Antimicrobial activity of chitin, chitosan and their
derivatives against bacteria
Wang [45] observed that a much higher concentration
of chitosan (1±1.5%) is required for complete inactivation
of Staphylococcus aureus after two days of incubation
at pH 5.5 or 6.5 in the medium. Furthermore,
Chang et al. [50] found that chitosan concentrations of
0.005 were sucient to elicit complete inactivation of
S. aureus. This was in accordance with the ®ndings of
Darmadji and Izumimoto [51] on the eect of chitosan
in meat preservation. Simpson et al. [52] studied the
antimicrobial eect of dierent cultures of bacteria on
raw shrimp, with dierent concentrations of chitosan
and observed variations in their degree of susceptibility
to chitosan. According to their ®ndings, Bacillus cereus
required chitosan concentrations of (0.02% for bactericidal
eect, while Escherichia coli and Proteus vulgaris
showed minimal growth at 0.005%, and complete inhibition
at 0.0075%. Chang et al. [50] also reported
inhibition of B. cereus by chitosan. However, much
lower concentrations (0.005%) were required, perhaps
due to the low molecular weight (35 kD) of chitosan
used in their experiment. Numerous studies have also
shown the eect of chitosan on E. coli inhibition. Wang
[45] observed complete inactivation after a 2-day incubation
period with concentrations of 0.5 or 1%, at pH
5.5. He also reported that complete inactivation could
be reached even after ®rst day, if the chitosan concentration
is more than 1% in the broth. Meanwhile,
Darmadji and Izumimoto [51] reported that higher
concentrations (0.1%) were required to inhibit E.coli