Chemical composition of snow crab shells (Chionoecetes opilio) Composición química del caparazón del cangrejo de las nieves (Chionoecetes opilio)

Exploring the Sustainable Utilization of Deep Eutectic Solvents for Chitin Isolation from Diverse Sources

Deep eutectic solvents (DES) represent an innovative and environmentally friendly approach for chitin isolation. Chitin is a natural nitrogenous polysaccharide, characterized by its abundance of amino and hydroxyl groups. The hydrogen bond network in DES can disrupt the crystalline structure of chitin, facilitating its isolation from bioresources by dissolving or degrading other components. DES are known for their low cost, natural chemical constituents, and recyclability. Natural deep eutectic solvents (NADES), a subclass of DES made from natural compounds, offer higher biocompatibility, biodegradability, and the lowest biotoxicity, making them highly promising for the production of eco-friendly chitin products. This review summarized studies on chitin isolation by DES, including reviews of biomass resources, isolation conditions (raw materials, DES compositions, solid-liquid ratios, temperature, and time), and the physicochemical properties of chitin products. Consequently, we have concluded that tailoring an appropriate DES-based process on the specific composition of the raw material can notably improve isolation efficiency. Acidic DES are particularly effective for extracting chitin from materials with high mineral content, such as crustacean bio-waste; for instance, the choline chloride-lactic acid DES achieved purity levels comparable to those of commercial chemical methods. By contrast, alkaline DES are better suited for chitin isolation from protein-rich sources, such as squid pens. DES facilitate calcium carbonate removal through H+ ion release and leverage unique hydrogen bonding interactions for efficient deproteination. Among these, potassium carbonate-glycerol DES have demonstrated optimal efficacy. Nonetheless, further comprehensive research is essential to evaluate the environmental impact, economic feasibility, and safety of DES application in chitin production.

Waterborne amino acids: uptake and functional roles in aquatic animals

Dissolved organic matter is a ubiquitous component of freshwater and marine environments, and includes small nutrient molecules, such as amino acids, which may be available for uptake by aquatic biota. Epithelial transporters, including cotransporters, uniporters and antiporters, facilitate the absorption of dissolved amino acids (often against concentration gradients). Although there is a lack of mechanistic and molecular characterization of such transporters, pathways for the direct uptake of amino acids from the water appear to exist in a wide range of marine phyla, including Porifera, Cnidaria, Platyhelminthes, Brachiopoda, Mollusca, Nemertea, Annelida, Echinodermata, Arthropoda and Chordata. In these animals, absorbed amino acids have several putative roles, including osmoregulation, hypoxia tolerance, shell formation and metabolism. Therefore, amino acids dissolved in the water may play an important, but overlooked, role in aquatic animal nutrition.

Phosphate removal from aqueous solution using calcium-rich biochar prepared by the pyrolysis of crab shells

Phosphorus is one of the main pollutants that cause water pollution, and phosphorus is a one-way cycle in the environment, and phosphorus resources will face exhaustion in the next 100 years. Therefore, the recovery and reuse of phosphorus resources have become very important. This article presents a study concerning the removal of phosphate from an aqueous solution by using a calcium-rich biochar prepared by pyrolysis of crab shells. The experimental results show that the optimal pyrolysis temperature of crab shells is 500 ℃, named CSB500, which is more conducive to the adsorption of phosphate. The process of phosphate adsorption conforms to the quasi-second-order kinetics and Freundlich model. On the other hand, the Langmuir isotherm model shows that when the reaction conditions are 25 ℃, 30 ℃, and 35 ℃, the maximum adsorption capacity of CSB500 for phosphate is 164.32 mg/g, 170.47 mg/g, and 209.35 mg/g, respectively. The characterization results show that the overall structure of CSB500 is good, the specific surface area is large, and the main component is calcium carbonate. The potential mechanisms of action in the process of phosphate adsorption may be electrostatic attraction, surface chemical precipitation, ligand exchange, and complexation.

Elemental composition of three-spot swimming crab Portunus sanguinolentus (Herbst, 1783) shell from the coasts of Sindh and Balochistan, Pakistan

The present study aimed to investigate the elemental composition of the hard shell of the three-spot swimming crab, Portunus sanguinolentus, collected from the coasts of Pakistan. Thirty crab shells were collected and divided into three groups considering their size. The element detection was performed by energy-dispersive X-ray spectroscopy with scanning electron microscope (SIM/EDAX). The mean concentration of carbon, oxygen, calcium, copper, magnesium, and phosphorus observed in the shell of P. sanguinolentus was 13.63 ± 6.21%, 46.25 ± 12.62%, 34.39 ± 18.33%, 3.19 ± 1.25%, 1.15 ± 0.99%, and 1.39 ± 0.51%, respectively. The concentration pattern of these observed elements in P. sanguinolentus shells was found in the following order: O > Ca > C > Cu > P > Mg. To compare among the three groups of shells, the highest concentration of calcium (54.60%) was obtained in large-sized shell groups, which was significantly different from the other groups (p < 0.05). A high concentration of copper was found to be accumulated in the large-sized (3.55%) and medium-sized (4.21%) shell groups, which was significantly higher than in small-sized shell groups (p < 0.05). In the case of the large-sized shell group, the mean concentrations of magnesium and phosphorus were significantly lower than the medium-sized shell group (p < 0.05). The results indicate that crab shells could act as a good bio-sorbent for several minerals in its ecosystem. P. sanguinolentus shell is very rich in calcium, magnesium, and phosphorus. Extraction of calcium, magnesium, and phosphorus from P. sanguinolentus shells could be profitable for biofertilizer and pharmaceutical industries.

