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

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).


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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.

Item Type: Article
Digital Object Identifier (DOI): doi:10.1128/AEM.02090-09
Additional Information: The National Centre for Advanced Tribology at Southampton (nCATS)
ISSNs: 0099-2240 (print)
Subjects: Q Science > Q Science (General)
R Medicine > RK Dentistry
Divisions : University Structure - Pre August 2011 > School of Engineering Sciences > Engineering Materials & Surface Engineering
ePrint ID: 71663
Accepted Date and Publication Date:
Date Deposited: 17 Dec 2009
Last Modified: 31 Mar 2016 13:03

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