Production of chitooligosaccharides and their potential applications in medicine

Machine learning reveals novel compound for the improved production of chitooligosaccharides in Escherichia coli

In order to improve predictability of outcome and reduce costly rounds of trial-and-error, machine learning models have been of increasing importance in the field of synthetic biology. Besides applications in predicting genome annotation, process parameters and transcription initiation frequency, such models have also been of help for pathway optimization. The latter is a common strategy in metabolic engineering and improves the production of a desirable compound by optimizing enzyme expression levels of the production pathway. However, engineering steps might not lead to sufficient improvement, and bottlenecks may remain hidden among the hundreds of metabolic reactions occurring in a living cell, especially if the production pathway is highly interconnected with other parts of the cell's metabolism. Here, we use the synthesis of chitooligosaccharides (COS) to show that the production from such complex pathways can be improved by using machine learning models and feature importance analysis to find new compounds with an impact on COS production. We screened Escherichia coli libraries of engineered transcription regulators with an expected broad range of metabolic diversity and trained several machine learning models to predict COS production titers. Subsequent feature analysis led to the finding of iron, whose addition we could show improved COS production in vivo up to two-fold. Additionally, the analysis revealed important clues for future engineering steps.

Analysis, Properties, and Applications of Insect-Derived Chitosan: A Sustainable Path to Functional Polysaccharide Materials

Chitin and its deacetylated derivative, chitosan, are biopolymers of significant interest due to their biocompatibility, biodegradability, and wide-ranging applications in biomedical, environmental, and industrial fields. The exploitation of crustaceans as the traditional source of chitosan raises concerns about overfishing and ecological sustainability. Modern insect farming, in contrast, offers advantages such as a circular insect-based economy leading to a reduced carbon footprint. This review explores the potential of insect-derived chitosan as an alternative, emphasizing its environmental benefits during production, functional properties, and potential applications. Several aspects of key analytical techniques for chitin and chitosan characterization, including photometric, chromatographic, and spectroscopic methods, are also discussed. The review underscores the versatility of insect-derived chitosan in biomedical applications, including wound healing and drug delivery, as well as its potential in agriculture, packaging, and wastewater treatment.

Chitosan: An overview of its properties, solubility, functional technologies, food and health applications

The properties and potential applications of chitosan have attracted a lot of interest; each year, the number of publications and patents based on this polymer increases. A significant obstacle to the application of chitosan is its limited solubility in basic and neutral solutions. The fact that chitosan is a series of molecules with variations in size, content, and monomer distribution rather than a single polymer with a well-defined structure and a natural origin is another significant barrier. Some of the claimed biological qualities are distinct, and these characteristics have a fundamental effect on the polymer's technological and biological performance. The poor solubility of the polymer can be improved by chitosan chemistry, and in this assessment, we discuss the changes made to make chitosan more soluble and its possible uses. We concentrate on a few of the primary biological characteristics of chitosan and how they relate to the physicochemical characteristics of the polymer. The use of chitosan in the environmentally friendly manufacture of metallic nanoparticles as well as its usage as a booster for biocatalysts are two further applications of polymers that are linked to green processes that we revisit. This study also presents information about utilizing chitosan's technological advantages.

A bioactivity matrix for antimicrobial activities of chitosans: A review

Chitosans have prominent antimicrobial activities, inhibiting growth of both bacteria and fungi, but molecular structure-function relationships of these activities are still only partially understood. Structurally, chitosans differ in their degree of polymerization (DP), fraction of acetylation (FA), and pattern of acetylation (PA). How these structural parameters are influencing antimicrobial activities is still a matter of debate. A comprehensive screening of all pertinent reviews and original publications dealing with antimicrobial activities of chitosans published in five selected years from 2000 to 2020 was performed. This screening of 2929 publications in total yielded 134 original papers, that contained data suitable for a thorough analysis of the influence of DP and FA on chitosans' antimicrobial activities. Despite many differences between the studies, e.g. in the purity and quality of the chitosans, the microbial species, or the bioassay used, a partial consensus picture emerged. The strongest antimicrobial activity was observed for chitosans with a low to intermediate Mw. Larger polymers had lower activities, and chitosan oligomers were almost inactive. Less clearly, a trend was observed for decreasing activities with increasing FA. Possible reasons for identifying only a partial rather than a comprehensive consensus picture are discussed.

Genome-Wide Mining of Chitinase Diversity in the Marine Diatom Thalassiosira weissflogii and Functional Characterization of a Novel GH19 Enzyme

Chitin represents a globally abundant marine polymer with significant ecological and biotechnological value. β-chitin is an important carbon fixation product of diatoms and has a greater range of applications than α- and γ-chitin. However, there has been a paucity of research on the characterization of chitin-related enzymes from β-chitin producers. In this study, we performed a genome-wide identification of 38 putative chitinase genes in Thalassiosira weissflogii, a key producer of β-chitin. Through comprehensive analyses of phylogenetic relationships, conserved motifs, structural domains, and subcellular localization predictions, we revealed that T. weissflogii possesses evolutionarily distinct GH18 and GH19 chitinase families exhibiting unique motif and domain configurations. Subcellular localization predictions showed that most TwChis were presumed to be located in the chloroplast, with a few being present in the nucleus and extracellular. The enzymatic activity of TwChi2, a GH19 chitinase, showed that TwChi2 was a member of exochitinase (EC 3.2.1.201) with strong thermal stability (40 °C) and broad substrate adaptability of hydrolyzing bipolymer, 1% and 5% colloidal chitin, α-chitin and β-chitin. Altogether, we analyzed the chitinase gene family and characterized a highly active exochitinase from T. weissflogii, which can catalyze the degradation of both chitin polymers and chitin oligosaccharides. The relevant results lay a foundation for the internal regulation mechanism of chitin metabolism in diatoms and provide a candidate enzyme for the green industrial preparation of high-value chitin oligosaccharides.

Chitosan: A versatile polymer for enhancing plant bioactive accumulation, managing plant diseases, and advancing food preservation technologies

Chitosan is a versatile biopolymer composed of N-acetyl D-glucosamine and D-glucosamine units linked by β-(1→4) glycosidic bonds. It is known for its diverse biological applications, which include antimicrobial, antioxidant, antitumor, immunomodulatory, immunoadjuvant, and metal ion chelating abilities. Despite these benefits, the complexity of chitosan's structure limits its use in specific applications, particularly in scalability, solubility, and formulation stability. This review examines chitosan's role in food technology, agriculture, and tissue culture, focusing on its potential to enhance the accumulation of secondary metabolites and its applications in nanotechnology. A comprehensive search of databases, including PubMed, Scopus, and Google Scholar, was conducted to gather relevant literature. Chitosan is used in food technology to preserve seafood and meat, package them, and monitor degradation. Its role in improving crop productivity and plant disease management and promoting growth in both ex-vitro and in-vitro conditions has been discussed, as have chitosan-based nanoformulations as plant growth promoters and biocides. Further research could unlock chitosan's potential to enhance food security, environmental sustainability, and sustainable agriculture. Future research should be directed toward enabling chitosan's broader applications beyond food technology and agriculture. An integrated effort among academic institutions, research centres, and regulatory bodies is needed to bridge the gap between innovation and practical implementation. These efforts include joint research initiatives, policy framework development, capacity building, public-private partnerships, harmonization of standards, and fostering collaboration between industries and regulatory agencies. These efforts aim to validate new technologies, establish shared databases, streamline approval processes, and ensure research outcomes are translatable into regulatory and commercial frameworks.

