Scientific Publications - Work Done by Microbiology Reader Bioscreen C

K.W. KIM, R.L. Thomas, C. Lee, K.T. Hwang, X.G. Chen, H.J. Park, and Y.T. Kim, Antimicrobial activitivity of native, degraded chitosan and carboxymethylated chitosan, IFT - Institute of Food Technologists, 2002 Annual Meeting - Anaheim, California, Session 29, Carbohydrate, 2:30 PM - 4:35 PM, Sunday, June 16

ABSTRACT

O-CM-chitosan is thought to play an important role in the antimicrobial activity of chitosan because it is the substitution of chitosan with CH2COOH only to -OH; its number of -NH2 is not changed. We have identified the antimicrobial activity of native chitosan (MW: 120 kDa, DDA: 95%), degraded chitosan and O-CM-chitosans against E.coli, Staphylococus aureus, Bacillus subtilis and Salmonella typhimunum. The objective of this study was to determine the antimicrobial activity of chitosan by its MW, concentration in solution and substitution to O-CM chitosans with native chitosan and degraded chitosan. Lipase from Rhizopus japonicus degraded 120 kDa chitosan resulting in soluble chitosan hydrolysates of average MW 30 - 50 kDa as shown by size exclusion chromatography. The chitosan degradation products were fractionated according to their MW by ultrafiltration. O-carboxymethylated chitosan with native chitosan (O-CM-chitosan A) and degraded chitosan (O-CM-chitosan B) were produced and characterized by FTIR. The antibacterial activity against four strains of bacteria were explored by MW, concentration in solution and substitution to O-CM chitosans using Bioscreen C. Optimal temperature for the hydrolysis of chitosan was 40C. The fractions exhibited MW of 50, 41, 35 and 30 kDa, respectively. All fractions showed high solubility at neutral pH. The antimicrobacterial activity of native chitosan is excellent than that of degraded chitosan. The significant growth inhibitions for E.coli and Staphylococus aureus were observed even at low concentration. Chitosan effect was not so much sensitive for Bacillus subtilis and Salmonella typhimunum at low concentration. The ODs of O-CM-chitosan B were much lower than that of O-CM-chitosan A except E.coli. O-CM-chitosan A did not show better antimicrobial activity than native chitosan while O-CM-chitosan B showed better antimicrobial activity than degraded chitosan in general. The native chitosan, degraded chitosan and O-CM-chitosans showed the different sensitivity against E.coli, Staphylococus aureus, Bacillus subtilis and Salmonella typhimunum.

(Abstract online)

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