However, screening of the RDP10 database for oral bacteria with this type of morphology and ≤ 2 sequence mismatches within the gene fragments complementary to these probes, failed to reveal any hints about the possible identity of these

filaments. Experiments aiming at their isolation by fluorescence activated cell sorting are ongoing. Typing of Lactobacillus isolates from in situ grown oral biofilms With the aim to verify the identification by FISH of the lactobacilli present in the three in situ grown biofilm samples (Figure 3), aliquots were cultured on LBS agar. Five strains (OMZ 1117-1121), representing the various colony types observed, were isolated and characterized by both FISH and partial sequencing of the 16S rDNA (Table 3). Sequence analysis identified two strains as L. fermentum (OMZ 1117 and 1121) [EMBL: FR667951] and two as L. casei/L. selleck screening library paracasei (OMZ

ATM/ATR phosphorylation 1118 and 1120) [EMBL: FR667952], based on 100% sequence similarity with respective reference strains. The fifth strain was typed as L. vaginalis (OMZ 1119) [EMBL: FR667953] with a sequence match score of 0.995 17DMAG to reference strain Dox G3. L. vaginalis had not been detected by direct FISH analysis of the biofilms (Figure 3), presumably because the cell number was below the detection limit of approximately 103 bacteria per ml of sample suspension. Tested by FISH with the whole set of probes all five isolates showed the anticipated profile (Table 3). The two L. fermentum Carnitine palmitoyltransferase II isolates were negative to weakly positive with LAB759 in repeated experiments. This is explained by L. fermentum strains having an adenine at position 760 of their 16S rRNA, as opposed to a cytosine at the corresponding position of probe LAB759. This peripheral mismatch may result sometimes in weak cross-reactivity (see also L. fermentum strains in Table 2). In summary, typing by gene sequencing corroborated the data obtained from the direct FISH analysis of the in situ grown biofilms. Table 3 Identification and FISH reactivity profiles of five isolates from in sit u biofilms 013, 051 and 059   Isolated strain (biofilm of origin)   OMZ 1117 (013)

OMZ 1118 (013) OMZ 1119 (051) OMZ 1120 (051) OMZ 1121 (059) 16S rRNA probes           LGC358a 2-4 + 3-4 + 3-4 + 3-4 + 3 + LAB759 + LAB759-comp – to 2 + 3-4 + 3-4 + 3 + – to 2 + Lpla759 – - – - – Lpla990+ H1018 – - – - – L-Lbre466 – - – - – L-Lbuc438 – -a -a -a – Lcas467 – 4 + – 3-4 + – Lsal574 – - – - – L-Lsal1113 – - – - – Lreu986 + H967 2-4 + – 3-4 + – 3-4 + Lfer466 + H448 + H484 2-4 + – - – 3-4 + L-Lcol732 – - – - – Lvag222 – - 3-4 + – - Lgas458 – - – - – Lgas183 – - – - – Identification c L. fermentum L. paracasei L.casei L. vaginalis L. paracasei L.casei L. fermentum a Positive at ≤ 45% formamide. b Scoring of fluorescence intensity is described in a footnote to Table 2. c Species identification was based on ≥ 99.