A simultaneous permeabilization of the cell
membrane to small cellular components was detected coupled to
a significant membrane depolarization. Furthermore, chitosan
treatment of S. simulans 22 cells did not give rise to cell wall lysis
with the cell membrane remaining intact. Analysis of transcriptional
response data of S. aureus SG511 revealed that chitosan
treatment leads to changes in gene expression related to regulation
of stress, autolysis and energy metabolism. Raafet et al.
(2008) went on to speculate that a possible mechanism for chitosan’s
activity consists of binding of the biopolymer to teichoic
acids (i.e. polysaccharides found within the cell wall of Grampositive
bacteria), coupled with extraction of membrane lipids
that results in a sequence of events that eventually lead to
bacterial death. A good review of chitosan as an antimicrobial
agent with applications and mode of action is provided by