Songklanakarin Journal of Science and Technology (SJST) (Jan 2008)
Effect of deacetylation conditions on antimicrobial activity of chitosans prepared from carapace of black tiger shrimp (Penaeus monodon)
Abstract
Chitosan was prepared from black tiger shrimp carapace by deacetylation process performed in 50% NaOH at 100oC under vacuum, nitrogen and regular atmospheres. Each condition was maintained for 0.5, 1.0 and 2.0 h. Chitosan obtained from 1.0 h of deacetylation under regular atmosphere showed the lowest minimum inhibitory concentration (MIC) value of 625 ppm against Escherichia coli and Staphylococcus aureus, while Candida albicans was inhibited at MIC value of 312.5 ppm due to its higher degree of deacetylation (% DD) and lower molecular weight (MW) compared to chitosan deacetylated under vacuum and nitrogen atmospheres. Chitosan hydrolysates obtained from both chemical (H2O2 in the presence of ferricions) and enzymatic (lysozyme) hydrolysis were not as inhibitory as the native one, except that from chemical hydrolysis, which showed the elevation of the antifungal activity against C. albicans when longer hydrolysis was performed. However, antibacterial activity against E. coli decreased when the MW of hydrolyzed chitosan decreased.
