Seafood waste: a source for preparation of commercially employable chitin/chitosan materials

Investigation on dung beetle's (Heliocopris Hope, 1838) chitosan valorisation for hydrogel 3D printing

Biopolymers and their derivatives are materials with increasing interest for industry and especially for sustainable engineering development. Among such kind of materials, carbohydrate polymer like highly deacetylated chitin (chitosan) is widely used for a wide range of applications, including material and biomedical developments. The majority of industrially produced chitosan is based on chitin extracted from crustacean exoskeleton. However, with increase of interest on this material, chitosan's production will rapidly become insufficient and other species should be investigated as new sources of chitosan. In the present work, we focus on the preparation of chitosan from giant dung beetles (Genus Heliocopris, Hope, 1838). This genus was chosen to show the possibility to take animals that develop and leave near dejection and valuate them for material applications. This work includes all the chitosan extraction procedures, chitosan characterisation IR, SEM, NMR, ash content, and deacetylation degree. Finally, the prepared carbohydrate polymer is used to form hydrogel. The prepared gel has been characterised and used for 3D printing, to show the compatibility of extracted chitosan with biomaterial application.

An improved extraction and purification method for obtaining high-quality chitin and chitosan from blue swimmer (Portunus pelagicus) crab shell waste

Portunus pelagicus shell waste is highly accumulated in seafood processing factories and has low commercial applications. The objective of this study was to modify and develop a scale-up, simple, and high-yielding chemical method for extraction and purification of chitin and chitosan from P. pelagicus shell waste. The developed method included a new "pretreatment" process using acetic acid followed by chemical treatments at each purification step. The final product was characterized by XRD and FTIR spectroscopy. Control chitin and chitosan were produced using a pre-described method for comparison. Yields of crude chitin, chitosan, and purified chitosan were 32.52 ± 0.68%, 26.28 ± 0.47%, and 21.78 ± 0.34% respectively whereas in the control chitin and chitosan the yields were 20.34 ± 0.72% and 13.79 ± 0.93% respectively (p < 0.05). Better physicochemical and functional properties were recorded in the developed method (p < 0.05). Hence the developed methodology can be scaled up and used in industrial applications.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-021-01002-x.

Impact of Chitosan on Water Stability and Wettability of Soils

Chitosan has become increasingly applied in agriculture worldwide, thus entering the soil environment. We hypothesized that chitosan should affect the water stability of soil. Since this problem has not been studied to date, we examined, for the first time, the influence of chitosan on the water stability and wettability of soil aggregates. The aggregates were prepared from four soils with various properties amended with different amounts of two kinds of powdered chitosan, and subjected to 1 and/or 10 wetting–drying cycles. The water stability was measured by monitoring air bubbling after aggregate immersion in water, and the wettability was measured by a water drop penetration test. The biopolymer with a lower molecular mass, lower viscosity, and higher degree of deacetylation was more effective in increasing the water stability of the soil than the biopolymer with a higher molecular mass, higher viscosity, and lower deacetylation degree. After a single wetting-drying cycle, the water stability of the soil aggregates containing chitosan with a higher molecular mass was generally lower than that of the soil; after ten wetting–drying cycles, the water stability increased 1.5 to 20 times depending on the soil. The addition of low-molecular-mass chitosan after a single wetting-drying cycle caused the water stability to become one to two hundred times higher than that of the soil. A trial to find out which soil properties (pH, C and N content, bulk density, porosity, and particle size distribution) are responsible for the effectiveness of chitosan action was not successful, and this will be the objective of further studies.

Development of nanobiomaterial for wound healing based on silver nanoparticles loaded on chitosan hydrogel

The objective of this study was to develop nanobiomaterial containing silver nanoparticles (AgNPs) for wound healing. AgNPs were synthesized using Saussurea lappa (Sl) aqueous root extract as reducing agent and were characterized physico-chemically using UV-vis spectral studies, XRD, FESEM, TEM, FTIR spectral analysis, DLS, and TG-DSC. Sl AgNPs production was optimized using response surface methodology. The cytotoxicity of Sl AgNPs was assessed by THP1 cell lines, which showed that Sl AgNPs were nontoxic with an IC50 of 151.10 μg/mL at 24 h. For topical application, Sl AgNPs was loaded on chitosan hydrogel was characterized through spreadability, in vitro release, antibacterial activity, swelling behavior, and SEM analysis. The chitosan Sl AgNPs hydrogel was subjected acute dermal toxicity test using Wistar albino rats and was found to be nontoxic. The excisional wound model was created along with Pseudomonas aeruginosa as an inoculant in Wistar albino rats. The chitosan Sl AgNPs hydrogel treated rats showed excellent wound healing qualities, lower bacterial counts, and enhanced production of connective tissues. Our findings strongly suggest that AgNPs synthesized from Saussurea lappa root extract loaded on chitosan hydrogel possibly applied for the remedy of infectious wounds at a concentration of 0.1 mg of Sl AgNPs/g of hydrogel.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-03030-0.

Cloning, expression, purification and characterization of chitin deacetylase extremozyme from halophilic Bacillus aryabhattai B8W22

Chitin deacetylase (CDA) (EC 3.5.1.41) is a hydrolytic enzyme that belongs to carbohydrate esterase family 4 as per the CAZY database. The CDA enzyme deacetylates chitin into chitosan. As the marine ecosystem is a rich source of chitin, it would also hold the unexplored extremophiles. In this study, an organism was isolated from 40 m sea sediment under halophilic condition and identified as Bacillus aryabhattai B8W22 by 16S rRNA sequencing. The CDA gene from the isolate was cloned and overexpressed in E. coli Rosetta pLysS and purified using a Ni-NTA affinity chromatography. The enzyme was found active on both ethylene glycol chitin (EGC) and chitooligosaccharides (COS). The enzyme characterization study revealed, maximum enzyme velocity at one hour, optimum pH at 7 with 50 mM Tris-HCl buffer, optimum reaction temperature of 30 ºC in standard assay conditions. The co-factor screening affirmed enhancement in the enzyme activity by 142.43 ± 7.13% and 146.88 ± 4.09% with substrate EGC and COS, respectively, in the presence of 2 mM Mg2+. This activity was decreased with the inclusion of EDTA and acetate in the assay solutions. The enzyme was found to be halotolerant; the relative activity increased to 116.98 ± 3.87% and 118.70 ± 0.98% with EGC and COS as substrates in the presence of 1 M NaCl. The enzyme also demonstrated thermo-stability, retaining 87.27 ± 2.85% and 94.08 ± 0.92% activity with substrate EGC and COS, respectively, upon treatment at 50 ºC for 24 h. The kinetic parameters K m, V max, and K cat were 3.06E-05 µg mL-1, 3.06E + 01 µM mg-1 min-1 and 3.27E + 04 s-1, respectively, with EGC as the substrate and 7.14E-07 µg mL-1, 7.14E + 01 µM mg-1 min-1 and 1.40E + 06 s-1, respectively, with COS as the substrate. The enzyme was found to be following Michaelis-Menten kinetics with both the polymeric and oligomeric substrates. In recent years, enzymatic conversion of chitosan is gaining importance due to its known pattern of deacetylation and reproducibility. Thus, this BaCDA extremozyme could be used for industrial production of chitosan polymer as well as chitosan oligosaccharides for biomedical application.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-03073-3.

