Extraction and characterization of chitin from the beetle Holotrichia parallela Motschulsky

Obtaining chitin, chitosan and their melanin complexes from insects

Interest in insects as a source of valuable biologically active substances has significantly increased over the past few years. Insects serve as an alternative source of chitin, which forms up to 40% of their exoskeleton. Chitosan, a deacetylated derivative of chitin, attracts the attention of scientists due to its unique properties (sorption, antimicrobial, film-forming, wound healing). Furthermore, some insect species are unique and can be used to obtain chitin- and chitosan-melanin complexes in the later stages of ontogenesis. Due to the synergistic effect, chitosan and melanin can enhance each other's biological activity, providing a wide range of potential applications.

Exploring Simplified Methods for Insect Chitin Extraction and Application as a Potential Alternative Bioethanol Resource

Simple Summary

The studies on chitin utilization as a source for bioethanol production are still very few. The present study explores some simple methods for insect chitin extraction and application in bioethanol production. Using insect chitin in bioethanol production, may help decreasing the dependence on energy crops as a carbon source for bioethanol. Fungal strains of Mucor circinelloides were reported previously to bio-convert chitin directly to ethanol in submerged fermentation systems. In our study, we explored the bioconversion of insect chitin to bioethanol using two different strains of Mucor circinelloides in submerged fermentation systems. An insect-isolated M. circinelloides strain was found to bio-convert the extracted chitin directly to ethanol in submerged fermentation system. The source of strain isolation and the pH of the production medium were showed to influence the chitin bioconversion directly to bioethanol. All fermentation processes can be conducted easily, using the whole growing microorganism instead of using purified enzymes. These results highlight the insect biomass as a potential new, cheap and renewable source for bioethanol production simply, using a potent insect-isolated M. circinelloides strain.

Abstract

Chitin, the second most plentiful biopolymer in nature, is a major component of insect cuticle. In searching for alternative resources for fossil fuels, some fungal strains of Mucor circinelloides from an insect-source were found to produce bioethanol directly using insect chitin as a substrate. Herein, simplified methods for insect chitin extraction and application as a substrate in submerged fermentation for bioethanol production were explored. Chitin of the American cockroach (Periplaneta americana (L.)) was isolated by refluxing the cockroaches dried exoskeletons with 4% NaOH. The purity of the extracted chitin was assessed to be high when the physicochemical properties of the extracted chitin matched these of commercially available crab and shrimp samples. The extracted chitin was employed as a substrate in submerged fermentation using two strains of M. circinelloides. One of these, strains M. circinelloides 6017 showed immense potential for bioethanol production directly. It could to bio-transform 15 g/L of colloidal chitin directly to 11.22 ± 0.312 g/L of bioethanol (74% of the initial chitin mass) after 6 days of incubation. These results confirm the possibility of using insect biomass as a potential alternative resource for bioethanol production in a simple manner thus contributing to the creation of an alternate energy source.

Isolation and Molecular Identification of Two Chitinase Producing Bacteria from Marine Shrimp Shell Wastes

BACKGROUND AND OBJECTIVE

Chitinase enzymes have a various application in the field of environmental, biotechnology and medical aspects. This study aimed to the production of the chitinolytic enzymes from different species of bacteria.

MATERIALS AND METHODS

Bacterial isolation from different habitats was carried out on agar medium containing chitin as carbon and nitrogen sources. The obtained bacteria (20) were characterized and screened again in chitin broth medium.

RESULTS

Out of 20 bacterial isolate, 2 new isolates, belonged to Streptomyces laurentii SN5 and Cellulosimicrobium funkei SN20, were the most active in chitin degradation compared to the other isolates. They have been characterized for the first time for their chitinase activity. They were identified using 16S rRNA gene analysis and in the liquid medium, the 2 isolates have enzyme activities of 0.533 and 0.537 U mL-1, respectively. The maximum chitinase production was obtained when those bacterial strains were grown in Luria-Bertani (LB) broth amended with 1% colloidal chitin, for 1 day and at temperature of 30°C. The optimum pH value for chitinase production was pH 7 for both S. laurentii and C. funkei. The enzyme has been purified using Sephadex G-100 and DEAE-Cellulose chromatography column and found to have a similar molecular size of ~50 kDa.

CONCLUSION

Those two bacterial species could be used in chitinase production and in the environmental recycling of disposable chitin wastes such as chitin from shrimp shell waste.

Application status and technical analysis of chitosan-based medical dressings: a review

Chitosan has wide applications in the field of medical dressings due to its good biomedical properties. This review provides the application status and technical analysis of chitosan medical dressings. First, we introduce the source and chemical structure of chitosan. Then, we investigate the mechanism of chitosan showing different medical properties. We also show the application of supramolecular chitosan-based hydrogels in the dressing field and the formulation optimization and the preparation technology of chitosan dressings for fabricating chitosan-based dressings with various morphologies and medical functions. After that, we introduce the research process of the modification method of chitosan dressings including single modification, blending modification, crosslinking modification, etc. Finally, based on the study of the medical effects of chitosan dressings, we analyze the existing problems in the preparation process and propose corresponding solutions from the aspects of the morphology, clinical feedback effect, and future development trends. This paper can provide a reference for further studies of skin tissue engineering and the development of new chitosan medical dressings.

