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Influence of electric fields and pH on biofilm structure as related to the bioelectric effect

Influence of electric fields and pH on biofilm structure as related to the bioelectric effect
Influence of electric fields and pH on biofilm structure as related to the bioelectric effect
Mixed species biofilms of Klebsiella pneumoniae, Pseudomonas fluorescens, and Pseudomonas aeruginosa were grown in a flow cell fitted with two platinum wire electrodes. The biofilm growing on the wires reached a thickness of approximately 50 microm after 3 days. When a voltage was applied with oscillating polarity, the biofilm attached to the wire expanded and contracted. The biofilm expanded by approximately 4% when the wire was cathodic but was reduced to 74% of the original thickness when the wire was anodic. The phenomenon was reproduced by alternately flushing the flow cell with media adjusted to pH 3 and pH 10 with no electric current. At pH 10 the biofilm was unaltered, but it became compacted to 69% of the original thickness at pH 3. We explained these phenomena in terms of the molecular interactions between charged acidic groups in the biofilm slime and the bacterial cell walls. Contraction of the biofilm under acidic conditions may be caused by (i) the elimination of electrostatic repulsion from neutralization of negatively charged carboxylate groups through protonation and (ii) subsequent hydrogen bonding between the carboxylic acids and oxygen atoms in the sugars. Electrostatic interactions between negatively charged groups in the biofilm and the charged wire may also be expected to cause biofilm expansion when the wire was cathodic and contraction when the wire was anodic. The consequences of the explanation of the increased susceptibility of biofilm cells to antibiotics in an electric field, the "bioelectric effect," are discussed.
0066-4804
1876-1879
Stoodley, P.
08614665-92a9-4466-806e-20c6daeb483f
deBeer, D.
78a5fcaa-e0f4-413b-83b9-97f7281b3055
Lappin-Scott, H.M.
fa1948ea-97cd-47a8-9fea-4f67567a50c8
Stoodley, P.
08614665-92a9-4466-806e-20c6daeb483f
deBeer, D.
78a5fcaa-e0f4-413b-83b9-97f7281b3055
Lappin-Scott, H.M.
fa1948ea-97cd-47a8-9fea-4f67567a50c8

Stoodley, P., deBeer, D. and Lappin-Scott, H.M. (1997) Influence of electric fields and pH on biofilm structure as related to the bioelectric effect. Antimicrobial Agents and Chemotherapy, 41 (9), 1876-1879.

Record type: Article

Abstract

Mixed species biofilms of Klebsiella pneumoniae, Pseudomonas fluorescens, and Pseudomonas aeruginosa were grown in a flow cell fitted with two platinum wire electrodes. The biofilm growing on the wires reached a thickness of approximately 50 microm after 3 days. When a voltage was applied with oscillating polarity, the biofilm attached to the wire expanded and contracted. The biofilm expanded by approximately 4% when the wire was cathodic but was reduced to 74% of the original thickness when the wire was anodic. The phenomenon was reproduced by alternately flushing the flow cell with media adjusted to pH 3 and pH 10 with no electric current. At pH 10 the biofilm was unaltered, but it became compacted to 69% of the original thickness at pH 3. We explained these phenomena in terms of the molecular interactions between charged acidic groups in the biofilm slime and the bacterial cell walls. Contraction of the biofilm under acidic conditions may be caused by (i) the elimination of electrostatic repulsion from neutralization of negatively charged carboxylate groups through protonation and (ii) subsequent hydrogen bonding between the carboxylic acids and oxygen atoms in the sugars. Electrostatic interactions between negatively charged groups in the biofilm and the charged wire may also be expected to cause biofilm expansion when the wire was cathodic and contraction when the wire was anodic. The consequences of the explanation of the increased susceptibility of biofilm cells to antibiotics in an electric field, the "bioelectric effect," are discussed.

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More information

Published date: September 1997
Additional Information: Selected for Journal Highlights ASM News
Organisations: Engineering Mats & Surface Engineerg Gp

Identifiers

Local EPrints ID: 157465
URI: http://eprints.soton.ac.uk/id/eprint/157465
ISSN: 0066-4804
PURE UUID: 1ddd63a0-9ce4-4367-9de9-23fe29a717b6
ORCID for P. Stoodley: ORCID iD orcid.org/0000-0001-6069-273X

Catalogue record

Date deposited: 15 Jun 2010 14:26
Last modified: 09 Jan 2022 03:32

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Contributors

Author: P. Stoodley ORCID iD
Author: D. deBeer
Author: H.M. Lappin-Scott

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