CONICET | Buscador de Institutos y Recursos Humanos

pDCPR1 and pDL209 plasmids belong to a new incompatibility group, ColE2-like, which has the particularity ofhaving an hybrid structure composed by genes with homology to the replicase (repA) of Pseudomonas savastanoi, andto partition genes (parA and parB) from Xanthomonas albilineans. Both species are pathogens of somecommercially important plants. In this work, we investigated the distribution of this new incompatibility group in clinical and environmental strains from Argentina in order to determine the presumable direction of the gene flow. PCRs were performed using specific primers for repA, parA and parB in DNA extractions with DNAPuriprep-GP Kit (Inbio Highway) of 88 strains isolated between 2004-2014belonging to genera Pseudomonas, Serratia, Escherichia, Citrobacter,Enterobacter, Proteus, Salmonella, Klebsiella and Yersinia from hospitals (n=76) and environment (n=12). In addition,repA and parA trees were constructed using Neighbour Joining of allaccession numbers with up to 60% identity at the protein level (n= 65 for repA, n= 34 for parA). Fifteen repA positive amplifications wereobtained. These corresponded to the genus Pseudomonas including P.putida, P. fluorescens and P.mendocina, as well as P. aeruginosa,and Serratia marcescens (n = 1). The26,67% of repA positive strains alsopossessed parA, although 3,41% of thetotal isolates had only parA or parB gene. We identified a higherfrequency of genes associated with this incompatibility group (repA, parA and parB) in ?interface? species than in the other strains.Regarding the repA gene, we observed adaptations todifferent niches either plants, clinical and environmental niches, including increasedhost range plasmids. At the same time, we noted a differential spread of plasmidsbetween the two hemispheres, with two trends: dissemination in P. syringae in the northern hemisphere,and horizontal genetic transfers in the southern hemisphere. With respect to parA, we observed two clusters disseminatingboth in several ecological niches and species.Our results showed at an epidemiological levelthe hybrid feature of ColE2-like replicons. These results indicated awide distribution of components of this replicon particularly in Pseudomonas spp. strains, which,although isolated in the clinic, they are usually found in the open environmentsuch as P. putida, P. fluorescens and P. mendocina. The fact thatsome of these genes are mostly found in environmental strains would demonstratethat clinical settings select those mobile elements from different habitatswhich confer adaptive advantages for successful dispersion of pathogenicstrains. This view supports the presence of a bidirectional flow betweenenvironment and clinic, to which a transitional step or ?interface? at aspecies level is added, exemplified by environmental strains isolated in theclinic, that could act as reservoirs and vectors.