Chitosan has wide applications in the field of medical dressings due to its good biomedical properties.

Recent insights into the extraction, characterization, and bioactivities of chitin and chitosan from insects

Background

Insects are a living resource used for human nutrition, medicine, and industry. Several potential sources of proteins, peptides, and biopolymers, such as silk, chitin, and chitosan are utilized in industry and for biotechnology applications. Chitosan is an amino-polysaccharide derivative of chitin that consists of linear amino polysaccharides with d-glucosamine and N-acetyl-d-glucosamine units. Currently, the chief commercial sources of chitin and chitosan are crustacean shells that accumulate as a major waste product from the marine food industry. Existing chitin resources have some natural challenges, including insufficient supplies, seasonal availability, and environmental pollution. As an alternative, insects could be utilized as unconventional but feasible sources of chitin and chitosan.

Scope and approach

This review focuses on the recent sources of insect chitin and chitosan, particularly from the Lepidoptera, Coleoptera, Orthoptera, Hymenoptera, Diptera, Hemiptera, Dictyoptera, and Odonata orders. In addition, the extraction methods and physicochemical characteristics are discussed. Insect chitin and chitosan have numerous biological activities and could be used for food, biomedical, and industrial applications.

Key findings and conclusions

Recently, the invasive and harmful effects of insect species causing severe damage in agricultural crops has led to great economic losses globally. These dangerous species serve as potential sources of chitin and are underutilized worldwide. The conclusion of the present study provides better insight into the conversion of insect waste-derived chitin into value-added products as an alternative chitin source to address food security related challenges.

Extraction, Characterization, and Antimicrobial Activity of Chitosan from Horse Mussel Modiolus modiolus

Chitin and chitosan have been proved to have enormous applications in biomedical, pharmaceutical, and industrial fields. The horse mussel, Modiolus modiolus, a refuse of the fishery industries at Thondi, is a reserve of rich chitin. The aim of this work is to extract chitosan from the horse mussel and its further characterization using Fourier transform infrared spectroscopy (FTIR), micro-Raman spectroscopy, X-ray diffraction (XRD), and elemental analysis. The result of FTIR studies revealed different functional groups of organic compounds such as out-of-plane bending (564 cm^-1), C-O-C stretching (711 cm^-1), and CH₂ stretching (1174 cm^-1) in chitosan. The degree of acetylation of the extracted chitosan was observed to be 57.43%, which makes it suitable as a biopolymer for biomedical applications. Prominent peaks observed with micro-Raman studies were at 484 cm^-1 (14,264 counts/s), 2138 cm^-1 (45,061 counts/s), and 2447 cm^-1 (45,636 counts/s). XRD studies showed the crystalline nature of the polymer, and the maximum peak was observed at 20.04°. Elemental analysis showed a considerable decrease in the percentage of nitrogen and carbon upon the conversion of chitin to chitosan, while chitosan had a higher percentage of hydrogen and sulfur. The antibacterial activities of chitosan from the horse mussel were found to be efficient at a 200 μg/mL concentration against all the bacterial strains tested with a comparatively higher antibacterial activity against Escherichia coli (9 mm) and Bacillus subtilis (8 mm).

The Potential of Insects as Alternative Sources of Chitin: An Overview on the Chemical Method of Extraction from Various Sources

Chitin, being the second most abundant biopolymer after cellulose, has been gaining popularity since its initial discovery by Braconot in 1811. However, fundamental knowledge and literature on chitin and its derivatives from insects are difficult to obtain. The most common and sought-after sources of chitin are shellfish (especially crustaceans) and other aquatic invertebrates. The amount of shellfish available is obviously restricted by the amount of food waste that is allowed; hence, it is a limited resource. Therefore, insects are the best choices since, out of 1.3 million species in the world, 900,000 are insects, making them the most abundant species in the world. In this review, a total of 82 samples from shellfish—crustaceans and mollusks (n = 46), insects (n = 23), and others (n = 13)—have been collected and studied for their chemical extraction of chitin and its derivatives. The aim of this paper is to review the extraction method of chitin and chitosan for a comparison of the optimal demineralization and deproteinization processes, with a consideration of insects as alternative sources of chitin. The methods employed in this review are based on comprehensive bibliographic research. Based on previous data, the chitin and chitosan contents of insects in past studies favorably compare and compete with those of commercial chitin and chitosan—for example, 45% in Bombyx eri, 36.6% in Periostracum cicadae (cicada sloughs), and 26.2% in Chyrysomya megacephala. Therefore, according to the data reported by previous researchers, demonstrating comparable yield values to those of crustacean chitin and the great interest in insects as alternative sources, efforts towards comprehensive knowledge in this field are relevant.

