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molecular oral microbiology

Killing of anaerobic pathogens by predatory bacteria
M. Van Essche1, M. Quirynen1, I. Sliepen1, G. Loozen1, N. Boon2, J. Van Eldere3 and W. Teughels1
1 Department of Periodontology, Catholic University Leuven, Leuven, Belgium 2 LabMET, Laboratory of Microbial Ecology & Technology, Ghent University, Gent, Belgium 3 Centre for Molecular Diagnostics, CatholicUniversity Leuven, Leuven, Belgium Correspondence: Wim Teughels, Department of Periodontology, Catholic University Leuven, Kapucijnenvoer 7, 3000, Leuven, Belgium Tel.: +32 16 332505; fax: +32 16 332484; E-mail: Wim.Teughels@med.kuleuven.be Keywords: periodontitis; bdellovibrio; predatory Accepted 20 September 2010 DOI: 10.1111/j.2041-1014.2010.00595.x

SUMMARY Recently, the predation of Bdellovibriobacteriovorus on a periodontal pathogen has been described. The current study explores the potential antimicrobial activity of a range of predatory bacteria against key periodontal pathogens. A number of representatives from the Bdellovibrio, Bacteriovorax and Peredibacter lineages (called ‘BALOs’) were tested for their activity towards a group of key periodontal pathogens and an optimalmultiplicity of infection was established. As the oral cavity contains a wide variety of bacteria that are not preyed upon, it was investigated if they can have an effect on the predation efficiency of BALOs. It was concluded that a number of important variables involved in bacterial predation are found to be compatible with the composition of the oral microbiota. This finding makes the case for continuedstudy of the potential for BALOs to combat periodontal pathogens. ces (Schwudke et al., 2001). These minute assassins have a peculiar lifestyle: they swim around at high speed and after collision with a susceptible prey bacterium, they attach to their prey and enter its periplasm. The invaded prey is subsequently converted into a hybrid structure of predator–prey called the ‘bdelloplast’. Theconversion from an uninvaded prey cell into a bdelloplast often coincides with a morphological change to a spherical structure although this is not always the case and initial prey morphology can be maintained throughout most of ´˜ the predation process (Nunez et al., 2003). This bdelloplast supports the development of the predator until its multiplication is completed. At that point, the bdelloplast isruptured and the offspring of the initial attack-phase cell is released into the environment (Varon & Shilo, 1968; Lambert et al., 2006). In spite of this remarkable behaviour, BALOs have only been sparsely investigated. Advances in molecular techniques have demonstrated that the presence of BALOs in the environment is considerably underestimated (Van Essche et al., 2009b) although they aregenerally not isolated from the environment in large numbers (Mahmoud et al., 2007). These findings suggest that the effect of bacterial predation on microbial communities might be much more extensive than previously assumed. Periodontitis is a polymicrobial infection involving numerous gramnegative pathogens embedded in a complex biofilm
Molecular Oral Microbiology 26 (2011) 52–61 ª 2010 John Wiley &Sons A/S

INTRODUCTION Bdellovibrio-and-like organisms (BALOs) are a diverse group of highly motile deltaproteobacteria that are obligatory predators of gram-negative bacteria (Stolp & Starr, 1963). They are ubiquitous in terrestrial and aquatic environments (Jurkevitch et al., 2000) and have also been isolated from human fae52

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Bacterial predation on anaerobic pathogenscalled dental plaque (Pihlstrom et al., 2005). From a microbiological point of view, the treatment of periodontal diseases is complicated by a number of drawbacks. First, the application of antimicrobials is discouraged in light of the growing resistance to antibiotics (van Winkelhoff et al., 2005). Second, antimicrobials are ineffective in penetrating bacterial biofilms such as dental...