Recent insights into carrageenan-based bio-nanocomposite polymers in food applications: A review

Nanotechnology has proven as progressive technology that enables to contribute, develop several effective and sustainable changes in food products. Incorporating nanomaterials like TiO₂, SiO₂, Halloysite nano clay, Copper sulfide, Bentonite nano clay, in carrageenan to develop innovative packaging materials with augmented mechanical and antimicrobial properties along with moisture and gas barrier properties that can produce safe and healthy foods. Intervention of carrageenan-based bio-nanocomposites as food packaging constituents has shown promising results in increasing the shelf stability and food quality by arresting the microbial growth. Nanomaterials can be incorporated within the carrageenan for developing active packaging systems for continuous protection of food products under different storage environments from farm to the fork to ensure quality and safety of foods. Carrageenan based bio nanocomposite packaging materials can be helpful to reduce the environmental concerns due to their high biodegradability index. This review gives insight about the current trends in the applications of carrageenan-based bio nanocomposites for different food packaging applications.

Chitosan Functionalization: Covalent and Non-Covalent Interactions and Their Characterization

Chitosan (CS) is a natural biopolymer that has gained great interest in many research fields due to its promising biocompatibility, biodegradability, and favorable mechanical properties. The versatility of this low-cost polymer allows for a variety of chemical modifications via covalent conjugation and non-covalent interactions, which are designed to further improve the properties of interest. This review aims at presenting the broad range of functionalization strategies reported over the last five years to reflect the state-of-the art of CS derivatization. We start by describing covalent modifications performed on the CS backbone, followed by non-covalent CS modifications involving small molecules, proteins, and metal adjuvants. An overview of CS-based systems involving both covalent and electrostatic modification patterns is then presented. Finally, a special focus will be given on the characterization techniques commonly used to qualify the composition and physical properties of CS derivatives.

Heterologous Expression of a Thermostable Chitinase from Myxococcus xanthus and Its Application for High Yield Production of Glucosamine from Shrimp Shell

Glucosamine (GlcN) is a widely used food supplement. Hence, enormous attention has been concerned with enzymatic production of GlcN owing to its advantage over a chemical approach. In this study, a previously unstudied chitinase gene (MxChi) in the genome of Myxococcus xanthus was cloned, expressed in recombinant soluble form and purified to homogeneity. TLC-, UPLC-, and microplate-reader- based activity tests confirmed MxChi hydrolyzes colloidal chitin to chitobiose as sole product. The optimal catalytic pH and temperature of MxChi was identified as 7.0 and 55 °C, respectively. MxChi exhibited 80% activity after 72 h incubation at 37 °C. The site-directed mutagenesis revealed that the amino acids D323A, D325A, and E327A of MxChi were in the DXDXE catalytic motif of GH18. When coupled with β-N-acetylhexosaminidase (SnHex) and deacetylase (CmCBDA), the enzyme allowed one-pot extraction of GlcN from colloidal chitin and shrimp shell. The optimal condition was 37 °C, pH 8.0, and 1/3/16.5 (MxChi/SnHex/CmCBDA), conducted by orthogonal design for the enzymatic cascades. Under this condition, the yield of GlcN was 26.33 mg from 400 mg shrimp shell. Facile recombinant in E. coli, robust thermostability and pure product herein makes newly discovered chitinase a valuable candidate for the green recycling of chitin rich waste.

TEMPO-oxidized nanochitin based hydrogels and inter-structure tunable cryogels prepared by sequential chemical and physical crosslinking

Well dispersibility of 2,2,6,6-tetramethyl-piperidine-1-oxyl (TEMPO)-oxidized nanochitins under alkaline conditions supports the effective chemical crosslinking between nanochitin and epichlorohydrin. The storage modulus of nanochitin hydrogels can be promoted by approximately 10 times as the nanochitin-to-epichlorohydrin mass ratio changes from 4:1 (120 Pa) to 1:4 (1200 Pa). Besides the enhanced mechanical property of hydrogels, the inter-structure of resulting cryogels is found controllable. With increasing epichlorohydrin dosage, the inter-structure of cryogels transforms from a typical fiber-like to honeycomb-like texture. The balance between chemical crosslinking effect and electrostatic repulsion between nanochitins is believed to result this controllable inter-structure. Further immersing into acetic acid solution can greatly enhance the mechanical strength of nanochitin hydrogels due to the introduction of physical crosslinking domains by shielding the electrostatic repulsion, the storage modulus becomes two times higher after immersing in 50% (w/w) acetic acid solution, while the surface area of nanochitin cryogels decreases due to the denser structure.

