Chitin exhibited a bacteriostatic effect on Gram-negative
bacteria, E. coli ATCC 25922, V. cholerae, S. disenteriae and
B. fragilis. Chitosan exhibited a bacteriostatic effect on all bacteria
tested, except S. typhimurium. The oligomers exhibited a bactericidal
effect on all bacteria tested. Differences in activity were
exhibited between the type and/or molecular weight of the
chitinous material and the bacterial species. Chito-oligomers would
have advantages as new antimicrobial agents due to their higher
activity and since they are also more readily soluble in water than
the native polysaccharides. On a commercial basis N-acetyl chitooligosaccharides
(NAc-COS) would be preferred since it is
prepared directly from chitin without the need for a deacetylation
step, while chito-oligosaccharides (COS) must be prepared from
chitosan. Both have similar antibacterial activity. Further work is
needed to better understand the mode of action of chitin, chitosan
and its oligomers as antimicrobial agents