Comprehensive lipidomic analysis of the lipids extracted from freshwater fish bones and crustacean shells

A comprehensive lipidomic analysis of the lipids extracted from grass carp bones, black carp bones, shrimp shells, and crab shells was performed in this study. First, HPLC analysis revealed that the lipids extracted from shrimp and crab shells contained 60.65% and 77.25% of diacylglycerols, respectively. Second, GC-MS analysis identified 18 fatty acid species in the lipids extracted from fish bones and crustacean shells, in which polyunsaturated fatty acids (PUFAs) were highly enriched. PUFAs were present at 45.43% in the lipids extracted from shrimp shells. Notably, the lipids extracted from shrimp and crab shells contained a considerable amount of eicosapentaenoic acids and docosahexaenoic acids. Finally, multidimensional mass spectrometry-based shotgun lipidomics showed that various lipids including acetyl-L-carnitine, sphingomyelin (SM), lysophosphatidylcholine, and phosphatidylcholine (PC) were all identified in the lipid samples, but PC and SM were the most abundant. Specifically, the total content of PC in shrimp shells was as high as 6.145 mmol/g. More than 35 species of PC were found in all samples, which were more than other lipids. This study is expected to provide a scientific basis for the application of freshwater fish bones and crustacean shells in food, medicine, and other fields.

Mycobiota on exoskeleton debris of Neohelice granulata in an alkaline-sodic salt marsh: in vitro enzyme ability at different temperatures and pH

This study analysed the mycobiota on exoskeleton debris of the crab Neohelice granulata collected from an alkaline salt marsh and assessed the in vitro enzyme ability of selected isolates at different temperatures and pH. Exoskeleton fragments were incubated in moist chambers on paper and on agar medium. Growth and enzyme ability of selected fungi were also evaluated in agar media with 0.5 % casein, 1% Tween®20, and Chitin-Azure® by the production of a halo/growth ratio. We identified 22 fungal species using both methods. Since the two isolation methods added information to one another, both ones are necessary to recover the cultivable mycobiota associated with the exoskeleton debris. All fungi showed greater levels of enzyme activity in alkaline than acid medium with Tween®20. The halo diameter on casein and chitin varied according to the fungal isolate and pH. Most fungi had a larger halo at 4°C than at the other temperatures tested. Clonostachys rosea showed the greatest activity in all media at 4ºC. We conclude that exoskeletons of the N. granulata are a source of fungi able to produce enzyme activities that show differences upon incubation conditions to which they are cultivated such as ones including specific temperatures and pH values.

Chemical Proprieties of Biopolymers (Chitin/Chitosan) and Their Synergic Effects with Endophytic Bacillus Species: Unlimited Applications in Agriculture

Over the past decade, reckless usage of synthetic pesticides and fertilizers in agriculture has made the environment and human health progressively vulnerable. This setting leads to the pursuit of other environmentally friendly interventions. Amongst the suggested solutions, the use of chitin and chitosan came about, whether alone or in combination with endophytic bacterial strains. In the framework of this research, we reported an assortment of studies on the physico-chemical properties and potential applications in the agricultural field of two biopolymers extracted from shrimp shells (chitin and chitosan), in addition to their uses as biofertilizers and biostimulators in combination with bacterial strains of the genus Bacillus sp. (having biochemical and enzymatic properties).

Effects of crab shell extract as a coagulant on the textural and sensorial properties of tofu (soybean curd)

To find an economic use of red snow crab (Chionoecetes japonicus) shell waste, we focused on its high mineral content. To evaluate its usability as a coagulant for tofu making, the effects of the crab shell extracts on the textural and sensorial properties of the tofu samples were investigated. The crab shell powder (CSP) and ash (CSA) were used for their extract preparation, and 1%-5% acetic acid treatment led to an abundance of calcium in the resulting extracts. The tofu yields of all the acetic acid extracts were comparable with those of the commercial coagulants MgCl2 and glucono-δ-lactone (GDL). Furthermore, the results for the textural attributes and sensorial acceptability demonstrated that either the extract from CSP prepared with 3% acetic acid or the extracts from CSA prepared with 1% or 3% acetic acid could be used as coagulants, because all the values of the extracts were statistically equivalent to those of the MgCl2 and GDL (p < 0.05).

Nanofibrillation enhances the protective effect of crab shells against Fusarium wilt disease in tomato

Chitin, a polymer of N‑acetyl‑d‑glucosamine, is a beneficial material for agriculture because it enhances plant growth and disease control. Although chitin utilization is limited by handling difficulties, chitin nanofiber (CNF) can be more feasibly used since it behaves as a water-soluble material. To broaden the utilization of chitin, protein/CaCO₃/chitin nanofiber (P/Ca/CNF) and protein/chitin nanofiber (P/CNF) complexes were prepared from crab shells without using environmentally hazardous chemical in chitin purification processes. Chitin was disintegrated into nanofibers by grinder pretreatment and the subsequent use of a high-pressure water jet system. The nanofibrillation degree depended on the number of mechanical treatments applied. The addition of CNFs to soil slightly enhanced tomato growth relative to that of CNF-untreated or crushed crab shell-treated plants. Furthermore, CNFs treatment reduced the incidence of Fusarium wilt disease in tomato plants. Disease inhibition by P/Ca/CNF and P/CNF was more effective than that by crushed crab shells, and comparable to that by pure CNF. There was no significant relationship between disease reduction level and nanofibrillation degree. In conclusion, P/Ca/CNF prepared with the minimal number of steps was sufficiently able to inhibit Fusarium wilt disease in tomato, and could thus be an eco-friendly material to control plant diseases in sustainable agriculture.