Low-Phytotoxic Deep Eutectic Systems as Alternative Extraction Media for the Recovery of Chitin from Brown Crab Shells

The versatility of chitin and its derivatives has allowed their utilization in a wide range of applications, from wastewater treatment to pharmaceutical or biomedical industries. However, even though the extraction method used industrially is extremely efficient, it involves the use of strong acids and bases and results in the disposal of large quantities of toxic effluents. Deep eutectic systems (DESs) have emerged as a promising new class of alternative solvents, including for chitin recovery. Yet, the assessment of their toxicity has often been neglected. Therefore, in this work, the phytotoxicity of choline chloride (ChCl)/organic acid-based DESs toward wheat seeds was evaluated by measuring different growth parameters and stress biomarkers. DESs were then explored for the efficient recovery of chitin contained in brown crab shell residues at varying conditions of temperature and processing time as well as with and without water addition. The obtained chitin was then characterized through different analytical techniques and compared to a standard as well as to chitin obtained by a conventional acid/alkaline hydrolysis. Results have shown that by applying a ChCl/lactic acid-based DES (which was the system that showed the least phytotoxic effects on wheat; EC50 ≥ 1.6 mg/mL) at 130 °C, it was possible to obtain pure chitin (up to 98%) with characteristics similar to those presented by commercial chitin or chitin recovered by conventional hydrolysis in a shorter time (more than 8-fold faster), thus suggesting that ChCl/organic acid-based DESs can truly represent a low-phytotoxic alternative extraction media for the recovery of chitin from the crab shell biomass.

Microbial decomposition of crustacean shell for production of bioactive metabolites and study of its fertilizing potential

Crustacean shell waste disposal is considered as biggest problem in seafood processing centers. Incineration and landfilling are the commonest ways of disposal of the waste which causes environmental pollution. Microbial bio-conversion is one of the promising approaches to minimize the wastes by utilizing the same for deriving different value added metabolites. In this perspective, chitinase- and protease-producing bacterial strains were isolated from shrimp culture pond, and the potent isolate was subsequently identified as Alcaligenes faecalis SK10. Fermentative optimization of the production of chitinase (85.42 U/ml), protease (58.57 U/ml), and their catalytic products, viz., N-acetylamino sugar (84 μg/ml) and free amino acids (112 μg/ml), were carried out by utilizing shrimp and crab shell powder as principal substrate. The fermented hydrolysate (FH) was subsequently applied to evaluate its potential to be a candidate fertilizer for the growth of leguminous plant Pisum sativum and Cicer arietinum, and the results were compared with chitin, chitosan, and commercial biofertilizer amended group. The results revealed that FH have paramount potential to improve plants morpho-physiological parameters like stem and root length, chlorophyll, cellular RNA, protein content, and soil physico-chemical parameters like total nitrogen, magnesium, calcium, phosphorus, and potassium significantly (p < 0.05). Moreover, the application of FH also selectively encouraged the growth of free-living nitrogen-fixing bacteria, Rhizobium, phosphate-solubilizing bacteria in the soil by 4.82- and 5.27-, 5.57- and 4.71, and 7.64- and 6.92-fold, respectively, in the rhizosphere of P. sativum and C. arietinum, which collectively is a good sign for an ideal biofertilizer. Co-supplementation of FH with commercial PGPR-biofertilizer significantly influenced the morpho-physiological attributes of plant and physico-chemical and microbial attributes of soil. The study validated proficient and sustainable utilization of fermented hydrolysate of waste crustacean shell as biofertilizer.

Recent advances in the microbial synthesis of lactate-based copolymer

Due to the increasing environmental pollution of un-degradable plastics and the consumption of non-renewable resources, more attention has been attracted by new bio-degradable/based polymers produced from renewable resources. Polylactic acid (PLA) is one of the most representative bio-based materials, with obvious advantages and disadvantages, and has a wide range of applications in industry, medicine, and research. By copolymerizing to make up for its deficiencies, the obtained copolymers have more excellent properties. The development of a one-step microbial metabolism production process of the lactate (LA)-based copolymers overcomes the inherent shortcomings in the traditional chemical synthesis process. The most common lactate-based copolymer is poly(lactate-co-3-hydroxybutyrate) [P(LA-co-3HB)], within which the difference of LA monomer fraction will cause the change in the material properties. It is necessary to regulate LA monomer fraction by appropriate methods. Based on synthetic biology and systems metabolic engineering, this review mainly focus on how did the different production strategies (such as enzyme engineering, fermentation engineering, etc.) of P(LA-co-3HB) optimize the chassis cells to efficiently produce it. In addition, the metabolic engineering strategies of some other lactate-based copolymers are also introduced in this article. These studies would facilitate to expand the application fields of the corresponding materials.

The Food-Materials Nexus: Next Generation Bioplastics and Advanced Materials from Agri-Food Residues

The most recent strategies available for upcycling agri-food losses and waste (FLW) into functional bioplastics and advanced materials are reviewed and the valorization of food residuals are put in perspective, adding to the water-food-energy nexus. Low value or underutilized biomass, biocolloids, water-soluble biopolymers, polymerizable monomers, and nutrients are introduced as feasible building blocks for biotechnological conversion into bioplastics. The latter are demonstrated for their incorporation in multifunctional packaging, biomedical devices, sensors, actuators, and energy conversion and storage devices, contributing to the valorization efforts within the future circular bioeconomy. Strategies are introduced to effectively synthesize, deconstruct and reassemble or engineer FLW-derived monomeric, polymeric, and colloidal building blocks. Multifunctional bioplastics are introduced considering the structural, chemical, physical as well as the accessibility of FLW precursors. Processing techniques are analyzed within the fields of polymer chemistry and physics. The prospects of FLW streams and biomass surplus, considering their availability, interactions with water and thermal stability, are critically discussed in a near-future scenario that is expected to lead to next-generation bioplastics and advanced materials.

Chitin derivatives of NAG and chitosan nanoparticles from marine disposal yards and their use for economically feasible fish feed development

Globally, the disposal of shellfishery waste is a major challenge and causes a risk to the coastal region. For potential development in aquaculture, the use of safe supplements to improve fish production and health is important. Chitosan (CS) used as feed additives for several fish species that enhanced production and immunity. The present study was intended to assess the effect of feed additives N-acetyl-d-glucosamine (NAG) loaded chitosan nanoparticles (CSNPs) on productivity, survival rate, and protein conversion efficiency of Oreochromis niloticus (L.). This is the first report on the effect of CSNPs and NAG loaded CSNPs as feed additives enhanced growth performance and non-specific immunity of O. niloticus. CSNPs and NAG loaded CSNPs were synthesized and characterized by scanning and transmission electron microscope, FT-IR, X-ray diffraction, particle size distribution, and zeta sizer. Fish (15.30 ± 0.23 g) administered diets fortified with 0.0, 0.25, 0.5, 1.0, and 2.0 g CSNPs/kg feed loaded with NAG for 45 d. The diets containing 1.0 g/kg NAG loaded CSNPs enhanced specific growth rate, weight gain, survival rate, respiratory burst, and lysozyme activities of tilapia compared control group. The data shows biologically active CSNPs and NAG loaded CSNPs are potent antimicrobial agents against selected bacterial pathogens. In conclusion, the findings suggested that the dietary supplement containing NAG loaded CSNPs significantly increased immune-modulatory properties, growth performance, and enhanced their disease resistance of Nile tilapia.

