protein-tannic acid (TA) films are suggested as a prospective material for microencapsulation of food-derived bioactive compounds. Bovine serum albumin (BSA)-TA and pepsin-TA films demonstrate linear growth of 2.8±0.1 and 4.2±0.1nm per bi-layer, correspondingly, as shown by ellipsometry. Both multilayer films are stable in simulated gastric fluid but degrade in simulated intestinal fluid. Their corresponding degradation constants are 0.026±0.006 and 0.347±0.005nm^-1min^-1. Milk proteins possessing enhanced adhesion to human intestinal surface, Immunoglobulin G (IgG) and β-Lactoglobulin (BLG), are explored to tailor targeting function to BSA-TA multilayer film. BLG does not adsorb onto the multilayer while IgG is successfully incorporated. Microcapsules prepared from the multilayer demonstrate 2.7 and 6.3 times higher adhesion to Caco-2 cells when IgG is introduced as an intermediate and the terminal layer, correspondingly. This developed material has a great potential for oral delivery of numerous active food-derived ingredients.

pH Dependence of Chitosan Enzymolysis

As a means of making chitosan more useful in biotechnological applications, it was hydrolyzed using pepsin, chitosanase and α-amylase. The enzymolysis behavior of these enzymes was further systematically studied for its effectiveness in the production of low-molecular-weight chitosans (LMWCs) and other derivatives. The study showed that these enzymes depend on ion hydronium (H3O+), thus on pH with a pH dependence fitting R2 value of 0.99. In y = 1.484[H^+] + 0.114, the equation of pH dependence, when [H^+] increases by one, y (k_0/k_m) increases by 1.484. From the temperature dependence study, the activation energy (Ea) and pre-exponential factor (A) were almost identical for two of the enzymes, but a considerable difference was observed in comparison with the third enzyme. Chitosanase and pepsin had nearly identical Ea, but α-amylase was significantly lower. This serves as evidence that the hydrolysis reaction of α-amylase relies on low-barrier hydrogen bonds (LBHBs), which explains its low Ea in actual conditions. The confirmation of this phenomenon was further derived from a similarly considerable difference in the order magnitudes of A between α-amylase and the other two enzymes, which was more than five. Variation of the rate constants of the enzymatic hydrolysis of chitosan with temperature follows the Arrhenius equation.

Optimization and Characterization of Chitosan Enzymolysis by Pepsin

Pepsin was used to effectively degrade chitosan in order to make it more useful in biotechnological applications. The optimal conditions of enzymolysis were investigated on the basis of the response surface methodology (RSM). The structure of the degraded product was characterized by degree of depolymerization (DD), viscosity, molecular weight, FTIR, UV-VIS, SEM and polydispersity index analyses. The mechanism of chitosan degradation was correlated with cleavage of the glycosidic bond, whereby the chain of chitosan macromolecules was broken into smaller units, resulting in decreasing viscosity. The enzymolysis by pepsin was therefore a potentially applicable technique for the production of low molecular chitosan. Additionally, the substrate degradation kinetics of chitosan were also studied over a range of initial chitosan concentrations (3.0~18.0 g/L) in order to study the characteristics of chitosan degradation. The dependence of the rate of chitosan degradation on the concentration of the chitosan can be described by Haldane’s model. In this model, the initial chitosan concentration above which the pepsin undergoes inhibition is inferred theoretically to be about 10.5 g/L.

Heat-pretreatment and enzymolysis behavior of the lotus seed protein

Lotus seed protein (LSP) was heat-pretreated before enzymolysis in order to seek a greater degree of hydrolysis (DH) during enzymatic hydrolysis. The parameters including substrate concentration, temperature, pH, and papain concentration were optimized by response surface methodology in the enzymolysis of the heat-pretreated LSP. The influence of substrate concentration on the non-pretreated LSP enzymolysis was assessed, and the enzymolysis was found to obey the Haldane model with inhibition by LSP substrate. The initial concentration of non-pretreated LSP was inferred theoretically to be 11.07 g/L in order to avoid substrate inhibition. On the other hand, Chrastil model was fitted and the diffusion resistance constant values were in the range of 0.5-0.6 for the diffusion-controlled encounter of enzyme and substrate, implying that diffusion was a rate-limiting step. The heat-pretreatment at 60 °C for 60 min could increase the DH of the LSP, which enhanced the efficiency of the enzymolysis by papain.