However, once again 0.1% (w/v) NAc-COS
and COS showed higher antibacterial activities than native polysaccharides
and markedly inhibited the growth of all the tested
bacteria. Almost all V. cholerae and B. fragilis were destroyed after
1.5 h and 2 h of incubation, respectively, in the presence of 0.1% (w/
v) chito-oligomers in the culture medium. Although, the required
time for killing all S. disenteriaewas 1.5 h and 2.5 h for COS and NAc-
COS respectively, suggesting that COS is a more effective antimicrobial
agent.