Understanding the structural diversity of chitins as a versatile biomaterial

Chitin is one of the most abundant biopolymers, and it has adopted many different structural conformations using a combination of different natural processes like biopolymerization, crystallization and non-equilibrium self-assembly. This leads to a number of striking physical effects like complex light scattering and polarization as well as unique mechanical properties. In doing so, chitin uses a fine balance between the highly ordered chain conformations in the nanofibrils and random disordered structures. In this opinion piece, we discuss the structural hierarchy of chitin, its crystalline states and the natural biosynthesis processes to create such specific structures and diversity. Among the examples we explored, the unified question arises from the generation of completely different bioarchitectures like the Christmas tree-like nanostructures, gyroids or helicoidal geometries using similar dynamic non-equilibrium growth processes. Understanding the in vivo development of such structures from gene expressions, enzymatic activities as well as the chemical matrix employed in different stages of the biosynthesis will allow us to shift the material design paradigms. Certainly, the complexity of the biology requires a collaborative and multi-disciplinary research effort. For the future's advanced technologies, using chitin will ultimately drive many innovations and alternatives using biomimicry in materials science. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 1)'.

Production of Thermophilic Chitinase by Paenibacillus sp. TKU052 by Bioprocessing of Chitinous Fishery Wastes and Its Application in N-acetyl-D-glucosamine Production

The bioprocessing of chitinous fishery wastes (CFWs) to chitinases through fermentation approaches has gained importance owing to its great benefits in reducing the enzyme production cost, and utilizing chitin waste. In this work, our study of the chitinase production of Paenibacillus sp. TKU052 in the presence of different kinds of CFWs revealed a preference for demineralized crab shells powder (deCSP); furthermore, a 72 kDa chitinase was isolated from the 0.5% deCSP-containing medium. The Paenibacillus sp. TKU052 chitinase displayed maximum activity at 70 °C and pH 4-5, while Zn2+, Fe3+, Triton X-100, Tween 40, and SDS exerted a negative effect on its activity, whereas Mn2+ and 2-mercaptoethanol were found to potentially enhance the activity. Among various kinds of polysaccharide, Paenibacillus sp. TKU052 chitinase exhibited the best catalytic activity on colloidal chitin (CC) with Km = 9.75 mg/mL and Vmax = 2.43 μmol/min. The assessment of the hydrolysis of CC and N-acetyl chitooligosaccharides revealed that Paenibacillus sp. TKU052 chitinase possesses multiple catalytic functions, including exochitinase, endochitinase, and N-acetyl-β-D-glucosaminidase activities. Finally, the combination of Paenibacillus sp. TKU052 chitinase and Streptomyces speibonae TKU048 N-acetyl-β-D-glucosaminidase could efficiently convert CC to N-acetyl-D-glucosamine (GlcNAc) with a production yield of 94.35-98.60% in 12-24 h.

Extraction of chitin from edible crab shells of Callinectes sapidus and comparison with market purchased chitin

Chitin and its derived products have immense economic value due to their vital role in various biological activities as well as biomedical and industrial application. Insects, microorganism and crustaceans are the main supply of chitin but the crustaceans shell like shrimp, krill, lobsters and crabs are the main commercial sources. Chitin content of an individual varies depending on the structures possessing the polymer and the species. In this study edible crabs' shells (Callinectes sapidus) were demineralized and deproteinized resulting in 13.8% (dry weight) chitin recovery from chitin wastes. FTIR and XRD analyses of the experimental crude as well as purified chitins revealed that both were much comparable to the commercially purchased controls. The acid pretreatment ceded 54g of colloidal chitin that resulted in 1080% of the crude chitin. The colloidal chitin was exploited for isolation of eighty five chitinolytic bacterial isolates from different sources. Zone of clearance was displayed by the thirty five isolates (41.17%) succeeding their growth at pH 7 on colloidal chitin agar medium. Maximum chitinolytic activity i.e. 301.55 U/ml was exhibited by isolate JF70 when cultivated in extracted chitin containing both carbon and nitrogen. The study showed wastes of blue crabs can be utilized for extraction of chitin and isolation of chitinolytic bacteria that can be used to degrade chitin waste, resolve environmental pollution as well as industrial purpose.

Modifications of polysaccharide-based biomaterials under structure-property relationship for biomedical applications

Polysaccharides are well accepted biomaterials that have attracted considerable attention. Compared with other materials under research, polysaccharides show unique advantages: they are available in nature and are normally easily acquired, those acquired from nature show favorable immunogenicity, and are biodegradable and bioavailable. The bioactivity and possible applications are based on their chemical structure; however, naturally acquired polysaccharides sometimes have unwanted flaws that limit further applications. For this reason, carefully summarizing the possible modifications of polysaccharides to improve them is crucial. Structural modifications can not only provide polysaccharides with additional functional groups but also change their physicochemical properties. This review based on the structure-property relation summarizes the common chemical modifications of polysaccharides, the related bioactivity changes, possible functionalization methods, and major possible biomedical applications based on modified polysaccharides.

Enzymatic approaches in the bioprocessing of shellfish wastes

Several tonnes of shellfish wastes are generated globally due to the mass consumption of shellfish meat from crustaceans like prawn, shrimp, lobster, crab, Antarctic krill, etc. These shellfish wastes are a reservoir of valuable by-products like chitin, protein, calcium carbonate, and pigments. In the present scenario, these wastes are treated chemically to recover chitin by the chitin and chitosan industries, using hazardous chemicals like HCl and NaOH. Although this process is efficient in removing proteins and minerals, the unscientific dumping of harmful effluents is hazardous to the ecosystem. Stringent environmental laws and regulations on waste disposal have encouraged researchers to look for alternate strategies to produce near-zero wastes on shellfish degradation. The role of enzymes in degrading shellfish wastes is advantageous yet has not been explored much, although it produces bioactive rich protein hydrolysates with good quality chitin. The main objective of the review is to discuss the potential of various enzymes involved in shellfish degradation and their opportunities and challenges over chemical processes in chitin recovery.