Heparin-binding of the human chitinase-like protein YKL-40 is allosterically modified by chitin oligosaccharides

The chitinase-like protein YKL-40 (CHI3L1) has been implicated in the pathophysiology of inflammation and cancer. Recent studies highlight the growing interest in targeting and blocking the activity of YKL-40 to treat cancer. Some of those targeting-strategies have been developed to directly block the heparin-affinity of YKL-40 with promising results. This study explores how short chain chitooligosaccharides (ChOS) affect the heparin-binding affinity of YKL-40. Our findings reveal that ChOS act as allosteric effectors, decreasing the heparin-binding affinity of YKL-40 in a size- and dose-dependent manner. Our results provide insights into the heparin affinity of YKL-40 and how ChOS can be used to target the heparin activity of YKL-40 in diseases. Since ChOS has many beneficial properties, such as being non-toxic and biodegradable, these results provide intriguing opportunities for applying them as allosteric effectors of the heparin-binding affinity of YKL-40.

Icariin-loaded chitosan/β-glycerophosphate thermosensitive hydrogel enhanced infection control and bone regeneration in canine with infectious bone defects

Faced with infectious bone defects, the development of a thermosensitive hydrogel containing icariin (ICA) represents a promising therapeutic strategy targeting infection control and bone regeneration. In this study, we prepared and evaluated the physicochemical properties, in vitro and in vivo drug release, antimicrobial activity, anti-inflammatory properties, and bone repair effects of ICA/Chitosan/β-Glycerophosphate (ICA/CTS/β-GP) thermosensitive hydrogel. Our findings demonstrate that the ICA/CTS/β-GP thermosensitive hydrogel undergoes a liquid-to-gel transition at body temperature, which is crucial for maintaining local drug release at the defect site. Additionally, the hydrogel exhibited sustained release of ICA over 28 days, showing high antimicrobial activity against Staphylococcus aureus and good biocompatibility in blood compatibility tests. In a canine model of infectious bone defects, the ICA/CTS/β-GP thermosensitive hydrogel showed effective infection control and modulated inflammation, vascular formation, and bone factor expression, while also activating the Wnt/β-catenin signaling pathway. In conclusion, the ICA/CTS/β-GP thermosensitive hydrogel could control infection and repair bone tissue. Its antimicrobial and osteogenic properties provide hope for its clinical application.

Dissecting and optimizing bioactivities of chitosans by enzymatic modification

Chitosans are versatile biopolymers with antimicrobial and plant-strengthening properties relevant to agriculture. However, a limited understanding of molecular structure-function relationships and cellular modes of action of chitosans hampers the development of effective chitosan-based agro-biologics. We partially hydrolyzed a chitosan polymer (degree of polymerization DP 800, fraction of acetylation FA 0.2) using acetic acid, a GH18 chitinase, or a GH8 chitosanase. All hydrolysates contained mixtures of chitosan oligomers and small polymers, but their composition in terms of DP, FA, and pattern of acetylation (PA) differed greatly. Importantly, chitinase products had mostly deacetylated residues at their ends, flanking mostly deacetylated residues, and vice versa for chitosanase products, while the products of acid hydrolysis had random PA. Acid hydrolysis did not significantly change antifungal and antibacterial activities. In contrast, chitinase hydrolysis slightly increased antibacterial, and chitosanase almost abolished antifungal activity. Elicitor and priming activities in the plant Arabidopsis were unchanged by acid, destroyed by chitinase, and increased by chitosanase hydrolysis. Transcriptomic analysis revealed that the chitosan polymer strongly induced genes involved in photosynthesis, while the chitosanase hydrolysate strongly induced genes involved in disease resistance. Clearly, different bioactivities require different chitosans, and enzymatic modification can fine-tune these activities as required for different agricultural products.

Combinatorial metabolic engineering of Escherichia coli for de novo production of structurally defined and homogeneous Amino oligosaccharides

Amino oligosaccharides (AOs) possess various biological activities and are valuable in the pharmaceutical, food industries, and agriculture. However, the industrial manufacturing of AOs has not been realized yet, despite reports on physical, chemical, and biological approaches. In this study, the de novo production of chitin oligosaccharides (CHOS), a type of structurally defined AOs, was achieved in Escherichia coli through combinatorial pathway engineering. The most suitable glycosyltransferase for CHOS production was found to be NodCL from Mesorhizobium Loti. Then, by knocking out the nagB gene to block the flow of N-acetyl-d-glucosamine (NAG) to the glycolytic pathway in E. coli and adjusting the copy number of NodCL-coding gene, the CHOS yield was increased by 6.56 times. Subsequently, by introducing of UDP-N-acetylglucosamine (UDP-GlcNAc) salvage pathway for and optimizing fermentation conditions, the yield of CHOS reached 207.1 and 468.6 mg/L in shake-flask cultivation and a 5-L fed-batch bioreactor, respectively. Meanwhile, the concentration of UDP-GlcNAc was 91.0 mg/L, the highest level reported in E. coli so far. This study demonstrated, for the first time, the production of CHOS with distinct structures in plasmid-free E. coli, laying the groundwork for the biosynthesis of CHOS and providing a starting point for further engineering and commercial production.

Study on Fabrication and Properties of Polyvinyl Alcohol/Chitosan Nanofibers Created from Aqueous Solution with Acetic Acid and Ethanol by the Electrospinning Method

The development of nanofibers with incorporated biologically active molecules with a targeted mode of action is a current research trend. Potential materials for the development of such systems include poly(vinyl alcohol) (PVA) and chitosan (CS) nanofibers, which are traditionally fabricated by the electrospinning of aqueous solutions of these polymers with acetic acid. To improve drug integration, ethanol was added to the binary-solvent system. This results in several important data: noticeable shifts in the solvent system's solubility parameter, the interaction of the various component forces, and optical and rheological properties of the PVA-CS solution. The use of ethanol in the electrospun solution also contributes to adjusting the solubility parameters of the solution in the Teas graph, maintaining the "fh - fd" in the optimal region for the fabrication of PVA-CS nanofibers. Increasing the efficiency of PVA-CS nanofiber fabrication by electrospinning is quite difficult due to the requirements of solution parameters, technological parameters, and environmental parameters; however, this efficiency was increased in this work by 2 to 3 times with a more optimal PVA-CS nanofiber morphology. These results demonstrate that aqueous solution containing 4% PVA, 3% CS, 15% ethanol, and 45% acetic acid is optimal for increasing the nanofiber fabrication productivity, improving the morphology and diameter of PVA-CS nanofibers without changing in chemical bonds. The XRD spectrum revealed that the alterations in the crystal lattice and diameter of the PVA-CS nanofibers led to the variation in their thermal and tensile properties.

