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Structural characterization and antimicrobial activity of chitosan (CS-40)/nisin complexes

Authors

  • Jun Cai,

    Corresponding author
    1. Key Laboratory of Fermentation Engineering (Minister of Education), Hubei Provincial Key Laboratory of Industrial Microbiology, College of Bioengineering, Hubei University of Technology, Wuhan 430068, China
    • Key Laboratory of Fermentation Engineering (Minister of Education), Hubei Provincial Key Laboratory of Industrial Microbiology, College of Bioengineering, Hubei University of Technology, Wuhan 430068, China
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  • Jianhong Yang,

    1. Department of Environmental Science, College of Resource and Environmental Science, Wuhan University, Wuhan 430079, Hubei, China
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  • Changgao Wang,

    1. Key Laboratory of Fermentation Engineering (Minister of Education), Hubei Provincial Key Laboratory of Industrial Microbiology, College of Bioengineering, Hubei University of Technology, Wuhan 430068, China
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  • Ying Hu,

    1. Key Laboratory of Fermentation Engineering (Minister of Education), Hubei Provincial Key Laboratory of Industrial Microbiology, College of Bioengineering, Hubei University of Technology, Wuhan 430068, China
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  • Jianguo Lin,

    1. Key Laboratory of Fermentation Engineering (Minister of Education), Hubei Provincial Key Laboratory of Industrial Microbiology, College of Bioengineering, Hubei University of Technology, Wuhan 430068, China
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  • Lihong Fan

    1. College of Chemical Engineering, Wuhan University of Technology, Wuhan 430070, Hubei, China
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Abstract

A complex of chitosan (CS-40) and nisin (CS-40/nisin) was prepared and characterized with Fourier transform infrared spectroscopy and thermal analysis (thermogravimetry, differential thermogravimetry, and differential scanning calorimetry). The results show that the complex formed mainly by electrostatic interaction between the protonated amino group in CS-40 backbone with the carboxylate ion of nisin. Minimum inhibitory concentrations (MICs) were evaluated against Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, and Bacillus stearothermophilus), Gram-negative bacteria (Escherichia coli, Salmonella enteritidis, and Proteus vulgaris), and fungi (Fusarium oxysporum). The results show that the CS-40/nisin solution did inhibit or even more strongly inhibited the growth of all the tested microorganisms, whereas CS-40 did not inhibit the growth of F. oxysporum and nisin did not inhibit the growth of Gram-negative bacteria (E. coli, S. enteritidis, and P. vulgaris). The relative inhibition times of CS-40/nisin solutions with different concentrations and ratios of CS-40 and nisin were also investigated against the seven microorganisms. The results showed that CS-40/nisin solutions with CS-40/nisin concentration ratios of 0.05/0.005, 0.05/0.0025, 0.05/0.00125, and 0.025/0.0001% had higher antimicrobial activity against all tested bacteria and fungi. The relationship between complex formation and antimicrobial activity is discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

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