Genome and Secretome Analysis of Staphylotrichum longicolleum DSM105789 Cultured on Agro-Residual and Chitinous Biomass

Staphylotrichum longicolleum FW57 (DSM105789) is a prolific chitinolytic fungus isolated from wood, with a chitinase activity of 0.11 ± 0.01 U/mg. We selected this strain for genome sequencing and annotation, and compiled its growth characteristics on four different chitinous substrates as well as two agro-industrial waste products. We found that the enzymatic mixture secreted by FW57 was not only able to digest pre-treated sugarcane bagasse, but also untreated sugarcane bagasse and maize leaves. The efficiency was comparable to a commercial enzymatic cocktail, highlighting the potential of the S. longicolleum enzyme mixture as an alternative pretreatment method. To further characterize the enzymes, which efficiently digested polymers such as cellulose, hemicellulose, pectin, starch, and lignin, we performed in-depth mass spectrometry-based secretome analysis using tryptic peptides from in-gel and in-solution digestions. Depending on the growth conditions, we were able to detect from 442 to 1092 proteins, which were annotated to identify from 134 to 224 putative carbohydrate-active enzymes (CAZymes) in five different families: glycoside hydrolases, auxiliary activities, carbohydrate esterases, polysaccharide lyases, glycosyl transferases, and proteins containing a carbohydrate-binding module, as well as combinations thereof. The FW57 enzyme mixture could be used to replace commercial enzyme cocktails for the digestion of agro-residual substrates.

Recent Applications of Biopolymers Derived from Fish Industry Waste in Food Packaging

Fish waste is attracting growing interest as a new raw material for biopolymer production in different application fields, mainly in food packaging, with significant economic and environmental advantages. This review paper summarizes the recent advances in the valorization of fish waste for the preparation of biopolymers for food packaging applications. The issues related to fishery industry waste and fish by-catch and the potential for re-using these by-products in a circular economy approach have been presented in detail. Then, all the biopolymer typologies derived from fish waste with potential applications in food packaging, such as muscle proteins, collagen, gelatin, chitin/chitosan, have been described. For each of them, the recent applications in food packaging, in the last five years, have been overviewed with an emphasis on smart packaging applications. Despite the huge industrial potential of fish industry by-products, most of the reviewed applications are still at lab-scale. Therefore, the technological challenges for a reliable exploitation and recovery of several potentially valuable molecules and the strategies to improve the barrier, mechanical and thermal performance of each kind of biopolymer have been analyzed.

Microbial chitinases: properties, enhancement and potential applications

Chitinases are a category of hydrolytic enzymes that catalyze chitin and are formed by a wide variety of microorganisms. In nature, microbial chitinases are primarily responsible for chitin decomposition and play a vital role in the balance of carbon and nitrogen ratio in the ecosystem. The physicochemical attributes and the source of chitinase are the main bases that determine their functional characteristics and hydrolyzed products. Several chitinases have been reported and characterized, and they obtain a wider consideration for their utilization in a large number of uses such as in agriculture, food, environment, medicine and pharmaceutical companies. The antifungal and insecticidal impacts of several chitinases have been extensively studied, aiming to protect crops from phytopathogenic fungi and insects. Chitooligosaccharides synthesized by chitin degradation have been shown to improve human health through their antimicrobial, antioxidant, anti-inflammatory and antitumor properties. This review aims at investigating chitinase production, properties and their potential applications in various biotechnological fields.

Ag-Based Synergistic Antimicrobial Composites. A Critical Review

The emerging problem of the antibiotic resistance development and the consequences that the health, food and other sectors face stimulate researchers to find safe and effective alternative methods to fight antimicrobial resistance (AMR) and biofilm formation. One of the most promising and efficient groups of materials known for robust antimicrobial performance is noble metal nanoparticles. Notably, silver nanoparticles (AgNPs) have been already widely investigated and applied as antimicrobial agents. However, it has been proposed to create synergistic composites, because pathogens can find their way to develop resistance against metal nanophases; therefore, it could be important to strengthen and secure their antipathogen potency. These complex materials are comprised of individual components with intrinsic antimicrobial action against a wide range of pathogens. One part consists of inorganic AgNPs, and the other, of active organic molecules with pronounced germicidal effects: both phases complement each other, and the effect might just be the sum of the individual effects, or it can be reinforced by the simultaneous application. Many organic molecules have been proposed as potential candidates and successfully united with inorganic counterparts: polysaccharides, with chitosan being the most used component; phenols and organic acids; and peptides and other agents of animal and synthetic origin. In this review, we overview the available literature and critically discuss the findings, including the mechanisms of action, efficacy and application of the silver-based synergistic antimicrobial composites. Hence, we provide a structured summary of the current state of the research direction and give an opinion on perspectives on the development of hybrid Ag-based nanoantimicrobials (NAMs).

A review on the potential uses of deep eutectic solvents in chitin and chitosan related processes

Ionic liquids (ILs) as well as closely related deep eutectic solvents (DESs) have been the most promising discoveries in the "Green Chemistry" world in recent years as types of solvents. Deep eutectic solvents are received as potential alternatives to the conventional organic solvents with other advantages such as renewability, reusability, biodegradability, nontoxicity, large-scale availability, having very low vapour pressure, low flammability and easy in preparation. Chitin is the second most abundant biopolymers in the nature that can be extracted from many aquatic and terrestrial organisms also some of the microorganisms. Chitin and its derivatives have applications in many fields such as medical, food-beverages, agriculture and cosmetics. This review reports the major contributions of DESs in chitin and chitosan related studies and summarizes recent advances in some applications such as extraction media, bio-film fabrication, nanomaterial preparation, chitosan methylation, chitin dissolution, composite material preparation.