Functionalization of 3D Chitinous Skeletal Scaffolds of Sponge Origin Using Silver Nanoparticles and Their Antibacterial Properties

Chitin, as one of nature's most abundant structural polysaccharides, possesses worldwide, high industrial potential and a functionality that is topically pertinent. Nowadays, the metallization of naturally predesigned, 3D chitinous scaffolds originating from marine sponges is drawing focused attention. These invertebrates represent a unique, renewable source of specialized chitin due to their ability to grow under marine farming conditions. In this study, the development of composite material in the form of 3D chitin-based skeletal scaffolds covered with silver nanoparticles (AgNPs) and Ag-bromide is described for the first time. Additionally, the antibacterial properties of the obtained materials and their possible applications as a water filtration system are also investigated.

Chitin, Characteristic, Sources, and Biomedical Application

BACKGROUND

Chitin stands at second, after cellulose, as the most abundant polysaccharide in the world. Chitin is found naturally in marine environments as it is a crucial structural component of various marine organisms.

METHODS

Different amounts of waste chitin and chitosan can be discovered in the environment. Chitinase producing microbes help to hydrolyze chitin waste to play an essential function for the removal of chitin pollution in the Marine Atmosphere. Chitin can be converted by using chemical and biological methods into prominent derivate chitosan. Numerous bacteria naturally have chitin degrading ability.

RESULTS

Chitin shows promise in terms of biocompatibility, low toxicity, complete biodegradability, nontoxicity, and film-forming capability. The application of these polymers in the different sectors of biomedical, food, agriculture, cosmetics, pharmaceuticals could be lucrative. Moreover, the most recent achievement in nanotechnology is based on chitin and chitosan-based materials.

CONCLUSION

In this review, we examine chitin in terms of its natural sources and different extraction methods, chitinase producing microbes and chitin, chitosan together with its derivatives for use in biomedical and agricultural applications.

Electrochemical Approach for Isolation of Chitin from the Skeleton of the Black Coral Cirrhipathes sp. (Antipatharia)

The development of novel and effective methods for the isolation of chitin, which remains one of the fundamental aminopolysaccharides within skeletal structures of diverse marine invertebrates, is still relevant. In contrast to numerous studies on chitin extraction from crustaceans, mollusks and sponges, there are only a few reports concerning its isolation from corals, and especially black corals (Antipatharia). In this work, we report the stepwise isolation and identification of chitin from Cirrhipathes sp. (Antipatharia, Antipathidae) for the first time. The proposed method, aiming at the extraction of the chitinous scaffold from the skeleton of black coral species, combined a well-known chemical treatment with in situ electrolysis, using a concentrated Na₂SO₄ aqueous solution as the electrolyte. This novel method allows the isolation of α-chitin in the form of a microporous membrane-like material. Moreover, the extracted chitinous scaffold, with a well-preserved, unique pore distribution, has been extracted in an astoundingly short time (12 h) compared to the earlier reported attempts at chitin isolation from Antipatharia corals.

Extraction and Physicochemical Characterization of Chitin from Cicada orni Sloughs of the South-Eastern French Mediterranean Basin

Chitin is a structural polysaccharide of the cell walls of fungi and exoskeletons of insects and crustaceans. In this study, chitin was extracted, for the first time in our knowledge, from the Cicada orni sloughs of the south-eastern French Mediterranean basin by treatment with 1 M HCl for demineralization, 1 M NaOH for deproteinization, and 1% NaClO for decolorization. The different steps of extraction were investigated by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM). Results demonstrated that the extraction process was efficiently performed and that Cicada orni sloughs of the south-eastern French Mediterranean basin have a high content of chitin (42.8%) in the α-form with a high degree of acetylation of 96% ± 3.4%. These results make Cicada orni of the south-eastern French Mediterranean basin a new and promising source of chitin. Furthermore, we showed that each step of the extraction present specific characteristics (for example FTIR and XRD spectra and, consequently, distinct absorbance peaks and values of crystallinity as well as defined values of maximum degradation temperatures identifiable by TGA analysis) that could be used to verify the effectiveness of the treatments, and could be favorably compared with other natural chitin sources.

