P Y2
Antimicrobial Activity of Different Chitosan Fractions
Against Spoilage Microorganisms in Seafood
Tri Erny Dyahningtyas, Benward Bisping
University of Hamburg, Hamburg, Germany
The antimicrobial activity of different chitosan-fractions has been evaluated by testing against
four different spoilage microorganisms in seafood. The chitosan-fractions were differing in
viscosities, degrees of deacetylation (DD) and molecular masses (Mη). The antimicrobial
activities of chitosan-fractions were determined against two gram-negative bacteria
(Escherichia coli and Salmonella typhimurium) and two gram-positive bacteria
(Staphylococcus aureus, and Listeria monocytogenes) in 0.1% solution. The activities of
chitosan-fractions were compared by determining the MIC (Minimum Inhibitory Concentration)
of each fraction in a range from 0.003% to 0.1% in 1% acetic acid. The results indicate that
chitosan-fractions with low viscosity, low Mη and high DD showed a stronger antimicrobial
activity against the four spoilage microorganisms in seafood. It was also observed that
chitosan-fractions showed a higher antimicrobial effect against gram-positive bacteria than
against gram-negative bacteria. The exact mechanism of the antimicrobial action of chitosan
& their derivates is still unknown, but the above result devise a hypothesis that the
mechanism of chitosan antibacterial action involves a cross-linkage between the polycations
of chitosan and anions on the bacterial surface that changes the membrane permeability.