NATL1A and Prochlorococcus marinus str. NATL2A (PG producing organisms), Ruminococcus torques L2-4 (PG producing organism), the node joining of Dehalococcoides organisms (PG-less organisms), the node before Ternericutes and the node joining the Verrucomicrobia, Chlamydia

and Planctomycetes phyla (Figure 1). The only one GT51 gene gain event was observed for Akkermansia muciniphila ATCC BAA 835 (Figure 1) (PG producing organism). Figure 3 A 16S rDNA sequence phylogenetic tree-like representation. This representation features Bacteria phyla comprising organisms with a GT51 gene (black), phyla including some close representatives without a GT51 gene selleck chemicals llc (green), phyla including isolated representatives without a GT51 gene (blue) and phyla for which all representatives lack ITF2357 chemical structure a GT51 gene (red). Figure 4 Phylogenic 16S rDNA gene-based tree extracted from a 1,114 sequence tree from IODA. GT51 gene loss events are presented by a red square. The gain/loss phylogenetic trees are available on the IODA website [15]. The multivariable analysis of life style, genome size, GC content and absence or presence

of PG indicated that a GC content <50%, genome size <1.5 Mb and an obligate intracellular life style were significantly correlated with the absence of PG, with odds ratios of 7.7, 80 and 19.5 and confidence intervals of 3–15.5, 42.4-152.4 and 11.7-32.5, respectively (P<10-3). Examples of such GT51-negative, PG-less obligate intracellular Bacteria include Chlamydia[16], Anaplasma, Ehrlichia, Neorickettsia and Orientia[17, 18]. Discussion In this study, mining the CAZy database allowed the detection of a minimal set of three genes involved in PG synthesis among the four different domains of life. The fact that this complete 3-gene set was not detected in Archaea and Viruses organisms is in agreement with the previously known absence of PG in these organisms and validated

our method [19]. In Archae, family GT28 genes are only very distantly related to the bona Cyclic nucleotide phosphodiesterase fide bacterial GTs involved in PG synthesis, and it is possible that the archaeal GT28 enzymes have a function unrelated to PG. In viruses, detecting a few genes potentially involved in the synthesis and in the degradation of PG was not surprising: such viruses were indeed bacterial phages in which GH genes could have recombined with the bacterial host genome [20, 21] and could be used to break through the peptidoglycan layer to penetrate their bacterial hosts. More surprising was the observation that the Eukaryote Micromonas sp. encodes a complete 3-gene set. Micromonas sp. is a photosynthetic picoplanktonic green alga containing chloroplasts (Figure 5) [22]. A significant association was observed between photosynthetic Eukaryotes and the presence of genes involved in PG metabolism. Chloroplasts are thought to descend from photosynthetic Cyanobacteria ancestors, and their presence in photosynthetic Eukaryotes is thought to result from Eukaryotes-Cyanobacteria symbiosis [23].