Marine chitinase AfChi: green defense management against Colletotrichum gloeosporioides and anthracnose

Anthracnose disease, caused by the Colletotrichum gloeosporioides species, affects vegetables, fruits, pulses, and cereals, leading to significant economic losses worldwide. Although many synthetic fungicides are used to control this pathogen, eco-friendly biological alternatives are gaining popularity. This study focuses on isolating and purifying chitinase ( Af Chi)from a marine bacterium and testing its antifungal efficacy against C. gloeosporioides spore germination by targeting the chitin in the fungal cell wall. The chitinase was purified from a marine bacterium A. faecalis from the Arabian Sea and had a molecular mass of 45 kDa and a specific activity of 84.6 U/mg. Af Chi worked best at 50 °C and pH 7.0 in Tris HCl buffer. Na+ ion was the highest cofactor, highlighting the halophilic nature of this chitinase. K+, Ca2+, Cu2+, Mg2+, Mn2+, and EDTA also increased activity, while Fe3+, Zn2+, Co2+, and Pb2+ decreased it. The Km and Vmax values were 1.87 µg/mL and 17.45 U/mL, respectively. Purified Af Chi at 10 mg/mL completely inhibited spore germination within 8 h and reduced the size of the spores.

Chitooligosaccharides improves intestinal mucosal immunity and intestinal microbiota in blue foxes

Objective

Gut health is critical to the health of the host. This study was conducted to investigate the effects of Chitooligosaccharides (COS) on intestinal morphology, intestinal barrier, intestinal immunity and cecum microbiota of blue foxes.

Methods

Seventy-two 125-day-old blue foxes were randomly divided into basal diet (BD) group, 200 ppm COS1 (1.5 kDa) group and 200 ppm COS2 (3 kDa) group for 8 weeks.

Results

We elucidated that dietary COS1 supplementation promoted the development of intestinal villus morphology in blue foxes. Importantly, COS1 increased the number of goblet cells in duodenum, jejunum and ileum by 27.71%, 23.67%, 14.97% and S-IgA secretion in duodenum, jejunum and ileum by 71.59% and 38.56%, and up-regulate the expression of Occludin and ZO-1 by 50.18% and 148.62%, respectively. Moreover, COS1 promoted the pro-inflammatory and anti-inflammatory balance of small intestinal mucosa, and increased the diversity of cecum microbiota of blue foxes, especially Lactobacillus_agilis and Lactobacillus_murinus, and up-regulated the signaling pathways related to polysaccharide decomposition and utilization.

Conclusion

Here, we present dietary COS1 (1.5 kDa) can promote intestinal villus development, enhance intestinal barrier function, regulate intestinal immune balance and cecum microbiota homeostasis.

Multiple omics integration analysis reveals the regulatory effect of chitosan oligosaccharide on testicular development

Infertility is a global health problem affecting millions of people of reproductive age worldwide, with approximately half caused by males. Chitosan oligosaccharide (COS) has strong antioxidant capacity, but its impact on the male reproductive system has not been effectively evaluated. To address this, we integrated RNA-seq, serum metabolomics and intestinal 16 S rDNA analysis to conduct a comprehensive investigation on the male reproductive system. The results showed that COS has potential targets for the treatment of oligospermia, which can promote the expression of meiotic proteins DDX4, DAZL and SYCP1, benefit germ cell proliferation and testicular development, enhance antioxidant capacity, and increase the expression of testicular steroid proteins STAR and CYP11A1. At the same time, COS can activate PI3K-Akt signaling pathway in testis and TM3 cells. Microbiome and metabolomics analysis suggested that COS alters gut microbial community composition and cooperates with serum metabolites to regulate spermatogenesis. Therefore, COS promotes male reproduction by regulating intestinal microorganisms and serum metabolism, activating PI3K-Akt signaling pathway, improving testicular antioxidant capacity and steroid regulation.

Marine Bioactive Compounds with Functional Role in Immunity and Food Allergy

Food allergy, referred to as the atypical physiological overreaction of the immune system after exposure to specific food components, is considered one of the major concerns in food safety. The prevalence of this emerging worldwide problem has been increasing during the last decades, especially in industrialized countries, being estimated to affect 6-8% of young children and about 2-4% of adults. Marine organisms are an important source of bioactive substances with the potential to functionally improve the immune system, reduce food allergy sensitization and development, and even have an anti-allergic action in food allergy. The present investigation aims to be a comprehensive report of marine bioactive compounds with verified actions to improve food allergy and identified mechanisms of actions rather than be an exhaustive compilation of all investigations searching beneficial effects of marine compounds in FA. Particularly, this research highlights the capacity of bioactive components extracted from marine microbial, animal, algae, and microalgae sources, such as n-3 long-chain polyunsaturated fatty acids (LC-PUFA), polysaccharide, oligosaccharide, chondroitin, vitamin D, peptides, pigments, and polyphenols, to regulate the immune system, epigenetic regulation, inflammation, and gut dysbiosis that are essential factors in the sensitization and effector phases of food allergy. In conclusion, the marine ecosystem is an excellent source to provide foods with the capacity to improve the hypersensitivity induced against specific food allergens and also bioactive compounds with a potential pharmacological aptitude to be applied as anti-allergenic in food allergy.

High Degree of Polymerization of Chitin Oligosaccharides Produced from Shrimp Shell Waste by Enrichment Microbiota Using Two-Stage Temperature-Controlled Technique of Inducing Enzyme Production and Metagenomic Analysis of Microbiota Succession

The direct enzymatic conversion of untreated waste shrimp and crab shells has been a key problem that plagues the large-scale utilization of chitin biological resources. The microorganisms in soil samples were enriched in two stages with powdered chitin (CP) and shrimp shell powder (SSP) as substrates. The enrichment microbiota XHQ10 with SSP degradation ability was obtained. The activities of chitinase and lytic polysaccharide monooxygenase of XHQ10 were 1.46 and 54.62 U/mL. Metagenomic analysis showed that Chitinolyticbacter meiyuanensis, Chitiniphilus shinanonensis, and Chitinimonas koreensis, with excellent chitin degradation performance, were highly enriched in XHQ10. Chitin oligosaccharides (CHOSs) are produced by XHQ10 through enzyme induction and two-stage temperature control technology, which contains CHOSs with a degree of polymerization (DP) more significant than ten and has excellent antioxidant activity. This work is the first study on the direct enzymatic preparation of CHOSs from SSP using enrichment microbiota, which provides a new path for the large-scale utilization of chitin bioresources.

Exploiting specific properties of squid pens for the preparation of oligochitosan hydrochloride

Herein, we describe in first the application of squid pens for the preparation of pharmaceutical-grade oligochitosan hydrochloride with the physicochemical characteristics corresponding with the requirements of the European Pharmacopoeia. It is shown that the use of specific properties of squid pens as a source of parent chitosan allows preparing the product with a high yield at relatively moderate process conditions used for squid pens treatments and chitosan depolymerization.