Valorization of Seafood Processing Discards: Bioconversion and Bio-Refinery Approaches

The seafood industry generates large volumes of waste. These include processing discards consisting of shell, head, bones intestine, fin, skin, voluminous amounts of wastewater discharged as effluents, and low-value under-utilized fish, which are caught as by-catch of commercial fishing operations. The discards, effluents, and by-catch are rich in nutrients including proteins, amino acids, lipids containing good proportions of polyunsaturated fatty acids (PUFA), carotenoids, and minerals. The seafood waste is, therefore, responsible for loss of nutrients and serious environmental hazards. It is important that the waste is subjected to secondary processing and valorization to address the problems. Although chemical processes are available for waste treatment, most of these processes have inherent weaknesses. Biological treatments, however, are environmentally friendly, safe, and cost-effective. Biological treatments are based on bioconversion processes, which help with the recovery of valuable ingredients from by-catch, processing discards, and effluents, without losing their inherent bioactivities. Major bioconversion processes make use of microbial fermentations or actions of exogenously added enzymes on the waste components. Recent developments in algal biotechnology offer novel processes for biotransformation of nutrients as single cell proteins, which can be used as feedstock for the recovery of valuable ingredients and also biofuel. Bioconversion options in conjunction with a bio-refinery approach have potential for eco-friendly and economical management of seafood waste that can support sustainable seafood production.

Chemically versus thermally processed brown shrimp shells or Chinese mitten crab as a source of chitin, nutrients or salts and as microbial stimulant in soilless strawberry cultivation

Brown shrimp (Crangon crangon) shells and Chinese mitten crab (Eriocheir sinensis) were chemically demineralized and deproteinized (denoted as M1 to M4 for the shrimp shells and M5 to M7 for the Chinese mitten crab), and shrimp shells were torrefied at 200 to 300 °C (denoted as R200, R255, R300), and were compared with a commercially available chitin source (denoted as reference chitin). Based on their chemical characteristics, a selection of chitin sources was tested for their N mineralization capacity. The N release was high for the chemically treated shrimp shells and Chinese mitten crab, but not for the torrefied shrimp shells with or without acid treatment, indicating that treatment at 200 °C or higher resulted in low N availability. Interaction with nutrients was tested in a leaching experiment with limed peat for three thermally and two chemically processed shrimp shells and the reference chitin source. The K concentrations in the leachate for the chemically treated shrimp shells and the reference chitin were lower than for limed peat during fertigation. Irreversible K retention was observed for one source of chemically treated shrimp shells, and the reference chitin. The thermally treated shrimp shells had a significantly higher net release of P, Na and Cl than the treatment without chitin source. Three shrimp shell based materials (M4, R200 and R300) and the reference chitin were tested in a greenhouse trial with strawberry at a dose of 2 g/L limed peat. A very positive and significant effect on Botrytis cinerea disease suppression in the leaves was found for the reference chitin, M4 and R200 compared to the unamended control. The disease suppression of the 3 chitin sources was linked with an increase of the microbial biomass in the limed peat with 24% to 28% due to chitin decomposition and a 9-44% higher N uptake in the plants.

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.

Sustainable Agriculture Systems in Vegetable Production Using Chitin and Chitosan as Plant Biostimulants

Chitin and chitosan are natural compounds that are biodegradable and nontoxic and have gained noticeable attention due to their effective contribution to increased yield and agro-environmental sustainability. Several effects have been reported for chitosan application in plants. Particularly, it can be used in plant defense systems against biological and environmental stress conditions and as a plant growth promoter—it can increase stomatal conductance and reduce transpiration or be applied as a coating material in seeds. Moreover, it can be effective in promoting chitinolytic microorganisms and prolonging storage life through post-harvest treatments, or benefit nutrient delivery to plants since it may prevent leaching and improve slow release of nutrients in fertilizers. Finally, it can remediate polluted soils through the removal of cationic and anionic heavy metals and the improvement of soil properties. On the other hand, chitin also has many beneficial effects such as plant growth promotion, improved plant nutrition and ability to modulate and improve plants’ resistance to abiotic and biotic stressors. The present review presents a literature overview regarding the effects of chitin, chitosan and derivatives on horticultural crops, highlighting their important role in modern sustainable crop production; the main limitations as well as the future prospects of applications of this particular biostimulant category are also presented.

Factor XIII Cross-Linked Adhesive Chitosan Hydrogels

Biomedical adhesives have been found to be an attractive alternative to suturing in several circumstances. However, to date most of the clinically approved formulations are based on synthetic and highly reactive toxic chemicals. In this work, we aimed to combine for the first time the bioactive properties of the cationic polysaccharide chitosan and its intrinsic electrostatic binding to negatively charged tissues with the biocompatible and clinically compliant enzymatic cross-linking scheme of fibrin glue. This synergistic activity led to the generation of a transglutaminase Factor XIII cross-linkable chitosan formulation with fast gelation kinetics, tunable mechanical properties, antibacterial activity, and strong adhesion to cartilage.

Oxidative stress and cyto-genotoxicity induced by poly-d-glucosamine in human blood cells in vitro

Poly-N-acetyl-d-glucosamine (CH; chitin) is the main component of the insect skeleton, fungal cell wall, and many crustaceans, including crab and shrimp. CH is the most abundant in nature after cellulose, and it has a complex and hardly soluble structure. Poly-d-glucosamine (CHO; chitosan) is a soluble derivative of CH produced by deacetylation used in many fields, including human health. This study carried out the cytotoxic, genotoxic, and oxidative effects of CHO on human whole blood (hWB) and lymphocytes (LYMs) in dose ranges 6.25-2000 μg/mL, in vitro. Total antioxidant capacity (TAC) and total oxidant status (TOS) analyzes were performed on plasma to appreciate oxidative stress. 3-(4,5-Dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays were applied to understand the cytotoxicity. Chromosomal aberration (CA) and micronucleus (MN) methods were practiced to evaluate genotoxicity. 6.25-150 μg/mL doses increased TAC and decreased TOS. A decreasing and increasing curve from 200 to 2000 μg/mL on TAC and TOS values were determined, respectively. 0-250 μg/mL doses did not provide any cytotoxic data. However, 500-2000 μg/mL doses showed increasing cytotoxicity and genotoxicity. The study results showed that CHO does not pose a toxic risk to human health at low doses but may pose a threat at high doses.