Usage of natural chitosan membrane obtained from insect corneal lenses as a drug carrier and its potential for point of care tests

Chitosan is an indispensable biopolymer for use as a drug carrier thanks to its non-toxic, biodegradable, biocompatible, antimicrobial, and anti-oxidative nature. In previous studies, chitosan was first dissolved into weak acids and formed into gel, then used for carrying pharmaceutically active compounds such as nanoparticles, capsules, composites, and films. Using the produced chitosan gel after dissolving it in weak acids has advantages, such as ease of processing for loading the required amount of active substance and making the desired shape and size. However, dissolved chitosan loses some of its natural properties such as fibrous structure, crystallinity, and thermal stability. In this study, for the first time, three-dimensional chitosan lenses obtained from an insect's (Tabanus bovinus) compound eyes, with the original shape intact, were tested as a drug carrier. A model drug, quercetin, was loaded into chitosan membrane, and its release profile was examined. Also, a point-of-care test was conducted for both chitin and chitosan membranes. Chitin and chitosan membranes obtained from insect corneal lenses were characterized by using FTIR, TGA, elemental analysis, and surface wettability analysis as well as stereo, binocular, and scanning electron microscopies. It was observed that chitosan membrane could be used as a drug carrier material. Both chitin and chitosan membranes will be improved for lateral flow assay, and these membranes can be tested for other bioengineering applications in further studies.

Chitin and Chitinases: Biomedical And Environmental Applications of Chitin and its Derivatives

Disposal of chitin wastes from crustacean shell can cause environmental and health hazards. Chitin is a well known abundant natural polymer extracted after deproteinization and demineralization of the shell wastes of shrimp, crab, lobster, and krill. Extraction of chitin and its derivatives from waste material is one of the alternative ways to turn the waste into useful products. Chitinases are enzymes that degrade chitin. Chitinases contribute to the generation of carbon and nitrogen in the ecosystem. Chitin and chitinolytic enzymes are gaining importance for their biotechnological applications. The presence of surface charge and multiple functional groups make chitin as a beneficial natural polymer. Due to the reactive functional groups chitin can be used for the preparation of a spectrum of chitin derivatives such as chitosan, alkyl chitin, sulfated chitin, dibutyryl chitin and carboxymethyl chitin for specific applications in different areas. The present review is aimed to summarize the efficacy of the chitinases on the chitin and its derivatives and their diverse applications in biomedical and environmental field. Further this review also discusses the synthesis of various chitin derivatives in detail and brings out the importance of chitin and its derivatives in biomedical and environmental applications.

Bioprocessing of shrimp wastes to obtain chitosan and its antimicrobial potential in the context of ethanolic fermentation against bacterial contamination

This study investigated the bioprocessing of shrimp wastes to obtain chitin and its deacetylated product chitosan by a fermentation process mediated by Lactobacillus plantarum. The concentrations of glucose, bacterial inoculum, and shrimp wastes in the Man, Rogosa and Sharpe medium were optimized for the fermentation process performed in shake flasks to achieve the maximum titratable acidity to obtain chitin. The experiments were scaled up in a 700-mL working volume bioreactor, and the resulting chitin was deacetylated by the autoclave method. The bioextracted chitosan was characterized (Fourier transform infrared spectroscopy [FTIR], deacetylation degree, and molecular weight) and evaluated for its antimicrobial effects by comparing it with a commercial chitosan sample in the context of the ethanolic fermentation process for fuel alcohol production. The effect of chitosan on such a fermentation process has not been determined yet. The bacterial contaminant Lactobacillus fermentum and the main agent of ethanolic fermentation Saccharomyces cerevisiae were cultured in semi-synthetic medium and co-cultured in sugarcane juice to verify the effect of chitosan on their growth. The bioextracted chitosan (molecular weight 4.0 × 10⁵ g mol^-1 and deacetylation degree 80%) was comparable to commercial chitosan, although higher concentrations of the former were required to achieve similar antimicrobial activities. Both commercial and bioextracted chitosan samples exhibited antimicrobial activity against S. cerevisiae and L. fermentum, but the concentration that caused the inhibition of yeast growth was almost tenfold higher than for the bacterium. Moreover, bioextracted chitosan showed no yeast inhibition or lethality in the range of 0.0075-0.96% while for the bacterium, growth inhibition occurred in concentrations varying from 0.24 to 0.48% and lethality of more than 99% at 0.96%. These results indicate the potential use of chitosan and especially of bioextracted chitosan in the bioethanol industry as a safer and more natural approach to combat unwanted bacterial contamination.

Removal of bromophenol blue anionic dye from water using a modified exuviae of Hermetia illucens larvae as biosorbent

Organic dyes originating from liquid effluents from the textile industries are harmful to the environment. They are toxic and reduce the penetration of light into aquatic environments. In this study, a biosorbent was produced from the exuviae of Hermetia illucens (Linnaeus) larvae and used to remove organic anionic dyes from an aqueous medium. The solids were characterized in terms of thermal stability, chemical structure, morphology, and porosity using thermogravimetric (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and N₂ adsorption-desorption. There were studied the effects of pH and dosage of the adsorbent on the adsorption of the bromophenol blue dye, used as a model molecule. The adsorption kinetics was studied with Lagergren's pseudo-first-order rate model. The maximum adsorbed amount was 571 mg g^-1 according to Langmuir's model. The adsorption process was evaluated as exothermic and spontaneous and was classified as physical adsorption. The prepared biosorbent was tested in five consecutive adsorption cycles achieving 99% dye removal at each stage. This demonstrated the maintenance of adsorption efficiency and desorption capacity. These results suggest that prepared biosorbent have potential applications in the treatment of effluents from textile industries.

