Background and purpose: Chitin is one of the main components of crustaceans’ exoskeleton. Chitosan is produced by deacetylation of chitin. Molecular weight and degree of deacetylation play important roles in biological activity of chitin, chitosan, and their derivatives. So far, various derivatives of chitin and chitosan are obtained. The purpose of this study was to prepare derivatives of chitin and chitosan derived from the shells of shrimp (Metapenaeus affinis) to compare their antibacterial properties.
Materials and methods: By investigating different factors, the best condition was determined for extracting chitin and chitosan from the shell of Metapenaeus affinis. N-acetyl chitooligosaccharides and chitooligosaccharides oligomers were prepared through chemical hydrolysis of chitin and chitosan, respectively. The antimicrobial properties of four polymers obtained were investigated on four bacterial strains and compared with an emphasis on molecular weight and percentage of deacetylation
Results: The amounts of ash, moisture, protein, and molecular weight of chitin was found to be more than those of chitosan. But, the degree of deacetylation of chitosan was much higher than that of chitin. The highest and lowest antibacterial activity was seen in chitooligomers and chitin, respectively. Chitin (somewhat) and chitosan showed bacteriostatic properties against most strains. But, the oligomers revealed bactericidal activity against most of the strains.
Conclusion: This study showed that a product with higher purity can be obtained by manipulating the extraction method (demineralization and deproteinization). Moreover, antibacterial activity is directly related to reduced molecular weight and increased percentage of deacetylation, so, oligomers showed more antibacterial properties.