The increase in the DD implies that
an increased number of protonated amino groups are present
on chitosan [10] below its pKa (pH 6.3) which interact with
the negatively charged cell walls of micro-organisms. For the
same reason, the antimicrobial activity of chitosan is strongly
affected by the pH, showing an enhanced antibacterial action
at lower pH [11]. Chitosan has several advantages over other
well known antibacterial agents due to its demonstrated low
cytotoxicity [12].