Preparation of chitosan from waste shrimp shells fermented with Paenibacillus jamilae BAT1

In this study, chitin extraction from shrimp shell powder (SSP) using locally isolated Paenibacillus jamilae BAT1 (GenBank: MN176658), the preparation of chitosan from the extracted chitin, and the characterization and biological activity (antimicrobial and antioxidant) of the prepared chitosan (PC) were investigated. It was determined that P. jamilae BAT1 did not have chitinase activity but showed high protease activity and protein removal potential. Optimum pH, shell concentration and incubation time for deproteinization were determined as 7.0, 60 g/L and 4 days, respectively. Addition of KH₂PO₄ or MgSO₄ did not affect chitin extraction and deproteinization yield. The maximum yields of deproteinization, demineralization and chitin extraction yields were 87.67, 41.95 and 24.5%, respectively. The viscosity-average molecular weight of PC was determined as 1.41 × 10⁵ g/mol. The deacetylation degree of PC (86%) was found to be higher that of commercial chitosan (CC) (78%). DPPH scavenging activity of PC (IC₅₀ 0.59 mg/mL) was higher than that of CC (IC₅₀ 3.72 mg/mL). PC was found to have higher antimicrobial activity against the bacteria E. coli and S. aureus and the yeast C. albicans when compared to CC. This is the first study on the use of the bacterium P. jamilae in biological chitin extraction.

Emerging marine derived nanohydroxyapatite and their composites for implant and biomedical applications

Implant materials must mimic natural human bones with biocompatibility, osteoconductivity and mechanical stability to successfully replace damaged or disease-affected bones. Synthetic hydroxyapatite was incorporated with bioglass to mimic natural bones for replacing conventional implant materials which has led to certain toxicity issues. Hence, hydroxyapatite (HAp) are recently gaining applicational importance as they are resembling the structure and function of natural bones. Further, nanosized HAp is under extensive research to utilize them as a potential replacement for traditional implants with several exclusive properties. However, chemical synthesis of nano-HAp exhibited toxicity towards normal and healthy cells. Recently, biogenic Hap synthesis from marine and animal sources are introduced as a next generation implant materials, due to their mineral ion and significant porous architecture mediated biocompatibility and bone bonding ability, compared to synthetic HAp. Thus, the purpose of the paper is to give a bird's eye view into the conventional approaches for fabricating nano-HAp, its limitations and the significance of using marine organisms and marine food wastes as a precursor for biogenic nano-Hap production. Moreover, in vivo and in vitro analyses of marine source derived nano-HAp and their potential biomedical applications were also discussed.

Chitosan modifications for adsorption of pollutants - A review

In recent times, research interest into the development of biodegradable, cost-effective and environmental friendly adsorbents with favourable properties for adsorption of pollutants is a challenge. Modification of chitosan via different physical and chemical methods have gained attention as a promising approach for removing organic (such as dyes and pharmaceuticals) and inorganic (such as metal/metal ions) pollutants from aqueous medium. In this regard, researchers have reported grafting and cross-linking approach among others as a potentially useful method for chitosan's modification for improved adsorption efficiency with respect to pollutant uptake. This article reviews the trend in chitosan modification, with regards to the summary of some recently published works on modification of chitosan and their adsorption application in pollutants (metal ion, dyes and pharmaceuticals) removal from aqueous medium. The review uniquely highlights some common cross-linkers and grafting procedures for chitosan modification, their influence on structure and adsorption capacity of modified-chitosan with respect to pollutants removal. Findings revealed that the performance of modified chitosan for adsorption of pollutants depends largely on the modification method adopted, materials used for the modification and adsorption experimental conditions. Cross-linking is commonly utilized for improving the chemical and mechanical stabilities of chitosan but usually decreases adsorption capacity of chitosan/modified-chitosan for adsorption of pollutants. However, literature survey revealed that adsorption capacity of cross-linked chitosan based materials have been enhanced in recently published works either by grafting, incorporation of solid adsorbents (e.g metals, clays and activated carbon) or combination of both prior to cross-linking.

Chemical and physical Chitosan modification for designing enzymatic industrial biocatalysts: How to choose the best strategy?

Chitosan is one of the most abundant natural polymer worldwide, and due to its inherent characteristics, its use in industrial processes has been extensively explored. Because it is biodegradable, biocompatible, non-toxic, hydrophilic, cheap, and has good physical-chemical stability, it is seen as an excellent alternative for the replacement of synthetic materials in the search for more sustainable production methodologies. Thus being, a possible biotechnological application of Chitosan is as a direct support for enzyme immobilization. However, its applicability is quite specific, and to overcome this issue, alternative pretreatments are required, such as chemical and physical modifications to its structure, enabling its use in a wider array of applications. This review aims to present the topic in detail, by exploring and discussing methods of employment of Chitosan in enzymatic immobilization processes with various enzymes, presenting its advantages and disadvantages, as well as listing possible chemical modifications and combinations with other compounds for formulating an ideal support for this purpose. First, we will present Chitosan emphasizing its characteristics that allow its use as enzyme support. Furthermore, we will discuss possible physicochemical modifications that can be made to Chitosan, mentioning the improvements obtained in each process. These discussions will enable a comprehensive comparison between, and an informed choice of, the best technologies concerning enzyme immobilization and the application conditions of the biocatalyst.

Development of Covalent Chitosan-Polyethylenimine Derivatives as Gene Delivery Vehicle: Synthesis, Characterization, and Evaluation

There is an increasing interest in cationic polymers as important constituents of non-viral gene delivery vectors. In the present study, we developed a versatile synthetic route for the production of covalent polymeric conjugates consisting of water-soluble depolymerized chitosan (dCS; M_W 6–9 kDa) and low molecular weight polyethylenimine (PEI; 2.5 kDa linear, 1.8 kDa branched). dCS-PEI derivatives were evaluated based on their physicochemical properties, including purity, covalent bonding, solubility in aqueous media, ability for DNA condensation, and colloidal stability of the resulting polyplexes. They were complexed with non-integrating DNA vectors coding for reporter genes by simple admixing and assessed in vitro using liver-derived HuH-7 cells for their transfection efficiency and cytotoxicity. Using a rational screening cascade, a lead compound was selected (dCS-Suc-LPEI-14) displaying the best balance of biocompatibility, cytotoxicity, and transfection efficiency. Scale-up and in vivo evaluation in wild-type mice allowed for a direct comparison with a commercially available non-viral delivery vector (in vivo-jetPEI). Hepatic expression of the reporter gene luciferase resulted in liver-specific bioluminescence, upon intrabiliary infusion of the chitosan-based polyplexes, which exceeded the signal of the in vivo jetPEI reference formulation by a factor of 10. We conclude that the novel chitosan-derivative dCS-Suc-LPEI-14 shows promise and potential as an efficient polymeric conjugate for non-viral in vivo gene therapy.