Microbial extraction of chitin from seafood waste using sugars derived from fruit waste-stream

Chitin and chitosan are natural amino polysaccharides that have exceptional biocompatibility in a wide range of applications such as drug delivery carriers, antibacterial agents and food stabilizers. However, conventional chemical extraction methods of chitin from marine waste are costly and hazardous to the environment. Here we report a study where shrimp waste was co-fermented with Lactobacillus plantarum subsp. plantarum ATCC 14917 and Bacillus subtilis subsp. subtilis ATCC 6051 and chitin was successfully extracted after deproteinization and demineralization of the prawn shells. The glucose supplementation for fermentation was replaced by waste substrates to reduce cost and maximize waste utilization. A total of 10 carbon sources were explored, namely sugarcane molasses, light corn syrup, red grape pomace, white grape pomace, apple peel, pineapple peel and core, potato peel, mango peel, banana peel and sweet potato peel. The extracted chitin was chemically characterized by Fourier Transform Infrared Spectroscopy (FTIR) to measure the degree of acetylation, elemental analysis (EA) to measure the carbon/nitrogen ratio and X-ray diffraction (XRD) to measure the degree of crystallinity. A comparison of the quality of the crude extracted chitin was made between the different waste substrates used for fermentation and the experimental results showed that the waste substrates generally make a suitable replacement for glucose in the fermentation process. Red grape pomace resulted in recovery of chitin with a degree of deacetylation of 72.90%, a carbon/nitrogen ratio of 6.85 and a degree of crystallinity of 95.54%. These achieved values were found to be comparable with and even surpassed commercial chitin.

Statistical Optimization for Coproduction of Chitinase and Beta 1, 4-Endoglucanase by Chitinolytic Paenibacillus elgii PB1 Having Antifungal Activity

A bacterial strain PB1 with antagonistic activity against pathogenic fungi was isolated from marine soil and was identified as Paenibacillus elgii based on phenotypic and genotypic characterization. The isolate showed good antifungal activity against "Aspergillus niger (MTCC 282), Trichophyton rubrum (MTCC 791), Microsporum gypseum (MTCC 2819), Candida albicans (MTCC 227), and Saccharomyces cerevisiae (MTCC 170)". Chitinase and beta 1, 4-endoglucanase are known for their capability to degrade fungal cell wall, thus we analyzed its productivity in PB1 strain using Plackett-Burman and Central Composite Design. The factors that affect the productivity of chitinase and beta 1, 4-endoglucanase were identified and optimized. A 7.77-fold increase (3.157 to 24.53 ± 1.33 U/mL) in chitinase and 7.422-fold increase (6.476 to 48.066 ± 0.676 U/mL) in beta 1, 4-endoglucanase versus basal medium was achieved. Chitinase and beta 1, 4-endoglucanase produced by Paenibacillus elgii strain PB1 represents the new source for biotechnological, medical, and agricultural applications.

Nikalje A, Fraga-López F. Extraction and Physicochemical Characterization of Chitin Derived from the Asian Hornet, Vespa velutina Lepeletier 1836 (Hym.: Vespidae)

Fifteen years ago, at least one multimated female yellow-legged Asian hornet (Vespa velutina Lepeletier 1836) arrived in France, which gave rise to a pan-European invasion. In this study, the isolation and characterization of chitin (CHI) that was obtained from Vespa velutina (CHI_VV) is described. In addition, an easy procedure is carried out to capture the raw insect, selectively and with high rates of success. The chitin contents of dry VV was observed to be 11.7%. Fourier transform infrared spectroscopy (FTIR), solid-state NMR (ssNMR), elemental analysis (EA), scanning electron microscopy (SEM), and thermogravimetric analysis (TG) characterized the physicochemical properties of CHI_VV. The obtained CHI_VV is close to pure (43.47% C, 6.94% H, and 6.85% N), and full acetylated with a value of 95.44%. Additionally, lifetime and kinetic parameters such as activation E and the frequency factor A using model-free and model-fitting methods, were determined. For CHI_VV the solid state mechanism that follows the thermodegradation is of type F2 (random nucleation around two nuclei). The invasive Asian hornet is a promising alternative source of CHI, based on certain factors, such as the current and probable continued abundance of the quantity and quality of the product obtained.

