Chitosan oligomers (Table 2) also inhibited bacterial
growth by 1– 5 log cycles at a 1.0% concentration;
however, effects were more limited than those of the
chitosans. With gram-negative bacteria, antibacterial
activity seemed to increase with decreasing Mw;
however, this trend was not observed with grampositive
bacteria. In general, chitosan oligomers of 1
kDa showed relatively greater antimicrobial activity
against gram-negative bacteria while chitosan oligomers
of 4 and 2 kDa against gram-positive bacteria
compared with other Mws.