The antibacterial activity of chitin, chitosan and their oligomers
chitosans markedly inhibited
growth of most bacteria tested; however, the inhibitory
effects differed with regard to the molecular
weight of chitosan and the type of bacterium. Chitosan
generally showed stronger bactericidal effects for
gram-positive bacteria than for gram-negative bacteria
in the presence of 0.1% chitosan, as observed by Jeon
et al. (2001). With gram-negative bacteria, chitosan of
746 kDa appeared most effective against E. coli and
P. fluorescens, compared with chitosan (470 kDa)
against S. typhimurium and V. parahaemolyticus.
Chitosan of Mw = 1106 and 224 kDa possessed weak
or no antibacterial activity (Mw = 28 kDa) against S.
typhimurium. In contrast to the response of gramnegative
bacteria, growth of gram-positive bacteria