Chitosan and Derivatives: Bioactivities and Application in Foods

Chitosan is a biodegradable, biocompatible, and nontoxic aminopolysaccharide. This review summarizes and discusses the structural modifications, including substitution, grafting copolymerization, cross-linking, and hydrolysis, utilized to improve the physicochemical properties and enhance the bioactivity and functionality of chitosan and related materials. This manuscript also reviews the current progress and potential of chitosan and its derivatives in body-weight management and antihyperlipidemic, antihyperglycemic, antihypertensive, antimicrobial antioxidant, anti-inflammatory, and immunostimulatory activities as well as their ability to interact with gut microbiota. In addition, the potential of chitosan and its derivatives as functional ingredients in food systems, such as film and coating materials, and delivery systems is discussed. This manuscript aims to provide up-to-date information to stimulate future discussion and research to promote the value-added utilization of chitosan in improving the safety, quality, nutritional value and health benefits, and sustainability of our food system while reducing the environmental hazards.

Functional foods and bioactive ingredients harnessed from the ocean: current status and future perspectives

With an increase in life expectancy and decrease of quality-of-life couple with the high prevalence of diseases, diet is expected to play a key function in sustaining human health. Nutritionists, food technologists and medical experts are working in synergy to cater for the increasing demand of food with associated therapeutic benefits, commonly known as functional food, that may improve well-being and reduce the risk of diseases. Interestingly, the marine ecosystem, due to its abundant and phenomenal biodiversity of marine organisms, constitutes a vital source of a panoply of healthy foods supply for the thriving functional food industry. Marine organisms such as seaweeds, sea cucumbers, sponges, and mollusks amongst others are sources of thousands of biologically active metabolites with antioxidant, anti-parasitic, antiviral, anti-inflammatory and anticancer properties. Given the growing number of research and interest to probe into the therapeutic roles of marine products, this review was designed to provide a comprehensive summary of the therapeutic properties of marine organisms (macroalgae, sea cucumbers and fish among others) which are consumed worldwide, in addition to their potentials and as sources of functional ingredients for developing novel food and fostering wellness. The gap between research development and actual commercialization, and future prospects of marine-based products also summarized to some extent.

A High-Throughput Screening System Based on Fluorescence-Activated Cell Sorting for the Directed Evolution of Chitinase A

Chitinases catalyze the degradation of chitin, a polymer of N-acetylglucosamine found in crustacean shells, insect cuticles, and fungal cell walls. There is great interest in the development of improved chitinases to address the environmental burden of chitin waste from the food processing industry as well as the potential medical, agricultural, and industrial uses of partially deacetylated chitin (chitosan) and its products (chito-oligosaccharides). The depolymerization of chitin can be achieved using chemical and physical treatments, but an enzymatic process would be more environmentally friendly and more sustainable. However, chitinases are slow-acting enzymes, limiting their biotechnological exploitation, although this can be overcome by molecular evolution approaches to enhance the features required for specific applications. The two main goals of this study were the development of a high-throughput screening system for chitinase activity (which could be extrapolated to other hydrolytic enzymes), and the deployment of this new method to select improved chitinase variants. We therefore cloned and expressed the Bacillus licheniformis DSM8785 chitinase A (chiA) gene in Escherichia coli BL21 (DE3) cells and generated a mutant library by error-prone PCR. We then developed a screening method based on fluorescence-activated cell sorting (FACS) using the model substrate 4-methylumbelliferyl β-d-N,N′,N″-triacetyl chitotrioside to identify improved enzymes. We prevented cross-talk between emulsion compartments caused by the hydrophobicity of 4-methylumbelliferone, the fluorescent product of the enzymatic reaction, by incorporating cyclodextrins into the aqueous phases. We also addressed the toxicity of long-term chiA expression in E. coli by limiting the reaction time. We identified 12 mutants containing 2–8 mutations per gene resulting in up to twofold higher activity than wild-type ChiA.

Synthesis of 2,5-furandicarboxylic acid-enriched-chitosan for anti-inflammatory and metal ion uptake

The main aim of the present study is to synthesize a hitherto unreported polymer of chitosan (CS) and 2,5-furandicarboxylic acid (FDCA) derived from renewable biomass resources. For this purpose, CS was chosen which had -NH₂ groups as abundant active sites. Synthesis of 2,5-furandicarboxylic acid-enriched-chitosan polymer (CS-FDCA) was carried out by reaction involving EDC-NHS coupling reagents. The structure of CS-FDCA polymer was confirmed by various characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (¹H NMR), X-ray powder diffraction (XRD), high resolution-field emission scanning electron microscope (HR-FESEM), and thermogravimetric analysis (TGA). Moreover, CS and CS-FDCA were scrutinized to examine their efficacies towards ameliorate inflammation via detection of lipopolysaccharide (LPS) induced nitric oxide (NO) production. As compared to CS, CS-FDCA with low concentration (1.0 μM) exhibited the better efficacy to reduce the NO production. Furthermore, CS-FDCA polymer showed high as 12.6% of Cu²⁺ ion uptake while CS showed 9.2% of Cu²⁺ ion uptake. Overall, it can be inferred that CS-FDCA polymer is expected to be used for biomedical application and for the removal of metal contaminants from industrial wastewater.

Fish Waste: From Problem to Valuable Resource

Following the growth of the global population and the subsequent rapid increase in urbanization and industrialization, the fisheries and aquaculture production has seen a massive increase driven mainly by the development of fishing technologies. Accordingly, a remarkable increase in the amount of fish waste has been produced around the world; it has been estimated that about two-thirds of the total amount of fish is discarded as waste, creating huge economic and environmental concerns. For this reason, the disposal and recycling of these wastes has become a key issue to be resolved. With the growing attention of the circular economy, the exploitation of underused or discarded marine material can represent a sustainable strategy for the realization of a circular bioeconomy, with the production of materials with high added value. In this study, we underline the enormous role that fish waste can have in the socio-economic sector. This review presents the different compounds with high commercial value obtained by fish byproducts, including collagen, enzymes, and bioactive peptides, and lists their possible applications in different fields.