Modulating intestinal health: Impact of chitooligosaccharide molecular weight on suppressing RAGE expression and inflammatory response in methylglyoxal-induced advanced glycation end-products

The accumulation of methylglyoxal (MGO) produced in high-temperature processed foods and excessive production in the body contributes to intestinal barrier dysfunction. In this study, we investigated the effects of chitooligosaccharides (COSs) of different molecular weights (<1 kDa, 1-3 kDa, 3-5 kDa, 5-10 kDa, and >10 kDa) on MGO-induced intestinal barrier dysfunction. We investigated the effect of COSs on inhibiting intracellular MGO accumulation/MGO-derived AGEs production and regulating the receptor for AGE (RAGE)-mediated downstream protein expression, including proteins related to apoptosis and inflammation, intestinal barrier integrity, and paracellular permeability. Pretreatment with COSs ameliorated MGO-induced increased RAGE protein expression, activation of apoptotic cascade/inflammatory response, loss of intestinal epithelial barrier integrity, and increased paracellular permeability, ameliorating intestinal dysfunction through MGO scavenging. 1-3 kDa COSs most effectively ameliorated MGO-induced intestinal dysfunction. Our results suggest the potential of COSs in improving intestinal health by ameliorating intestinal barrier dysfunction by acting as an MGO scavenger and highlighting the need for the optimization of the molecular weight of COSs to optimize its protective effects.

Alternative processes to produce chitin, chitosan, and their oligomers

Sustainable recovery of chitin and its derivatives from shellfish waste will be achieved when the industrial production of these polymers is achieved with a high control of their molecular structure, low costs, and acceptable levels of pollution. Therefore, the conventional chemical method for obtaining these biopolymers needs to be replaced or optimized. The goal of the present review is to ascertain what alternative methods are viable for the industrial-scale production of chitin, chitosan, and their oligomers. Therefore, a detailed review of recent literature was undertaken, focusing on the advantages and disadvantages of each method. The analysis of the existing data allows suggesting that combining conventional, biological, and alternative methods is the most efficient strategy to achieve sustainable production, preventing negative impacts and allowing for the recovery of high added-value compounds from shellfish waste. In conclusion, a new process for obtaining chitinous materials is suggested, with the potential of reducing the consumption of reagents, energy, and water by at least 1/10, 1/4, and 1/3 part with respect to the conventional process, respectively.

The rotamer of the second-sphere histidine in AA9 lytic polysaccharide monooxygenase is pH dependent

Lytic polysaccharide monooxygenases (LPMOs) catalyze a reaction that is crucial for the biological decomposition of various biopolymers and for the industrial conversion of plant biomass. Despite the importance of LPMOs, the exact molecular-level nature of the reaction mechanism is still debated today. Here, we investigated the pH-dependent conformation of a second-sphere histidine (His) that we call the stacking histidine, which is conserved in fungal AA9 LPMOs and is speculated to assist catalysis in several of the LPMO reaction pathways. Using constant-pH and accelerated molecular dynamics simulations, we monitored the dynamics of the stacking His in different protonation states for both the resting Cu(II) and active Cu(I) forms of two fungal LPMOs. Consistent with experimental crystallographic and neutron diffraction data, our calculations suggest that the side chain of the protonated and positively charged form is rotated out of the active site toward the solvent. Importantly, only one of the possible neutral states of histidine (HIE state) is observed in the stacking orientation at neutral pH or when bound to cellulose. Our data predict that, in solution, the stacking His may act as a stabilizer (via hydrogen bonding) of the Cu(II)-superoxo complex after the LPMO-Cu(I) has reacted with O2 in solution, which, in fine, leads to H2O2 formation. Also, our data indicate that the HIE-stacking His is a poor acid/base catalyst when bound to the substrate and, in agreement with the literature, may play an important stabilizing role (via hydrogen bonding) during the peroxygenase catalysis. Our study reveals the pH titration midpoint values of the pH-dependent orientation of the stacking His should be considered when modeling and interpreting LPMO reactions, whether it be for classical LPMO kinetics or in industry-oriented enzymatic cocktails, and for understanding LPMO behavior in slightly acidic natural processes such as fungal wood decay.

3D bioprinting approaches for spinal cord injury repair

Regenerative healing of spinal cord injury (SCI) poses an ongoing medical challenge by causing persistent neurological impairment and a significant socioeconomic burden. The complexity of spinal cord tissue presents hurdles to successful regeneration following injury, due to the difficulty of forming a biomimetic structure that faithfully replicates native tissue using conventional tissue engineering scaffolds. 3D bioprinting is a rapidly evolving technology with unmatched potential to create 3D biological tissues with complicated and hierarchical structure and composition. With the addition of biological additives such as cells and biomolecules, 3D bioprinting can fabricate preclinical implants, tissue or organ-like constructs, andin vitromodels through precise control over the deposition of biomaterials and other building blocks. This review highlights the characteristics and advantages of 3D bioprinting for scaffold fabrication to enable SCI repair, including bottom-up manufacturing, mechanical customization, and spatial heterogeneity. This review also critically discusses the impact of various fabrication parameters on the efficacy of spinal cord repair using 3D bioprinted scaffolds, including the choice of printing method, scaffold shape, biomaterials, and biological supplements such as cells and growth factors. High-quality preclinical studies are required to accelerate the translation of 3D bioprinting into clinical practice for spinal cord repair. Meanwhile, other technological advances will continue to improve the regenerative capability of bioprinted scaffolds, such as the incorporation of nanoscale biological particles and the development of 4D printing.

Expression profiles and characterization of microRNAs responding to chitin in Arthrobotrys oligospora

Extracellular proteases, such as chitinases secreted by Arthrobotrys oligospora (A. oligospora), play a crucial role in the process of nematode infection. However, post-transcriptional regulation of gene expression involving microRNAs (miRNAs) in A. oligospora remains scarcely described. Hereto, transcriptome sequencing was carried out to analyze the expression profiles of chitin-responsive miRNAs in A. oligospora. Based on the RNA-seq data, the differential expression of miRNAs (DEmiRNAs) in response to chitin was screened, identified and characterized in A. oligospora. Meanwhile, the potential target genes were predicted by the online tools miRanda and Targetscan, respectively. Furthermore, the interaction of DEmiRNA with it's target gene was validated by a dual-luciferase reporter assay system. Among 85 novel miRNAs identified, 25 miRNAs displayed significant differences in expression in A. oligospora in response to chitin. Gene Ontology (GO) analysis showed that the potential genes targeted by DEmiRNAs were enriched in the biological processes such as bio-degradation, extracellular components and cell cycle. KEGG analysis revealed that the target genes were mainly involved in Hippo, carbon and riboflavin metabolic pathway. Outstandingly, chitinase AOL_s00004g379, which is involved in the hydrolysis metabolic pathway of chitin, was confirmed to be a target gene of differential miR_70. These findings suggest that chitin-responsive miRNAs are involved in the regulation of cell proliferation, predator hyphae growth and chitinase expression through the mechanisms of post-transcriptional regulation, which provides a new perspective to the molecular mechanisms underlying miRNAs-mediated control of gene expression in A. oligospora.

Microbes as a tool for the bioremediation of fish waste from the environment and the production of value-added compounds: a review

Fish are the most edible protein source worldwide and generate several remnants such as scales, viscera, head, bone, and skin. Fish wastes are not disposed of properly, which adversely affects the environment, especially the water bodies where fish processing industries dispose of their waste. Fish waste mainly contains nitrogen, oil, fat, salts, heavy metals, and organic compounds, which increase the biological oxygen demand and chemical oxygen demand. Fish waste can degrade in various ways, such as physicochemical or by enzymatic action, but using microbes is an environmentally friendly approach that can provide valuable compounds such as products such as collagen, chitin, minerals, and fish protein concentrates. This review is designed to focus on the suitability of microbes as tools for fish waste degradation and the production of certain associated. This study also provides insight into the production of other compounds such as protease, chitinase, and chitin applicability of these products. After processing, fish waste as a microbial growth media for enzyme production since microorganisms synthesize enzymes such as proteases, protein hydrolysates, lipids, and chitinase, which have broader applications in the pharmaceutical, cosmetic, biomedical material, and food processing industries.