Energía calórica, biomasa y estructura de los macroinvertebrados acuáticos en la reserva La Nitrera, Concordia, Antioquia, Colombia

El embalse La Nitrera se encuentra localizado a 2140 m.s.n.m. en el municipio de Concordia, departamento de Antioquia (Colombia) y es la única fuente de abastecimiento de agua del municipio. La operación de un embalse sobre un sistema lótico afecta la estructura y ensamblaje de sus ecosistemas acuáticos. Esta investigación tuvo como propósito analizar la distribución de la biomasa de los macroinvertebrados acuáticos antes y después del embalse, con el fin de determinar el impacto de este sobre las comunidades hidrobiológicas. Para tal fin, se analizaron las variables hidrobiológicas en época seca, de lluvia y en diferentes periodos de transición entre el año 2016 y 2017. Se investigaron cuatro estaciones de monitoreo, realizando la determinación, conteo y definiendo el rol trófico de los macroinvertebrados acuáticos, además de un análisis termogravimétrico (TGA) de la biomasa. Con la información obtenida, se construyó un modelo trófico y se calculó la pérdida de energía calórica disponible de la biomasa (TGA). Los resultados evidenciaron que las comunidades de macroinvertebrados acuáticos presentan una modularidad similar entre ellas en las estaciones antes del embalse, y una modularidad diferente en la estación después del embalse. A través del índice de modularidad (modelo Ghepi) y el análisis TGA, se logró establecer que el embalse altera la cadena trófica de las comunidades de macroinvertebrados acuáticos.

Effect of heat processing on the nutrient composition, colour, and volatile odour compounds of the long-horned grasshopper Ruspolia differens serville

Heat processing is commonly used to prepare edible insects for consumption. This study aimed at determining the effect of boiling and subsequent oven roasting on Ruspolia differens' nutrient composition, colour and odor compounds. Boiling leads to: a significant increase in protein and decrease in fat content on a dry matter basis; a minimal influence on its amino and fatty acids profile; a significant reduction in its ash content due to leaching of phosphorus, potassium and sodium; a significant increase in iron, zinc, copper, manganese and calcium content; and a fivefold reduction in the amount of vitamin B12. Roasting leads to a relative increase in the amount of calcium and trace mineral elements but doesn't affect other nutrients. Roasting results into a more uniform colour intensity when green and brown polymorphs are roasted together. Lipid oxidation is responsible for the colour and aroma of heat processed R. differens.

Effect of particle sizes on the kinetics of demineralization of snail shell for chitin synthesis using acetic acid

This study considers the kinetics of snail shells demineralization process using acetic acid. It was washed, sundried then ground into four different particle sizes. The ranges of particle sizes are 6.3-4.75 mm, 4.75-2 mm, 2 - 1 mm, and 600 -300 μm. The shells were first deproteinized with sodium hydroxide solution thereafter they were demineralized using 1.2 M acetic acid solution. Kinetics of demineralization of the snail shells was performed by XRF analysis of the chitin produced at 5, 10, 15, 20, 25, 30, and 35 min. The kinetic results show that mechanism of chitin formation from snail shell occurs through the chemical reaction controlled (CRC) model of the shrinking core model for particle sizes between 6.3 - 4.75 mm, 4.75-2 mm, and 2-1 mm particle sizes while Fluid Film Diffusion (FFD) model was observed for the smaller range of 600-300 μm particle sizes. The surface morphology and the FTIR analysis of the synthesized chitin were typical of those obtained for earlier studies.

Study on the "Glutamic Acid-Enzymolysis" Process for Extracting Chitin from Crab Shell Waste and its By-Product Recovery

Chitin is the second-most abundant bioresource and widely used in the food, agricultural, biomedicine, and other industries. However, under the mutual restriction of extraction cost and environmental protection, it is relatively difficult to prepare chitin from natural sources by pure separation. The aim of this study is to extract chitin from fresh crab shell waste by decalcification (DC) and deproteinization (DP) using glutamic acid and alkaline protease. The optimum technological conditions for DC and DP were as follows: (1) 5% (w/v) glutamic acid solution was used as decalcifying agent, the ratio of material to liquid was 1:10 (m/v), and the ash content in chitin was 0.83 ± 0.027% after decalcification at 75° C for 12 h. (2) Using alkaline protease as enzymatic hydrolyzer, 1500 U of alkaline protease was added per gram of crab shell. Under the conditions of material-liquid ratio of 1:10 (m/v) and pH value of hydrolysate of 9.0, N content in chitin was 6.63 ± 0.10% after 6 h of enzymatic hydrolysis at 55° C. And the extraction rate of chitin was 92.25 ± 0.51%. As a decalcifying agent, glutamic acid could be recycled with a recovery rate of 77.42 ± 2.16%. Calcium carbonate in crab shell was converted into calcium hydrogen phosphate by calcium glutamate, and protein into amino acids and polypeptides, which could be used as feed additives. The "glutamic acid-enzymolysis" for extracting chitin from crab shell is a relatively closed process, which has the advantages of mild reaction, greatly reducing the discharge of three wastes and high comprehensive utilization rate of raw materials.

