Abstract:

Effect of chitosan from redswamp crayfish on bacterial cell surface was investigated. Escherichia coli (E.coli) and Staphylococcus aureus (S.aureus) were treated with chitosan solutions at varying concentrations for 3.5 h. The leakage of celluar content, the asparate transaminase (AST) activity, total protein (TP) content and nucleic acid content in the supernatants of bacterial suspension treated with the chitosan solutios were analyzed as well as morphological alterations of bacteria using transmission electron microscope (TEM). Results indicated that AST activity and the contents of TP nuleotides in chitosan solutions were significant higher than those in control (p < 0.01). TEM image indicated the cellular content leakage and morphological alterations of both bacteria treated with chitosan. Chitosan was also found to significantly enhance SDS-induced bacteriolysis (p < 0.01). Our results suggested that chitosan from redswamp crayfish is able to damage the bacterial surface structure and lead to the loss of barrier function and the leakage of cellular content.

Key words: chitosan, redswamp crayfish, bacterial cell surface, Escherichia coli, Staphylococcus aureus