Probes were used at final concentrations of 5 ng μ l-1 (Cy3 conjugates) or 15 ng μ l-1 (FAM conjugates, competitor and helper probes). EUB338 served as positive control. FISH was performed as described [30] using hybridization times of 2 or 4 h and probe-specific formamide concentrations as listed in Table 1. Optimum formamide PI3K Inhibitor Library concentrations were determined by varying the formamide concentrations systematically between 25% and 55% in FISH experiments with both reference strains and oral biofilm samples. Scoring and enumeration of stained bacteria Following FISH, air-dried multiwell slides were covered with mounting fluid (90% glycerol in PBS with 25 mg g-1 1,4-diazabicyclo[2, 2, 2]octan)

and cover-slips. Bacteria stained by FISH were enumerated as described using an Olympus BX60 epifluorescence microscope (Olympus Optical [Schweiz]) [30]. Scoring of fluorescence intensity is described in a footnote to Table 2. 16S rDNA sequencing Partial 16S rRNA gene sequences of five lactobacillus isolates (OMZ 1117-1121) from the three in situ grown biofilms were determined as described previously [35]. The sequences of 1393, 1360, 1366, 1371 and 1379 bp in length were compared to gene bank data of the The Ribosomal

Data Base Project using the Seq Match algorithm [33]. Identification of isolates was based on ≥ 99.5% similarity. The sequences of OMZ 1117 – 1119 were deposited at EMBL with accession numbers FR667951 – FR667953. Acknowledgements The authors are grateful to Siren Hammer Østvold for excellent

assistance with the in situ study carried out in Bergen, Norway. This work was supported in Daporinad clinical trial part by the University of Zürich and the Swedish Patent Revenue Fund for Research in Preventive Odontology. References 1. Aas JA, Paster BJ, Stokes LN, Olsen I, Dewhirst FE: Defining the normal bacterial flora of the oral cavity. J Clin Microbiol 2005, 43: 5721–5732.PubMedCrossRef 2. Kilian M: Streptococcus and Lactobacillus . In Topley and Wilson’s Microbiology and Microbial Infections. ALK inhibitor Edited by: Borriello P, Murray PR, Funke G. London: SPTLC1 Hodder Arnold; 2005:833–881. 3. Marsh PD, Martin MV: Oral Microbiology. 5th edition. Edinburgh: Churchill Livingstone Elsevier; 2009. 4. Marsh PD, Nyvad B: The oral microflora and biofilms on teeth. In Dental Caries: The Disease and Its Clinical Management. 2nd edition. Edited by: Fejerskov O, Kidd E. Chichester. UK: Wiley-Blackwell; 2008:163–187. 5. Baddour LM: Virulence factors among gram-positive bacteria in experimental endocarditis. Infect Immun 1994, 62: 2143–2148.PubMed 6. Husni RN, Gordon SM, Washington JA, Longworth DL: Lactobacillus bacterimia and endocarditis: Review of 45 cases. Clin Infect Dis 1997, 25: 1048–1055.PubMedCrossRef 7. Amann R, Fuchs BM: Single-cell identification in microbial communities by improved fluorescence in situ hybridization techniques. Nat Rev Micro 2008, 6: 339–348.CrossRef 8.