Maximizing crustaceans (shrimp, crab, and lobster) by-products value for optimum valorization practices: A comparative review of their active ingredients, extraction, bioprocesses and applications

BACKGROUND

The processing of the three major crustaceans (shrimp, lobster, and crab) is associated with inevitable by-products, high waste disposal costs, environmental and human health issues, loss of multiple biomaterials (chitin, protein hydrolysates, lipids, astaxanthin and minerals). Nowadays, these bioresources are underutilized owing to the lack of effective and standardized technologies to convert these materials into valued industrial forms.

AIM OF REVIEW

This review aims to provide a holistic overview of the various bioactive ingredients and applications within major crustaceans by-products. This review aims to compare various extraction methods in crustaceans by-products, which will aid identify a more workable platform to minimize waste disposal and maximize its value for best valorization practices.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The fully integrated applications (agriculture, food, cosmetics, pharmaceuticals, paper industries, etc.) of multiple biomaterials from crustaceans by-products are presented. The pros and cons of the various extraction methods, including chemical (acid and alkali), bioprocesses (enzymatic or fermentation), physical (microwave, ultrasound, hot water and carbonic acid process), solvent (ionic liquids, deep eutectic solvents, EDTA) and electrochemistry are detailed. The rapid development of corresponding biotechnological attempts present a simple, fast, effective, clean, and controllable bioprocess for the comprehensive utilization of crustacean waste that has yet to be applied at an industrial level. One feasible way for best valorization practices is to combine innovative extraction techniques with industrially applicable technologies to efficiently recover these valuable components.

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.

Valorization of shrimp processing waste-derived chitosan into anti-inflammatory chitosan-oligosaccharides (CHOS)

Bioconversion of chitosan into soluble anti-inflammatory chitosan oligosaccharides (CHOS) using a Bacillus chitosanase, BsCsn46A, was investigated, including food-grade approaches. After 48 h of enzymatic reaction, most of the final products were dimers and trimers. None of the CHOS products showed toxicity to human fibroblasts. Analysis of CHOS bioactivity against LPS-induced inflammation of human macrophages indicated that CHOS generated from different bioconversion processes have anti-inflammatory activity, the magnitude of which depends on the type of substrate and production process. Both lactic acid and HCl can be used to dissolve chitosan; however, the product generated from lactic acid solution was highly hygroscopic after lyophilization, hence not suitable for long-term storage. Downstream processes, i.e., centrifugation and filtration, affect its anti-inflammatory activity. Analysis of standard CHOS with known structure showed that an acetyl group at the reducing end and the degree of polymerization (DP) are critical for biological activity. Importantly, when applied at levels above the optimal concentrations, certain standard CHOS and CHOS mixtures could induce inflammation. These results support the potential of CHOS as anti-inflammatory agents but reveal batch-to-batch variation and possible side effects, indicating that careful quality assurance of CHOS preparations is essential.

Chitin, chitosan and chitooligosaccharides as potential growth promoters and immunostimulants in aquaculture: A comprehensive review

There is a stable growth in aquaculture production to avoid seafood scarcity. The usage of eco-friendly feed additives is not only associated with aquatic animal health but also reduces the risk of deleterious effects to the environment and consumers. Aquaculture researchers are seeking dietary solutions to improve the growth performance and yield of target organisms. A wide range of naturally derived compounds such as probiotics, prebiotics, synbiotics, complex carbohydrates, nutritional factors, herbs, hormones, vitamins, and cytokines was utilized as immunostimulants in aquaculture. The use of polysaccharides derived from natural resources, such as alginate, agar, laminarin, carrageenan, fucoidan, chitin, and chitosan, as supplementary feed in aquaculture species has been reported. Polysaccharides are prebiotic substances which are enhancing the immunity, disease resistance and growth of aquatic animals. Further, chitin (CT), chitosan (CTS) and chitooligosaccharides (COS) were recognized for their biodegradable properties and unique biological functions. The dietary effects of CT, CTS and COS at different inclusion levels on growth performance, immune response and gut microbiota in aquaculture species has been reviewed. The safety regulations, challenges and future outlooks of CT, CTS and COS in aquatic animals have been discussed in this review.

Effect of Soft Preheating of Bovine Serum Albumin on the Complexation with Oligochitosan: Structure and Conformation of BSA in the Complex

Phase analysis, spectroscopic, and light scattering methods are applied to investigate the peculiarities of the interaction of oligochitosan (OCHI) with native and preheated bovine serum albumin (BSA) as well as the conformational and structural changes of BSA in BSA/OCHI complex. As shown, untreated BSA binds with OCHI mainly forming soluble electrostatic nanocomplexes, with the binding causing an increase in BSA helicity without a change in the local tertiary structure and thermal stability of BSA. In contrast, soft preheating at 56 °C enhances the complexation of BSA with OCHI and slightly destabilizes the secondary and local tertiary structures of BSA within the complex particles. Preheating at 64 °C (below the irreversible stage of BSA thermodenaturation) leads to further enhancement in the complexation and formation of insoluble complexes stabilized by both Coulomb forces and hydrophobic interactions. The finding can be promising for the preparation of biodegradable BSA/chitosan-based drug delivery systems.

Chitosan oligosaccharide suppresses osteosarcoma malignancy by inhibiting CEMIP via the PI3K/AKT/mTOR pathway

Osteosarcoma is a malignant bone tumor that is prone to metastasize early and primarily affects children and adolescents. Cell migration-inducing protein (CEMIP) plays a crucial role in the progression and malignancy of various tumor diseases, including osteosarcoma. Chitosan oligosaccharide (COS), an oligomer isolated from chitin, has been found to have significant anti-tumor activity in various cancers. This study investigates the effects of COS on CEMIP expression in osteosarcoma and explores the underlying mechanism. In present study, in vitro experiments were conducted to confirm the inhibitory activity of COS on human osteosarcoma cells. Our results demonstrate that COS possesses inhibitory effects against human osteosarcoma cells and significantly suppresses CEMIP expression in vitro. Next, we studied the inhibition of the expression of CEMIP by COS and then performed bioinformatics analysis to explore the potential inhibitory mechanism of COS against signaling pathways involved in regulating CEMIP expression. Bioinformatics analysis predicted a close association between the PI3K signaling pathway and CEMIP expression and that the inhibitory effect of COS on CEMIP expression may be related to PI3K signaling pathway regulation. The results of this study show that COS treatment significantly inhibits CEMIP expression and the PI3K/AKT/mTOR signaling pathway, as observed both in vitro and in vivo. This study demonstrates that COS could inhibit the expression of CEMIP, which is closely related to osteosarcoma malignancy. This inhibitory effect may be attributed to the inhibition of the PI3K/AKT/mTOR signaling pathway in vitro and in vivo.

