Chitin and Chitosan from Crustacean Shell Waste: Extraction and Antibacterial Activity Against Fish Pathogens

Marine crustaceans such as shrimps, lobsters, and crabs constitute a major part of seafood options around the world. The crustacean shell waste is a cause of environmental concern due to the growing demand and accumulation in the environment. In this study, chitin and chitosan were extracted from the shells of three crustaceans such shrimp, lobster and crab using chemical extraction method. The extracted materials were tested for their antimicrobial activity against the fish pathogenic bacteria Streptococcus agalactiae to find the potential applications in aquaculture. Results indicated the significantly (p < 0.05) higher chitin yield of about 21% (dry weight) from shrimp shells than crab (15.96%) and lobster shells (17.16%). FT-IR analysis confirmed chitinous structures such as amide 1 (around 1600 cm−1), amide II (around 1500 cm−1), and polysaccharide bands C-O (around 1200 cm−1) in both chitin and chitosan extracted from the three crustacean species. Chitin and chitosan also inhibited the growth of fish pathogen S. agalactiae with a maximum zone of inhibition of 23 mM. Overall, this study showed that crustacean shell waste contained a higher percentage of chitin that can be used as valuable product while minimizing the environmental pollution.