A potent chitin-hydrolyzing enzyme from Myrothecium verrucaria affects growth and development of Helicoverpa armigera and plant fungal pathogens

Chitin, a crucial structural and functional component of insects and fungi, serves as a target for pest management by utilizing novel chitinases. Here, we report the biocontrol potential of recombinant Myrothecium verrucaria endochitinase (rMvEChi) against insect pest and fungal pathogens. A complete ORF of MvEChi (1185 bp) was cloned and heterologously expressed in Escherichia coli. Structure based sequence alignment of MvEChi revealed the presence of conserved domains SXGG and DXXDXDXE specific for GH-18 family, involved in substrate binding and catalysis, respectively. rMvEChi (46.6 kDa) showed optimum pH and temperature as 7.0 and 30 °C, respectively. Furthermore, rMvEChi remained stable within the pH range of 6.0 to 8.0 and up to 40 °C. rMvEChi exhibited k_cat/K_m values of 129.83 × 10³ [(g/L)^-1 s^-1] towards 4MU chitotrioside. Hydrolysis of chitooligosaccharides with various degrees of polymerization (DP) using rMvEChi indicated the release of DP2 as main end product with order of reaction as DP6 > DP5 > DP4 > DP3. Bioassay of rMvEChi against Helicoverpa armigera displayed potent anti-feedant activity and induced mortality. In vitro antifungal activity against plant pathogenic fungi (Ustilago maydis and Bipolaris sorokiniana) exhibited significant inhibition of mycelium growth. These results suggest that MvEChi has significant potential in enzyme-based pest and pathogen management.

Schistocerca piceifrons piceifrons (Orthoptera: Acrididae) as a Source of Compounds of Biotechnological and Nutritional Interest

The Central American locust, Schistocerca piceifrons piceifrons (Walker) is a major agricultural pest in Mexico and Central America. Control measures against this pest have generated much environmental damage and substantial financial costs because chemical insecticides are used. Yet various Orthoptera species also appear to be a potential source of nutrients and a source of bioactive metabolites. Here, we studied the presence of secondary metabolites in the adult stage of S. p. piceifrons by applying different colorimetric techniques. Adults were collected from the southern region of Tamaulipas, Mexico, during September-December 2017. These samples were subjected to sequential processes of eviscerating, drying, pulverizing, extracting, and detecting of metabolites. Extractions were carried out in water, 50% ethanol, and absolute ethanol. The presence of phenolic compounds, alkaloids, tannins, saponins, flavonoids, and quantity of antioxidants against the DPPH (2, 2-diphenyl-1-picrylhydrazyl) and ABTS (2, 2'-azino-bis, 3-ethylbenzothiazoline-6-sulfonic acid) radicals were determined and reported. Proximate analysis showed that S. p. piceifrons has a high protein content (80.26%), low fat content (6.21%), and fiber content (12.56%) similar to other Orthoptera species. Chitin and chitosan contents of S. p. piceifrons were 11.88 and 9.11%, respectively; the recovery percentage of chitosan from chitin was 76.71%. Among the Orthoptera, the protein content of this pest is among the highest while its contents of chitin and chitosan are similar to those of other insect species (e.g., Bombix mori Linnaeus [Lepidoptera: Bombycidae]). Our results suggest this pest species is a potential source of bioactive compounds of biotechnological interest for use by pharmaceutical and food industries.

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

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

An Archaeal Chitinase With a Secondary Capacity for Catalyzing Cellulose and Its Biotechnological Applications in Shell and Straw Degradation

Numerous thermostable enzymes have been reported from the hyperthermophilic archaeon Thermococcus kodakarensis KOD1, which made it an attractive resource for gene cloning. This research reported a glycosyl hydrolase (Tk-ChiA) form T. Kodakarensis with dual hydrolytic activity due to the presence of three binding domains with affinity toward chitin and cellulose. The Tk-ChiA gene was cloned and expressed on Pichia pastoris GS115. The molecular weight of the purified Tk-ChiA is about 130.0 kDa. By using chitosan, CMC-Na and other polysaccharides as substrates, we confirmed that Tk-ChiA with dual hydrolysis activity preferably hydrolyzes both chitosan and CMC-Na. Purified Tk-ChiA showed maximal activity for hydrolyzing CMC-Na at temperature 65°C and pH 7.0. It showed thermal stability on incubation for 4 h at temperatures ranging from 70 to 80°C and remained more than 40% of its maximum activity after pre-incubation at 100°C for 4 h. Particularly, Tk-ChiA is capable of degrading shrimp shell and rice straw through scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) analysis. The main factors affecting shell and straw degradation were determined to be reaction time and temperature; and both factors were optimized by central composite design (CCD) of response surface methodology (RSM) to enhance the efficiency of degradation. Our findings suggest that Tk-ChiA with dual thermostable hydrolytic activities maybe a promising hydrolase for shell and straw waste treatment, conversion, and utilization.

