05 (Additional file 2, Tables S2-S4). For simplicity, the mostly differentially expressed genes were grouped into functional categories (Figure 2), (i.e., fulfilling the criteria B > 0 by B-test and more than 1.5-fold change), in biofilms formed on hydroxyapatite, titanium Sepantronium mw and composite vs. polystyrene surfaces. Eight selected genes were further analyzed by real time RT-PCR (Figure 3). Criteria for gene selection were either highly up-regulated or highly down-regulated genes, associated with virulence, and of known function rather than hypothetical genes. Among the most regulated ones were
genes associated with stressful environmental conditions andsynthesis of molecular chaperones, in addition to cell wall associated proteins and adhesion-promoting genes. The real-time RT-PCR
analysis confirmed only partially the expression ratios determined by microarray technique. Figure 1 Differentially expressed genes in biofilms formed on different surfaces. Alignments of differentially expressed genes (P < 0.05) of S. mutans biofilms formed on hydroxyapatite, titanuim Ilomastat cell line and composite (vs. polystyrene surfaces), showing the number of overlapping genes between the biofilms on different surfaces. Gene annotations are based on the genome information of S. mutans provided by TIGR. Figure 2 functional categories of most differentially expressed genes. Most significant (B* > 0) differentially expressed genes of S. mutans, grouped in functional categories, in biofilms formed on hydroxyapatite (A), titanium (B) and composite (C) vs. polystyrene surfaces. Gene annotations are based on information provided by TIGR. *Bayesian test value, i.e. the probability for a gene to be really differentially Tolmetin expressed. Figure 3 Expression of selected genes analyzed by RT-PCR. Comparison of RT-PCR expression values for selected genes of S. mutans, grown on different surfaces. SMU.81, SMU.82 (dnaK) and SMU.1954 (groEL) are stress-related
genes; SMU.574c, SMU.609, and SMU.987 are associated with cell wall proteins. SMU.744 codes for FtsY, while SMU.618 codes for a hypothetical protein. The data are expressed as the means of at least two biologically independent experiments. To evaluate the physiological state of the selleckchem immobilized bacterial populations generated on the different tested surfaces, the biofilms were characterized by using CLSM. Biofilm depth analysis showed that the bacteria were able to construct more confluent and profound biofilms on HA surface compared to other tested surfaces (Figure 4). According to the CLSM images, relatively little biofilm growth of about 62-micron depth was observed on the polystyrene surface (Figure 4c), whereas the biofilm formed on the HA surface was notably deeper, up to 173-micron depth (Figure 4b). Moreover, the vitality of the bacteria grown on the HA surface was much greater than those cultured on the polystyrene surface (Figure 4). Figure 4 Biofilms of S.