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.

Molecular Characterization of Four Alkaline Chitinases from Three Chitinolytic Bacteria Isolated from a Mudflat

Four chitinases were cloned and characterized from three strains isolated from a mudflat: Aeromonas sp. SK10, Aeromonas sp. SK15, and Chitinibacter sp. SK16. In SK10, three genes, Chi18A, Pro2K, and Chi19B, were found as a cluster. Chi18A and Chi19B were chitinases, and Pro2K was a metalloprotease. With combinatorial amplification of the genes and analysis of the hydrolysis patterns of substrates, Chi18A and Chi19B were found to be an endochitinase and exochitinase, respectively. Chi18A and Chi19B belonged to the glycosyl hydrolase family 18 (GH18) and GH19, with 869 and 659 amino acids, respectively. Chi18C from SK15 belonged to GH18 with 864 amino acids, and Chi18D from SK16 belonged to GH18 with 664 amino acids. These four chitinases had signal peptides and high molecular masses with one or two chitin-binding domains and, interestingly, preferred alkaline conditions. In the activity staining, their sizes were determined to be 96, 74, 95, and 73 kDa, respectively, corresponding to their expected sizes. Purified Chi18C and Chi18D after pET expression produced N,N′-diacetylchitobiose as the main product in hydrolyzing chitooligosaccharides and colloidal chitin. These results suggest that Chi18A, Chi18C, and Chi18D are endochitinases, that Chi19B is an exochitinase, and that these chitinases can be effectively used for hydrolyzing natural chitinous sources.

Immobilization of Providencia stuartii Cells in Pumice Stone and Its Application for N-Acetylglucosamine Production

Research background. Shrimp shells contain chitin that can further be processed into N-acetylglucosamine which has been extensively used to treat joint damage. Providencia stuartii isolated form previous research has strong chitinolytic activity and may be utilized in the form of immobilized cells to be used in repeated fermentation. Pumice is a porous and rigid stone that offers superior mechanical strength, making it suitable to be used for immobilization process. Experimental approach. The research used experimental method to conduct the submerged fermentation process with different pumice stone size and pumice stone:growth medium ratio (m/V). The fermentation was carried out for 4 days at 37 C and pH of 7.0. The optimum pumice stone size and pumice stone:growth medium ratio (m/V) were used to determine the optimum fermentation cycle to produce N-acetylglucosamine. Results and conclusions. Pumice stones of 1.0×1.0×1.0 cm and pumice stone:growth medium ratio (m/V) of 1:5 were found to be the optimum conditions which successfully immobilized (89.99±1.65) % cells and produced (331.37±7.34) g/L N-acetylglucosamine. The highest N-acetylglucosamine concentration of (322.97±2.46) g/L was obtained in the first fermentation cycle which then decreased and remained stable throughout the last three cycles of fermentation. Novelty and scientific contribution. P. stuartii was a strong chitinolytic bacteria previously isolated from rotten shrimp shells and was used for the first time in immobilized form to produce N-acetylglucosamine. The findings in this research showed potential use of P. stuartii cells immobilized in pumice stone for continuous production of N-acetylglucosamine using fermentation method.

Immobilization of Providencia stuartii Cells in Papaya Trunk Wood for N-acetylglucosamine Production from Pennaeus vannamei Shrimp Shells

