Chitosan disrupts the barrier properties of the outer membrane of Gram-negative bacteria

Ilkka Helander, E.-L. Nurmiaho-Lassila, Raija Ahvenainen, J. Rhoades, S. Roller (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

The mode of antimicrobial action of chitosan (polymeric β-1,4-N-acetylglucosamine) on Gram-negative bacteria was studied with special emphasis on its ability to bind to and weaken the barrier function of the outer membrane (OM). Chitosan (250 ppm) at pH 5.3 induced significant uptake of the hydrophobic probe 1-N-phenylnaphthylamine (NPN) in Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium. The effect was reduced (E. coli, salmonellae) or abolished (P. aeruginosa) by MgCl2. No NPN uptake was observed during exposure of the salmonellae to chitosan at pH 7.2. Chitosan also sensitized P. aeruginosa and the salmonellae to the lytic effect of sodium dodecyl sulfate (SDS); such sensitization was not blocked by MgCl2 and was reversible by washing chitosan-treated cells prior to SDS exposure. Chemical and electrophoretic analyses of cell-free supernatants of chitosan-treated cell suspensions showed that interaction of chitosan with E. coli and the salmonellae involved no release of lipopolysaccharide (LPS) or other membrane lipids. However, chitosan rendered E. coli more sensitive to the inhibitory action of dyes and bile acids used in selective media. Highly cationic mutants of S. typhimurium were more resistant to chitosan than the parent strains. Electron microscopy showed that chitosan caused extensive cell surface alterations and covered the OM with vesicular structures. Chitosan thus appeared to bind to the outer membrane, explaining the loss of the barrier function. This property makes chitosan a potentially useful indirect antimicrobial for food protection.
Original languageEnglish
Pages (from-to)235-244
Number of pages10
JournalInternational Journal of Food Microbiology
Volume71
Issue number2-3
DOIs
Publication statusPublished - 2001
MoE publication typeA1 Journal article-refereed

Fingerprint

Chitosan
chitosan
Gram-Negative Bacteria
Gram-negative bacteria
Membranes
Salmonella
Pseudomonas aeruginosa
Escherichia coli
Magnesium Chloride
N-phenyl-1-naphthylamine
sodium dodecyl sulfate
Salmonella typhimurium
Salmonella Typhimurium
Sodium Dodecyl Sulfate
anti-infective agents
uptake mechanisms
N-acetylglucosamine
Acetylglucosamine
selective media
bile acids

Keywords

  • chitosan
  • antibacterial
  • food preservative
  • preservatives
  • outer membrane
  • gram-negative bacteria
  • chitin

Cite this

Helander, Ilkka ; Nurmiaho-Lassila, E.-L. ; Ahvenainen, Raija ; Rhoades, J. ; Roller, S. / Chitosan disrupts the barrier properties of the outer membrane of Gram-negative bacteria. In: International Journal of Food Microbiology. 2001 ; Vol. 71, No. 2-3. pp. 235-244.
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Helander, I, Nurmiaho-Lassila, E-L, Ahvenainen, R, Rhoades, J & Roller, S 2001, 'Chitosan disrupts the barrier properties of the outer membrane of Gram-negative bacteria', International Journal of Food Microbiology, vol. 71, no. 2-3, pp. 235-244. https://doi.org/10.1016/S0168-1605(01)00609-2

Chitosan disrupts the barrier properties of the outer membrane of Gram-negative bacteria. / Helander, Ilkka; Nurmiaho-Lassila, E.-L.; Ahvenainen, Raija; Rhoades, J.; Roller, S. (Corresponding Author).

In: International Journal of Food Microbiology, Vol. 71, No. 2-3, 2001, p. 235-244.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Chitosan disrupts the barrier properties of the outer membrane of Gram-negative bacteria

AU - Helander, Ilkka

AU - Nurmiaho-Lassila, E.-L.

AU - Ahvenainen, Raija

AU - Rhoades, J.

AU - Roller, S.

PY - 2001

Y1 - 2001

N2 - The mode of antimicrobial action of chitosan (polymeric β-1,4-N-acetylglucosamine) on Gram-negative bacteria was studied with special emphasis on its ability to bind to and weaken the barrier function of the outer membrane (OM). Chitosan (250 ppm) at pH 5.3 induced significant uptake of the hydrophobic probe 1-N-phenylnaphthylamine (NPN) in Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium. The effect was reduced (E. coli, salmonellae) or abolished (P. aeruginosa) by MgCl2. No NPN uptake was observed during exposure of the salmonellae to chitosan at pH 7.2. Chitosan also sensitized P. aeruginosa and the salmonellae to the lytic effect of sodium dodecyl sulfate (SDS); such sensitization was not blocked by MgCl2 and was reversible by washing chitosan-treated cells prior to SDS exposure. Chemical and electrophoretic analyses of cell-free supernatants of chitosan-treated cell suspensions showed that interaction of chitosan with E. coli and the salmonellae involved no release of lipopolysaccharide (LPS) or other membrane lipids. However, chitosan rendered E. coli more sensitive to the inhibitory action of dyes and bile acids used in selective media. Highly cationic mutants of S. typhimurium were more resistant to chitosan than the parent strains. Electron microscopy showed that chitosan caused extensive cell surface alterations and covered the OM with vesicular structures. Chitosan thus appeared to bind to the outer membrane, explaining the loss of the barrier function. This property makes chitosan a potentially useful indirect antimicrobial for food protection.

AB - The mode of antimicrobial action of chitosan (polymeric β-1,4-N-acetylglucosamine) on Gram-negative bacteria was studied with special emphasis on its ability to bind to and weaken the barrier function of the outer membrane (OM). Chitosan (250 ppm) at pH 5.3 induced significant uptake of the hydrophobic probe 1-N-phenylnaphthylamine (NPN) in Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium. The effect was reduced (E. coli, salmonellae) or abolished (P. aeruginosa) by MgCl2. No NPN uptake was observed during exposure of the salmonellae to chitosan at pH 7.2. Chitosan also sensitized P. aeruginosa and the salmonellae to the lytic effect of sodium dodecyl sulfate (SDS); such sensitization was not blocked by MgCl2 and was reversible by washing chitosan-treated cells prior to SDS exposure. Chemical and electrophoretic analyses of cell-free supernatants of chitosan-treated cell suspensions showed that interaction of chitosan with E. coli and the salmonellae involved no release of lipopolysaccharide (LPS) or other membrane lipids. However, chitosan rendered E. coli more sensitive to the inhibitory action of dyes and bile acids used in selective media. Highly cationic mutants of S. typhimurium were more resistant to chitosan than the parent strains. Electron microscopy showed that chitosan caused extensive cell surface alterations and covered the OM with vesicular structures. Chitosan thus appeared to bind to the outer membrane, explaining the loss of the barrier function. This property makes chitosan a potentially useful indirect antimicrobial for food protection.

KW - chitosan

KW - antibacterial

KW - food preservative

KW - preservatives

KW - outer membrane

KW - gram-negative bacteria

KW - chitin

U2 - 10.1016/S0168-1605(01)00609-2

DO - 10.1016/S0168-1605(01)00609-2

M3 - Article

VL - 71

SP - 235

EP - 244

JO - International Journal of Food Microbiology

JF - International Journal of Food Microbiology

SN - 0168-1605

IS - 2-3

ER -