1, Table 1). Clones of bovine strains did not cluster together with clones of human strains, indicating that these clones are habitat
related (Fig. 1, Table 1). Comparison of Hungarian bovine strains with international human counterparts resulted CT99021 only four overlapping clones mostly related to CF (Fig. 1, Table 1). On the other hand, several of our bovine strains could be integrated within environmental clonal complexes (B, E71, S42) described very recently in Germany (Selezska et al., 2012), indicating the possibility of natural interchange between environmental and bovine strains (Fig. 1, Table 1). Diverging clonality of the bovine and human strains was confirmed by cluster analysis taking into account all 20 genetic markers of the core genome, including SNPs, as well as di- and multiallelic loci fliC and fpvA (Fig. 2). At a similarity cutoff of 50%, five major genetic clusters (A–E) could be distinguished, and they tended to be represented by the strains from one or the other habitat. Accordingly, 18 of the 24 human strains were grouped into one large cluster (A), whereas 20 of 24 bovine strains were grouped into three large clusters B, D, and E (Fig. 2). As further essential components of the CP-690550 nmr core genome, the genes of pyoverdine receptors FpvA were also analyzed. Pyoverdines are primary siderophores
and signal molecules for virulence factors of P. aeruginosa. Different types of FpvA receptor proteins serving for iron uptake are alternatively encoded in the genome. Considering the above differences
found in core genomes, it was logical to assume that bovine, human and environmental strains may also differ regarding their FpvA receptor types. Results of PCR microarray typing of pyoverdine receptor genes indicated that human strains were characterized by the overrepresentation (75%) of type I FpvA receptor genes (Fig. 3) which is in harmony with previous finding of Wiehlmann et al. (2007). The predominance of type I FpvA gene (52.2%) was also found among the environmental strains. In contrast, bovine strains have been characterized by the relative dominance (45.8%) of type III FpvA (Fig. 3). Statistical analysis (chi-square test with Yates correction) confirmed that Thiamine-diphosphate kinase the above overrepresentation of type III FpvA receptors among bovine strains relative to the human (12.5%) and environmental strains (8.7%) is significant (P < 0.05), and it was not related to the place (farm) of isolation. Thus, the clonal separation of bovine strains from human and environmental strains was also manifested in the differences of their FpvA receptor types. It seems that this finding is a novel contribution to earlier studies where the comparative genetic characterization of P. aeruginosa strains from humans, from diverse animal sources, and from the environment revealed no significant correlation between the habitat and the FpvA receptor gene types (Pirnay et al.