Effect of Gamma Irradiation on Antibacterial Properties of Sea Crab Shell Chitosan

Effect of gamma irradiation on antibacterial activities of chitosan is described. Chitosan was prepared from crab shells via demineralization, deproteinization, decoloration and deacetylation. Chitosan solutions (2%) were prepared in 1% acetic acid and irradiated at 0, 5, 15 and 25 kGy. The degree of deacetylation and viscosity-average molecular weight of the chitosan were determined. Susceptibility tests of E. coli and S. parathyphi against the chitosan were determined. E. coli was more susceptible to lower concentrations of chitosan solutions. Irradiated chitosan in solutions exerted a slightly faster inhibition on both E. coli and S. parathyphi than the unirradiated chitosan solution, but there was no difference observed between irradiated and unirradiated chitosan in solutions after 48 hours of incubation. The degree of susceptibility of both E. coli and S. parathyphi to irradiated chitosan in solutions was not significantly affected by the irradiation dose.