Antibacterial activity of chitin, chitosan and its oligomers prepared from shrimp shell waste

The antimicrobial activities of chito-oligosaccharides against four Gram-positive and seven Gram-negative bacteria were compared to chitosan and chitin with an emphasis on the effects of biopolymer molecular weight (Mv) and degree of deacetylation (DD). Chitin was isolated from shrimp ( Parapenaeus longirostris ) shell waste by sequential chemical treatments. Chitosan and its oligomers N-acetyl chito-oligosaccharides and chito-oligosaccharides were prepared by deacetylation and chemical hydrolysis, respectively. Chitin exhibited a bacteriostatic effect on Gram-negative bacteria, Escherichia coli ATCC 25922, Vibrio cholerae , Shigella dysenteriae , and Bacteroides fragilis . Chitosan exhibited a bacteriostatic effect on all bacteria tested, except Salmonella typhimurium . The oligomers exhibited a bactericidal effect on all bacteria tested. ► Chitin and chitosan were prepared from shrimp shells. ► Antibacterial activity of chitin and chitosan oligomers were assessed. ► Chitosan exhibited a bacteriostatic effect on all bacteria tested. ► Due to their higher activity, oligomers were more soluble in water. ► Chito-oligomers showed advantages as new antimicrobial agents.