N-acetyl-d-glucosamine-based oligosaccharides from chitin: Enzymatic production, characterization and biological activities

Chitin, the second most abundant biopolymer, possesses diverse applications in the food, agricultural, and pharmaceutical industries due to its functional properties. However, the potential applications of chitin are limited owing to its high crystallinity and low solubility. N-acetyl chitooligosaccharides and lacto-N-triose II, the two types of GlcNAc-based oligosaccharides, can be obtained from chitin by enzymatic methods. With their lower molecular weights and improved solubility, these two types of GlcNAc-based oligosaccharides display more various beneficial health effects when compared to chitin. Among their abilities, they have exhibited antioxidant, anti-inflammatory, anti-tumor, antimicrobial, and plant elicitor activities as well as immunomodulatory and prebiotic effects, which suggests they have the potential to be utilized as food additives, functional daily supplements, drug precursors, elicitors for plants, and prebiotics. This review comprehensively covers the enzymatic methods used for the two types of GlcNAc-based oligosaccharides production from chitin by chitinolytic enzymes. Moreover, current advances in the structural characterization and biological activities of these two types of GlcNAc-based oligosaccharides are summarized in the review. We also highlight current problems in the production of these oligosaccharides and trends in their development, aiming to offer some directions for producing functional oligosaccharides from chitin.

Toxicological, hepato-renal, endocrine disruption, oxidative stress and immunohistopathological responses of chitosan capped gold nanocomposite on Biomphalaria alexandrina snails

The present investigation aimed to synthesize chitosan‑gold nanocomposites (Ch-AuNPs) with gamma radiation, then to evaluate its toxic effect on the freshwater snails Biomphalaia alexandrina. Results showed that Ch-AuNPs is spherical shaped with average size 12 nm. It had a toxic effect against B. alexandrina snails with LC50 20.43 mg/l. Exposure of B. alexandrina snails to LC10 7.51 or LC25 13.63 mg/l of Ch-AuNPs, reduced the survival, reproductive and fecundity rates; total protein and albumin; both testosterone (T) and 17β Estradiol (E) levels; SOD and CAT activities of exposed snails while increased the activities of transaminases (AST & ALT), uric acid, creatinine, TAC and MDA levels compared to the control group. Results were supported by histopathological and immunohistopathological alterations of the digestive and hermaphrodite glands. In conclusion B. alexandrina could be used as a model to screen the negative impact of nanomaterials. Also, Ch-AuNPs could be used as a molluscicidal agent.

Isolation, biochemical characterization, and genome sequencing of two high-quality genomes of a novel chitinolytic Jeongeupia species

Chitin is the second most abundant polysaccharide worldwide as part of arthropods' exoskeletons and fungal cell walls. Low concentrations in soils and sediments indicate rapid decomposition through chitinolytic organisms in terrestrial and aquatic ecosystems. The enacting enzymes, so-called chitinases, and their products, chitooligosaccharides, exhibit promising characteristics with applications ranging from crop protection to cosmetics, medical, textile, and wastewater industries. Exploring novel chitinolytic organisms is crucial to expand the enzymatical toolkit for biotechnological chitin utilization and to deepen our understanding of diverse catalytic mechanisms. In this study, we present two long-read sequencing-based genomes of highly similar Jeongeupia species, which have been screened, isolated, and biochemically characterized from chitin-amended soil samples. Through metabolic characterization, whole-genome alignments, and phylogenetic analysis, we could demonstrate how the investigated strains differ from the taxonomically closest strain Jeongeupia naejangsanensis BIO-TAS4-2T (DSM 24253). In silico analysis and sequence alignment revealed a multitude of highly conserved chitinolytic enzymes in the investigated Jeongeupia genomes. Based on these results, we suggest that the two strains represent a novel species within the genus of Jeongeupia, which may be useful for environmentally friendly N-acetylglucosamine production from crustacean shell or fungal biomass waste or as a crop protection agent.

Nondigestible Functional Oligosaccharides: Enzymatic Production and Food Applications for Intestinal Health

Nondigestible functional oligosaccharides are of particular interest in recent years because of their unique prebiotic activities, technological characteristics, and physiological effects. Among different types of strategies for the production of nondigestible functional oligosaccharides, enzymatic methods are preferred owing to the predictability and controllability of the structure and composition of the reaction products. Nondigestible functional oligosaccharides have been proved to show excellent prebiotic effects as well as other benefits to intestinal health. They have exhibited great application potential as functional food ingredients for various food products with improved quality and physicochemical characteristics. This article reviews the research progress on the enzymatic production of several typical nondigestible functional oligosaccharides in the food industry, including galacto-oligosaccharides, xylo-oligosaccharides, manno-oligosaccharides, chito-oligosaccharides, and human milk oligosaccharides. Moreover, their physicochemical properties and prebiotic activities are discussed as well as their contributions to intestinal health and applications in foods.

Novel Chitin Deacetylase from Thalassiosira weissflogii Highlights the Potential for Chitin Derivative Production

β-Chitin is an important carbon fixation product of diatoms, and is the most abundant nitrogen-containing polysaccharide in the ocean. It has potential for widespread application, but the characterization of chitin-related enzymes from β-chitin producers has rarely been reported. In this study, a chitin deacetylase (TwCDA) was retrieved from the Marine Microbial Eukaryote Transcriptome Sequencing Project (MMETSP) database and was heterologously expressed in vitro for functional analysis. The results showed that both the full-length sequence (TwCDA) and the N-terminal truncated sequence (TwCDA-S) had chitin deacetylase and chitinolytic activities after expression in Escherichia coli. High-performance liquid chromatography (HPLC) and gas chromatography–mass spectrometry (GC-MS) indicated that TwCDA and TwCDA-S could catalyze the deacetylation of oligosaccharide (GlcNAc)5. TwCDA had higher deacetylase activity, and also catalyzed the deacetylation of the β-chitin polymer. A dinitrosalicylic acid (DNS) assay showed that TwCDA-S had high chitinolytic activity for (GlcNAc)5, and the optimal reaction temperature was 35 °C. Liquid chromatography combined with time-of-flight mass spectrometry (LC-coTOF-MS) detected the formation of a N-acetylglucosamine monomer (C8H15NO6) in the reaction mixture. Altogether, we isolated a chitin deacetylase from a marine diatom, which can catalyze the deacetylation and degradation of chitin and chitin oligosaccharides. The relevant results lay a foundation for the internal regulation mechanism of chitin metabolism in diatoms and provide a candidate enzyme for the green industrial preparation of chitosan and chitin oligosaccharides.

A review on extraction of polysaccharides from crustacean wastes and their environmental applications

Disposal of biodegradable waste of seashells leads to an environmental imbalance. A tremendous amount of wastes produced from flourishing shell fish industries while preparing crustaceans for human consumption can be directed towards proper utilization. The review of the present study focuses on these polysaccharides from crustaceans and a few important industrial applications. This review aimed to emphasize the current research on structural analyses and extraction of polysaccharides. The article summarises the properties of chitin, chitosan, and chitooligosaccharides and their derivatives that make them non-toxic, biodegradable, and biocompatible. Different extraction methods of chitin, chitosan, and chitooligosaccharides have been discussed in detail. Additionally, this information outlines possible uses for derivatives of chitin, chitosan, and chitooligosaccharides in the environmental, pharmaceutical, agricultural, and food industries. Additionally, it is essential to the textile, cosmetic, and enzyme-immobilization industries. This review focuses on new, insightful suggestions for raising the value of crustacean shell waste by repurposing a highly valuable material.

