A Study on the Antimicrobial Activities of Chitin and Chitosan Extracted from Freshwater Prawn Shells (Macrobrachium Nipponense)

Background: Chitin and its deacetylated derivative, chitosan, are unique biopolymers. Owing to their properties such as biocompatibility, biodegradability, and antimicrobial and antioxidant activities, they have been widely applied in various industries. The aim of the study was to investigate the antimicrobial activities of chitin and chitosan extracted from freshwater prawn shells. Methods: In this research, prawn shell (Macrobrachium nipponense) is used as a source of chitin for the extraction of this valuable biopolymer. The inhibition zone of different concentrations (5, 7.5, and 10 mg/mL) of chitin and chitosan was examined for in vitro antibacterial activity against seven kinds of bacterial strains and two fungi (Aspergillus niger and Candida albicans). Furthermore, minimum inhibitory concentration and minimum lethal concentration were determined. Results: Chitosan had a more inhibitory effect than did chitin. Chitosan demonstrated the maximum inhibitory effect in Vibrio cholerae Ogawa, whereas the lowest value was observed in Escherichia coli (P<0.05). Fungal organisms were revealed to be bacterial pathogens more resistant to the chitin and chitosan that were extracted from prawn shell. Also, chitin and chitosan showed maximum inhibitory effects on A. niger. The lowest minimum inhibitory concentration for chitin and chitosan was between 0.005% and 0.01%, and 0.005% and 0.1%, respectively. Conclusions: Chitosan showed greater antibacterial effect than did chitin against studied bacteria particularly V. Cholerae Ogawa and Staphylococcus aureus and also revealed good antifungal effects. Thus, chitosan may be used as a source of antimicrobial agent for medical and pharmaceutical applications