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Real time microsensor measurement of local metabolic activities in ex vivo dental biofilms treated with chlorhexidine

Real time microsensor measurement of local metabolic activities in ex vivo dental biofilms treated with chlorhexidine
Real time microsensor measurement of local metabolic activities in ex vivo dental biofilms treated with chlorhexidine
Dental biofilms are characterized by structural and functional heterogeneity. Due to bacterial metabolism, gradients develop and diverse ecological microniches exist. The aims of this study were (i) to determine the metabolic activity of microorganisms in naturally grown dental biofilms ex vivo by measuring dissolved oxygen (DO) and pH profiles with microelectrodes with high spatial resolution and (ii) to analyze the impact of an antimicrobial chlorhexidine (CHX) treatment on microbial physiology during stimulation by sucrose in real time. Biofilms were cultivated on standardized human enamel surfaces in vivo. DO and pH profiles were measured in a flow cell system in sterile human saliva, after sucrose addition (10%), again after alternative treatment of the sucrose exposed biofilms with CHX (0.2%) for 1 or 10 min or after being killed with paraformaldehyde (4%). Biofilm structure was visualized by vitality staining with confocal microscopy. With saliva as the sole nutrient source oxygen consumption was high within the superficial biofilm layers rendering deeper layers (>220 mum) anoxic. Sucrose addition induced the thickness of the anaerobic zone to increase with a concurrent decrease in pH (7.1 to 4.4). CHX exposure reduced metabolic activity and microbial viability at the biofilm surface and drove metabolic activity deeper into the biofilm. CHX treatment led to a reduced viability at the biofilm surface with minor influence on overall biofilm physiology after 1 min; even after 10 min there was measurable respiration and fermentation inside the biofilm. However, the local microenvironment was more aerated, less acidogenic, and presumably less pathogenic.

0099-2240
2326-2334
Von Ohle, C.
68242015-ba57-4102-a368-2a3509be8785
Gieseke, A.
9e64f3c8-aced-493d-8efc-e9868dcb04d0
Nistico, L.
11f06ab1-8a7b-4957-be24-1c0027b5bd64
Decker, E.M.
3a3cfc08-ecc5-45ec-b0d5-9086e6f29369
DeBeer, D.
78a5fcaa-e0f4-413b-83b9-97f7281b3055
Stoodley, P.
08614665-92a9-4466-806e-20c6daeb483f
Von Ohle, C.
68242015-ba57-4102-a368-2a3509be8785
Gieseke, A.
9e64f3c8-aced-493d-8efc-e9868dcb04d0
Nistico, L.
11f06ab1-8a7b-4957-be24-1c0027b5bd64
Decker, E.M.
3a3cfc08-ecc5-45ec-b0d5-9086e6f29369
DeBeer, D.
78a5fcaa-e0f4-413b-83b9-97f7281b3055
Stoodley, P.
08614665-92a9-4466-806e-20c6daeb483f

Von Ohle, C., Gieseke, A., Nistico, L., Decker, E.M., DeBeer, D. and Stoodley, P. (2010) Real time microsensor measurement of local metabolic activities in ex vivo dental biofilms treated with chlorhexidine. Applied and Environmental Microbiology, 76 (7), 2326-2334. (doi:10.1128/AEM.02090-09).

Record type: Article

Abstract

Dental biofilms are characterized by structural and functional heterogeneity. Due to bacterial metabolism, gradients develop and diverse ecological microniches exist. The aims of this study were (i) to determine the metabolic activity of microorganisms in naturally grown dental biofilms ex vivo by measuring dissolved oxygen (DO) and pH profiles with microelectrodes with high spatial resolution and (ii) to analyze the impact of an antimicrobial chlorhexidine (CHX) treatment on microbial physiology during stimulation by sucrose in real time. Biofilms were cultivated on standardized human enamel surfaces in vivo. DO and pH profiles were measured in a flow cell system in sterile human saliva, after sucrose addition (10%), again after alternative treatment of the sucrose exposed biofilms with CHX (0.2%) for 1 or 10 min or after being killed with paraformaldehyde (4%). Biofilm structure was visualized by vitality staining with confocal microscopy. With saliva as the sole nutrient source oxygen consumption was high within the superficial biofilm layers rendering deeper layers (>220 mum) anoxic. Sucrose addition induced the thickness of the anaerobic zone to increase with a concurrent decrease in pH (7.1 to 4.4). CHX exposure reduced metabolic activity and microbial viability at the biofilm surface and drove metabolic activity deeper into the biofilm. CHX treatment led to a reduced viability at the biofilm surface with minor influence on overall biofilm physiology after 1 min; even after 10 min there was measurable respiration and fermentation inside the biofilm. However, the local microenvironment was more aerated, less acidogenic, and presumably less pathogenic.

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More information

Published date: 2010
Additional Information: The National Centre for Advanced Tribology at Southampton (nCATS)
Organisations: Engineering Mats & Surface Engineerg Gp

Identifiers

Local EPrints ID: 71663
URI: http://eprints.soton.ac.uk/id/eprint/71663
ISSN: 0099-2240
PURE UUID: 1e8bd262-2ba7-4b10-ae5b-549f8e591b4e
ORCID for P. Stoodley: ORCID iD orcid.org/0000-0001-6069-273X

Catalogue record

Date deposited: 17 Dec 2009
Last modified: 14 Mar 2024 02:55

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Contributors

Author: C. Von Ohle
Author: A. Gieseke
Author: L. Nistico
Author: E.M. Decker
Author: D. DeBeer
Author: P. Stoodley ORCID iD

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