Experimentally Induced Burns in Rats Treated with Innovative Polymeric Films Type Therapies

Considering that microbial resistance to antibiotics is becoming an increasingly widespread problem, burn management, which usually includes the use of topical antimicrobial dressings, is still facing difficulties regarding their efficiency to ensure rapid healing. In this context, the main objective of this research is to include new oxytetracycline derivatives in polymeric-film-type dressings for the treatment of wounds caused by experimentally induced burns in rats. The structural and physico-chemical properties of synthesized oxytetracycline derivatives and the corresponding membranes were analyzed by FT-IR and MS spectroscopy, swelling ability and biodegradation capacity. In vitro antimicrobial activity using Gram-positive and Gram-negative bacterial strains and pathogenic yeasts, along with an in vivo study of a burn wound model induced in Wistar rats, was also analyzed. The newly obtained polymeric films, namely chitosan-oxytetracycline derivative membranes, showed good antimicrobial activity noticed in the tested strains, a membrane swelling ratio (MSR) of up to 1578% in acidic conditions and a biodegradation rate of up to 15.7% on day 7 of testing, which are important required characteristics for the tissue regeneration process, after the production of a burn. The in vivo study proved that chitosan-derived oxytetracycline membranes showed also improved healing effects which contributes to supporting the idea of using them for the treatment of wounds caused by burns.

Application of depolymerized chitosan in crop production: A review

Currently, chitosan (CHT) is well known for its uses, particularly in veterinary and agricultural fields. However, chitosan's uses suffer greatly due to its extremely solid crystalline structure, it is insoluble at pH levels above or equal to 7. This has sped up the process of derivatizing and depolymerizing it into low molecular weight chitosan (LMWCHT). As a result of its diverse physicochemical as well as biological features which include antibacterial activity, non-toxicity, and biodegradability, LMWCHT has evolved into new biomaterials with extremely complex functions. The most important physicochemical and biological property is antibacterial, which has some degree of industrialization today. CHT and LMWCHT have potential due to the antibacterial and plant resistance-inducing properties when applied in crop production. This study has highlighted the many advantages of chitosan derivatives as well as the most recent studies on low molecular weight chitosan applications in crop development.

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.

Chitooligosaccharide-induced plant stress resistance

In nature, the production of plant stress resistance traits is often induced by extreme environmental conditions. Under extreme conditions, plants can be irreversibly damaged. Intervention with phytostimulants, however, can improve plant stress resistance without causing damage to the plants themselves, hence maintaining the production. For example, exogenous substances such as proteins and polysaccharides can be used effectively as phytostimulants. Chitooligosaccharide, a plant stimulant, can promote seed germination and plant growth and development, and improve plant photosynthesis. In this review, we summarize progress in the research of chitooligosaccharide-induced plant stress resistance. The mechanism and related experiments of chitooligosaccharide-induced resistance to pathogen, drought, low-temperature, saline-alkali, and other stresses are classified and discussed. In addition, we put forward the challenges confronted by chitooligosaccharide-induced plant stress resistance and the future research concept that requires multidisciplinary cooperation, which could provide data for the in-depth study of the effect of chitooligosaccharide on plants.

Optimization of Chitosan Extraction Process from Rapana venosa Egg Capsules Waste Using Experimental Design

New green and sustainable sources were chosen to obtain chitosan, an important material, with many applications in different fields. The present study is focused on egg capsules of Rapana venosa waste as raw material for chitosan oligomers. As previous studies revealed that chitosan extraction from this material takes place with a low yield, the present research aimed to optimize this step. A 2² experimental plan, with three replicates in the center, was proposed to investigate the influence of NaOH concentration and temperature on the yield extraction. After a primary analysis of the experimental data, a favorable temperature value was selected (90 °C) at which the total dissolution of the egg capsules was obtained. Then, at this temperature, the experimental plan was extended exploring the influence of the NaOH concentration on three levels (5, 6, and 7%) and the extraction duration on two levels (60 and 85 min). Based on all experimental data, a neural model was obtained and validated. The neural model was used to maximize the yield, applying Genetic Algorithm (GA) implemented in Matlab^®. The resulting optimal solution is: NaOH concentration 6.47%, temperature 90 °C, duration 120 min, with a yield value of 7.05%.

Chitin and its derivatives: Functional biopolymers for developing bioproducts for sustainable agriculture-A reality?

Chitinous materials (chitin and its derivatives) are obtained from renewable sources, mainly shellfish waste, having a great potential for the development of bioproducts as alternatives to synthetic agrochemicals. Recent studies have provided evidence that the use of these biopolymers can help control postharvest diseases, increase the content of nutrients available to plants, and elicit positive metabolic changes that lead to higher plant resistance against pathogens. However, agrochemicals are still widely and intensively used in agriculture. This perspective addresses the gap in knowledge and innovation to make bioproducts based on chitinous materials more competitive in the market. It also provides the readers with background to understand why these products are scarcely used and the aspects that need to be considered to increase their use. Finally, information on the development and commercialization of agricultural bioproducts containing chitin or its derivatives in the Chilean market is also provided.

Paenibacillus agilis sp. nov., Paenibacillus cremeus sp. nov. and Paenibacillus terricola sp. nov., isolated from rhizosphere soils

Members of the genus Paenibacillus are well known for their metabolic versatility and great application potential in plant growth promotion. Three novel bacterial strains, designated N4^T, JC52^T and PR3^T, were isolated from rhizosphere soils and characterized by using a polyphasic taxonomic approach. The 16S rRNA gene sequence phylogenetic and phylogenomic analysis revealed that the three strains belonged to the genus Paenibacillus and formed three independent branches distinct from all reference strains. The results of DNA-DNA hybridization (DDH) and average nucleotide identity (ANI) analyses between the three strains and their relatives further demonstrated that the three strains represented different novel genospecies. Strain N4^T exhibited the highest similarity, ANI and digital DDH values with Paenibacillus assamensis DSM 18201^T (99.0/87.5/33.9 %) and Paenibacillus insulae DS80^T (97.2/-/18.2±1.2 %). Values for JC52^T with Paenibacillus validus NBRC 15382^T were 96.9, 73.3 and 19.6 %, and with Paenibacillus rigui JCM 16352^T were 96.1, 72.1 and 19.3 %. Values for PR3^T with Paenibacillus ginsengiterrae DCY89^T were 98.2, - and 31.8±1.5 %, with Paenibacillus cellulosilyticus ASM318225v1^T were 97.8, 83.3 and 26.7 %, and with Paenibacillus kobensis NBRC 15729^T were 97.6, 75.7 and 20.4 %. Cells of the three novel bacterial strains were Gram-positive, spore-forming, motile and rod-shaped. The novel species contained anteiso-C_15 : 0 and MK-7 as the predominant fatty acid and menaquinone, respectively. The novel strains have numerous similar known clusters of non-ribosomal peptide synthetases, siderophores, lanthipeptide, lassopeptide-like bacillibactin, paeninodin and polyketide-like chejuenolide A/B lankacidin C. Based on the distinct morphological, physiological, chemotaxonomic and phylogenetic differences from their closest phylogenetic neighbours, we propose that strains N4^T, JC52^T and PR3^T represent novel species of the genus Paenibacillus, with the names Paenibacillus agilis sp. nov. (=KACC 19717^T=JCM 32775^T), Paenibacillus cremeus sp. nov. (=KACC 21221^T=NBRC 113867^T) and Paenibacillus terricola sp. nov. (=KACC 21455^T=NBRC 114385^T), respectively.

