Chitosan is polycationic at pH < 6 and interacts readily with negatively charged substances such as proteins, anionic polysac-charides, fatty acids, bile acids and phospho lipids due to the high density of amino groups present on the polymer.Theme chanism of the antimicrobial activity of chitosan and its deriva-tives is unknown. It has been suggested that a positive charge on theNH3+group of the glucosamine monomer at pH < 6.3 allows inter-actions with negatively charged microbial cell membranes whichleads to the leakage of intracellular constituents.Antimicrobial activity of chitosan is higher at low pH; this is dueto the fact that the amino groups of chitosan become ionized at pHbelow 6 [19,92]. In a study by Younes et al.