Highlight Research AbstractChitin is a natural compound found abundantly in shrimp shells. Chitin can be degraded to produce N-acetylglucosamine, which has wide applications in the food and pharmaceutical fields. Fermentation using chitinolytic microorganisms can be used to produce N-acetylglucosamine from shrimp shells’ chitin. One of the strong chitinolytic bacteria that was isolated from previous research was Providencia stuartii. To provide better stability and efficiency in fermentation, P. stuartii cells were immobilized using entrapment method in papaya trunk wood. The aims of this research were to determine the optimum papaya trunk wood size, ratio of papaya trunk wood and growth medium, as well as the optimum fermentation cycle to produce N-acetylglucosamine from P. vannamei shrimp shells using submerged fermentation method. The research used experimental method with treatment of different sizes of papaya trunk wood (1 x 1 x 1 cm3, 1.5 x 1.5 x 1.5 cm3, and 2 x 2 x 2 cm3), different ratio of papaya trunk wood and growth medium (1:10, 1:15 and 1:20), and 4 fermentation cycles. Results showed that papaya trunk wood with size of 1 x 1 x 1 cm3 and ratio (w/v) of 1:10 could immobilize 87.08±2.05% of P. stuartii cells and produce the highest N-acetylglucosamine concentration, which was 238177.78±3153.48 ppm. The highest N-acetylglucosamine production was obtained from first fermentation cycle and decreased over the last three cycles, but still produced high concentration of N-acetylglucosamine. Therefore, it is possible to perform continuous N-acetylglucosamine production from shrimp shells using P. stuartii cells immobilized in papaya trunk wood.

Degradation of Chitin using Chitinase Produced from Molecular Identified Bacteria

Chitin and chitinolytic are beneficial enzymes for their biotechnological applications. Chitinases contribute to the generation of carbon and nitrogen in the ecosystem and can prohibit many fungal ailments that can threaten crop production worldwide. The goal of this work was the production and characterization of chitinase enzymes from bacteria isolated from the western region, Saudi Arabia for biocontrol fungal pathogens. Colloidal chitin from shrimp shells was prepared and used for isolation of chitinolytic bacteria on Mineral chitin agar medium from different sources. The most active isolates were AMM1which was characterized and identified as Alcaligenes aquatilis using 16SrRNA.. In conclusion, purified chitinase was success to produce from Alcaligenes aquatilis for medical uses and biocontrol process.

Structures and functions of carbohydrate-active enzymes of chitinolytic bacteria Paenibacillus sp. str. FPU-7

Chitin and its derivatives have valuable potential applications in various fields that include medicine, agriculture, and food industries. Paenibacillus sp. str. FPU-7 is one of the most potent chitin-degrading bacteria identified. This review introduces the chitin degradation system of P. str. FPU-7. In addition to extracellular chitinases, P. str. FPU-7 uses a unique multi-modular chitinase (ChiW) to hydrolyze chitin to oligosaccharides on the cell surface. Chitin oligosaccharides are converted to N-acetyl-D-glucosamine by β-N-acetylhexosaminidase (PsNagA) in the cytosol. The functions and structures of ChiW and PsNagA are also summarized. The genome sequence of P. str. FPU-7 provides opportunities to acquire novel enzymes. Genome mining has identified a novel alginate lyase, PsAly. The functions and structure of PsAly are reviewed. These findings will inform further improvement of the sustainable conversion of polysaccharides to functional materials.

The Potency of UB Forest Chitinolytic Bacteria to Promote Plant Growth and Inhibit Damping off Disease on Soybean

Damping off disease in soybean plants is caused by the fungal Rhizoctonia solani. The damping off disease causes a yield loss of up to 85-100%. The purpose of this study was determining the ability chitinolytic bacteria consortium of UB Forest's in suppressing damping off disease in vitro and in vivo as well as its potential to stimulate the growth of soybean plants. The research stages included isolation of the pathogenic fungus R. solani and the pathogenicity test. Rejuvenation chitinolytic bacterial isolates of UB Forest, test chitinolytic bacteria antagonist of UB Forest against R. solani fungus, test of Plant Growth Promoting (PGP) activities, synergy test of selected chitinolytic bacterial isolates, in vitro test for the inhibition of chitinase crude extract against R. solani, and inhibition test of chitinolytic bacteria consortium against damping off disease. The selected chitinolytic bacteria were code bacteria UB12, UB19, and UB52 with plant growth promoting activities with inhibition percentage of the pathogen R. solani of 73.9%, 67.4%, and 71.7%. The best chitinolytic bacterial isolates were the genus Bacillus sp. and Pseudomonas sp. The inhibition test of chitinase crude extract showed an inhibition percentage of 25-55%.