The Selleckchem BIIB057 conserved core genes make up 80% of all genes included in this study. Hence, 20% (374) of all genes of W83 were aberrant in at least one of the strains.

Core genomes from several bacterial species have been described [39–45]. The fraction of a bacterial genome that consists of core genes depends highly on the amount of strains included to describe the core genome [43]. The more strains are used, the smaller the core genome will be. As such, the very well studied Escherichia coli core genome makes up only 46% of the average E. coli genome. Other bacterial species, including Gram positives and Gram negatives, have been found to have a core genome which covers 52% to 85% of a genome [39–45]. The 80% of W83

genes which are buy KU-57788 part of the conserved core genome can therefore be understood. It must be clear though that the core genome of P. gingivalis as described here must be seen as a first step. The core genome will be found to be smaller as more genetic information on different P. gingivalis strains will become available. We could distinguish two gene sets in the aberrant set, namely the present and absent genes (Figure 2). Using aberrance and absent call analysis we were thus able to describe the P. gingivalis core genome in two ways. Aberrance represents mutations within the probe sequence, whereas absent calls represents the total selleck chemical absence of the probe sequence interpreted as gene absence. The fully conserved P. gingivalis core genome is comprised of 1476 genes. The variable core genome is comprised of a total of 1605 genes, which are aberrant, but called present (Figure 2). In the further analyses the conserved core genome was CYTH4 taken as the core genome. Figure 2 P. gingivalis core genome. Pie diagram representing all probes included in the results divided into pieces representing the conserved core genome, aberrant core genome and the

variable genes. The percentages show the proportions of the total of functional probes. 80% of the strain W83 genes is present and conserved among the test strains. 6% of the W83 genes is present but aberrant and 13% of the genes is absent in at least one of the test strains. Two probes with very low signals were found as non-aberrant but absent. Combining our findings on the core genome with a study describing 1490 conserved CDSs when comparing the genome sequences of W83 and ATCC33277 [28], makes it tempting to speculate that the core genome as described here may already be close to its final size. An analysis combining the conserved CDSs from that study with our 1476 conserved core genes showed that when strain ATCC33277 is included the core genome size decreased to 1384 genes. The conserved core gene set was analyzed for the presence of virulence genes.