Biotechnologically produced chitosans with nonrandom acetylation patterns differ from conventional chitosans in properties and activities

Chitosans are versatile biopolymers with multiple biological activities and potential applications. They are linear copolymers of glucosamine and N-acetylglucosamine defined by their degree of polymerisation (DP), fraction of acetylation (F_A), and pattern of acetylation (PA). Technical chitosans produced chemically from chitin possess defined DP and F_A but random PA, while enzymatically produced natural chitosans probably have non-random PA. This natural process has not been replicated using biotechnology because chitin de-N-acetylases do not efficiently deacetylate crystalline chitin. Here, we show that such enzymes can partially N-acetylate fully deacetylated chitosan in the presence of excess acetate, yielding chitosans with F_A up to 0.7 and an enzyme-dependent non-random PA. The biotech chitosans differ from technical chitosans both in terms of physicochemical and nanoscale solution properties and biological activities. As with synthetic block co-polymers, controlling the distribution of building blocks within the biopolymer chain will open a new dimension of chitosan research and exploitation.

Chitosan degradation products promote healing of burn wounds of rat skin

Burns can impair the barrier function of the skin, and small burns can also cause high mortality. The WHO has described that over 180,000 people die of burns worldwide each year. Thus, the treatment of burn wounds is a major clinical challenge. Chitooligosaccharides (COS) are alkaline amino oligosaccharides with small molecular weights obtained by enzyme or chemical degradation of chitosan. With the characteristics of biocompatibility, water solubility and degradability, it has attracted increasing attention in the fields of biomedicine. In the present study, we used COS to treat deep second-degree burn wounds of rat skin and found that COS was able to promote wound healing. We also revealed that COS could promote fibroblast proliferation. Transcriptome sequencing analysis was performed on COS-treated fibroblasts to identify the underlying mechanisms. The results showed that COS was able to promote wound healing through regulation of the mitogen-activated protein kinase (MAPK) pathway and growth factor Hepatocyte Growth Factor (HGF). Our results provide a potential drug for burn wound therapy and the related molecular mechanism.

Bio-Inspired Rhamnolipids, Cyclic Lipopeptides and a Chito-Oligosaccharide Confer Protection against Wheat Powdery Mildew and Inhibit Conidia Germination

Plant protection is mainly based on the application of synthetic pesticides to limit yield losses resulting from diseases. However, the use of more eco-friendly strategies for sustainable plant protection has become a necessity that could contribute to controlling pathogens through a direct antimicrobial effect and/or an induction of plant resistance. Three different families of natural or bioinspired compounds originated from bacterial or fungal strains have been evaluated to protect wheat against powdery mildew, caused by the biotrophic Blumeria graminis f.sp. tritici (Bgt). Thus, three bio-inspired mono-rhamnolipids (smRLs), three cyclic lipopeptides (CLPs, mycosubtilin (M), fengycin (F), surfactin (S)) applied individually and in mixtures (M + F and M + F + S), as well as a chitosan oligosaccharide (COS) BioA187 were tested against Bgt, in planta and in vitro. Only the three smRLs (Rh-Eth-C12, Rh-Est-C12 and Rh-Succ-C12), the two CLP mixtures and the BioA187 led to a partial protection of wheat against Bgt. The higher inhibitor effects on the germination of Bgt spores in vitro were observed from smRLs Rh-Eth-C12 and Rh-Succ-C12, mycosubtilin and the two CLP mixtures. Taking together, these results revealed that such molecules could constitute promising tools for a more eco-friendly agriculture.

Effect of chitooligosaccharides with a specific degree of polymerization on multiple targets in T2DM mice

Chitooligosaccharides (COS) are found naturally in the ocean and present a variety of physiological activities, of which hypoglycemic action has attracted considerable research attention. This study aimed to assess the therapeutic effect of COS on mice suffering from type 2 diabetes mellitus (T2DM). COS effectively reduced blood glucose and blood lipid levels and improved glucose tolerance. Furthermore, COS revealed strong inhibitory activity against α-glucosidase, reducing postprandial blood glucose levels. Molecular docking data showed that COS might interact with surrounding amino acids to form a complex and decrease α-glucosidase activity. Additionally, COS enhanced insulin signal transduction and glycogen synthesis while restricting gluconeogenesis in the liver and muscles, reducing insulin resistance (IR) as a result. Moreover, COS effectively protected and restored islet cell function to increase insulin secretion. These results indicated that COS exhibited a significant hypoglycemic effect with multi-target participation. Therefore, COS may serve as a new preventive or therapeutic drug for diabetes to alleviate metabolic syndrome.

Potential Medical Applications of Chitooligosaccharides

Chitooligosaccharides, also known as chitosan oligomers or chitooligomers, are made up of chitosan with a degree of polymerization (DP) that is less than 20 and an average molecular weight (MW) that is lower than 3.9 kDa. COS can be produced through enzymatic conversions using chitinases, physical and chemical applications, or a combination of these strategies. COS is of significant interest for pharmacological and medical applications due to its increased water solubility and non-toxicity, with a wide range of bioactivities, including antibacterial, anti-inflammatory, anti-obesity, neuroprotective, anticancer, and antioxidant effects. This review aims to outline the recent advances and potential applications of COS in various diseases and conditions based on the available literature, mainly from preclinical research. The prospects of further in vivo studies and translational research on COS in the medical field are highlighted.

Bioeconomic production of high-quality chitobiose from chitin food wastes using an in-house chitinase from Vibrio campbellii

Marine Vibrio species are natural degraders of chitin and usually secrete high levels of chitinolytic enzymes to digest recalcitrant chitin to chitooligosaccharides. This study used an endochitinase (VhChiA) from Vibrio campbellii to produce high-quality chitobiose from crustacean chitins. The enzyme was shown to be fully active and stable over 24 h when BSA was used as an additive. When different chitin sources were tested, VhChiA preferentially digested shrimp and squid (α) chitins compared to crab (β) chitin and did not utilize non-chitin substrates. The overall yields of chitobiose obtained from small-scale production using a single-step reaction was 96% from shrimp, and 91% from squid pen and crab-shell chitins. Larger-scale production yielded 200 mg of chitobiose, with > 99% purity after a desalting and purification step using preparative HPLC. In conclusion, we report the employment of an in-house produced chitinase as an effective biocatalyst to rapidly convert chitin food wastes to chitobiose, in a quantity and quality suitable for use in research and commercial purposes. Chitobiose production by this economical and eco-friendly approach can be easily scaled up to obtain multi-gram quantities of chitobiose for chemo-enzymic synthesis of rare chitooligosaccharide derivatives and long chain chitooligosaccharides, as well as preparation of sugar-based functionalized nanomaterials.