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Antibacterial activity of chitosans with different degrees of deacetylation and viscosities

Jung, Eun Ju, Youn, Dal Kyoung, Lee, Shin Ho, No, Hong Kyoon, Ha, Jong Gill, Prinyawiwatkul, Witoon
International journal of food science & technology 2010 v.45 no.4 pp. 676-682
Bacillus cereus, Bacillus subtilis, Escherichia coli, Gram-positive bacteria, Lactobacillus curvatus, Listeria monocytogenes, Pectobacterium carotovorum, Proteus vulgaris, Pseudomonas fluorescens, Salmonella Typhimurium, Serratia marcescens, Staphylococcus aureus, Vibrio parahaemolyticus, antibacterial properties, chitosan, microbial growth, minimum inhibitory concentration, viscosity
Antibacterial activities of six acid-soluble [two degrees of deacetylation (DD) x three viscosities] and two water-soluble chitosans (two DD with similar viscosities) were examined against eight gram-negative (Pseudomonas fluorescens, Proteus vulgaris, Erwinia carotovora, Serratia marcescens, Escherichia coli, Vibrio parahaemolyticus, V. vulnificus, and Salmonella Typhimurium) and six gram-positive bacteria (Listeria monocytogenes, Staphylococcus aureus, Bacillus subtilis, B. cereus, Lactobacillus curvatus, and L. plantarum). Antibacterial activities of chitosans differed depending on the chitosan types and bacteria tested. Water-soluble chitosans inhibited bacterial growth by one to eight log cycles at 0.1% concentration; however, the effects were much lesser than those observed with 0.05% acid-soluble chitosans. Minimum inhibitory concentration (MIC) values (0.03% to above 0.1%) of acid-soluble chitosans were much lower than those (0.05% to above 0.8%) of water-soluble chitosans. Based on MIC values, the acid-soluble chitosan with 99% DD and lower viscosity (17.9 mPa s) was most effective in inhibiting bacteria growth among eight chitosans tested.