Purification and biochemical characterization of a novel thermostable and halotolerant subtilisin SAPN, a serine protease from Melghiribacillus thermohalophilus Nari2AT for chitin extraction from crab and shrimp shell by-products

The present study investigates the purification and biochemical characterization of a novel extracellular serine alkaline protease, subtilisin (called SAPN) from Melghiribacillus thermohalophilus Nari2A^T. The highest yield of protease (395 IU/g) with white shrimp shell by-product (40 g/L) as a unique source of nutriments in the growth medium was achieved after 52 h at 55 °C. The monomeric enzyme of about 30 kDa was purified to homogeneity by ammonium sulfate fractionation, heat treatment, followed by sequential column chromatographies. The optimum pH and temperature values for subtilisin activity were pH 10 and 75 °C, respectively, and half lives of 9 and 5 h at 80 and 90 °C, respectively. The sequence of the 25 NH₂-terminal residues pertaining of SAPN exhibited a high homology with those of Bacillus subtilisins. The inhibition by DFP and PMSF indicates that this enzyme belongs to the serine proteases family. SAPN was found to be effective in the deproteinization (DDP %) of blue swimming crab (Portunus segnis) and white shrimp (Metapenaeus monoceros) by-products, with a degree of 65 and 82%, respectively. The commercial and the two chitins obtained in this work showed a similar peak pattern in Fourier-Transform Infrared (FTIR) analysis, suggesting that SAPN is suitable for the bio-production of chitin from shell by-products.

The Effects of Diet Formulation on the Yield, Proximate Composition, and Fatty Acid Profile of the Black Soldier Fly (Hermetia illucens L.) Prepupae Intended for Animal Feed

Simple Summary

Mass rearing of the black soldier fly to be used as feed is still at an early stage. Among the different issues, larval feeding and nutrition of this species are the most relevant ones from a practical standpoint. For example, testing four different diets, we found that this insect can be efficiently reared on wheat byproducts in place of cornmeal and that using diets richer in carbohydrates or proteins can negatively affect protein accumulation, larval development, and survivorship. Accumulation of unsaturated fats in black soldier fly prepupae is a matter of great interest, and it was found to be directly dependent on the amount of these fats in the rearing substrates. By appropriately mixing different food byproducts as diet ingredients, our research suggests that black soldier fly prepupae meal suitable for the feed formulation can be obtained.

Abstract

The black soldier fly (BSF; Hermetia illucens L.) is a very promising insect species due to the ability to convert low-value substrates in highly nutrient feed. This work aimed to study the effect of three nominally isoenergetic diets containing plant ingredients such as barley, alfalfa, and wheat byproducts, formulated to be higher in nonfiber carbohydrates (TMD1), fibers (TMD2), and protein (TMD3) in comparison to an extensively genetic modified cereal (cornmeal)-based diet (C), on the growth, yield, and nutritive traits of BSF prepupae (BSFPs). Three growing trials with four biological replicates were carried out. Proximate and fatty acid analyses were performed on the diets and BSFPs. Feed conversion ratios (FCR), dry matter and nutrient yields, and apparent concentration factors (aBCF) for fatty acids (FAs) were calculated. Diet formulation had a substantial effect on the survival, development rate, and larval yield, but the FCR was unaffected. The BSFPs fed TMD3 did not result in a higher crude protein content in comparison to the C or TMD2 diets. Despite the leveled fat content of the diets, BSFPs reared on TMD1 were highest in fat, saturated FA, and fat yield. An apparent bioconcentration factor (aBCF) value lower than unity that was found for the unsaturated FA suggests that the BSFPs inefficiently absorb them from the diet or possibly turn them into saturated FA. However, the unsaturated FA accumulation in BSFPs depended on the levels that were found in the diet, which suggested some possibilities for the FA profile modulation. Overall, the TMD2 performed well despite the low-value of its main ingredients and high fiber content and can be considered to be a feasible option for the mass rearing of BSFPs that are intended for animal feed.

Extraction and characterization of chitin from sea snail Conus inscriptus (Reeve, 1843)

The chitin was extracted from C. inscriptus and the structure was elucidated. The yield of the C. inscriptus shell chitin was 21.65% on dry weight basis. The ash and moisture content of the chitin was 1.2 and 6.50%. The result of the molecular analysis of the chitin revealed low molecular weight (25 kDa). The crystalline structure (XRD), functional group (FT-IR), elemental analysis (EDAX), surface morphology (SEM) and thermal stability (TG/DTA) results confirmed conus chitin was in α-crystalline form. The crystalline index value (CrI) of the conus chitin was 82.13%. The FT-IR analysis of the conus chitin displayed two bands at around 1730 and 1628 cm^-1. SEM investigation of the commercial chitin and C. inscriptus chitin exposed that it was composed of nanopore and nanofibre structures. Further, the thermal stability of the conus chitin was close to the thermal stability of the commercial chitin. The results show that processing of C. inscriptus shell can lead to a high quality chitin, useful for a broad range of applications.