Characterization of four Escherichia albertii isolates collected from animals living in Antarctica and Patagonia.

Escherichia albertii is a recently discovered species with a limited number of well characterized strains. The aim of this study was to characterize four of the E. albertii strains, which were among 41 identified Escherichia strains isolated from the feces of living animals on James Ross Island, Antarctica, and Isla Magdalena, Patagonia. Sequencing of 16S rDNA, automated ribotyping, and rep-PCR were used to identify the four E. albertii isolates. Phylogenetic analyses based on multi-locus sequence typing showed these isolates to be genetically most similar to the members of E. albertii phylogroup G3. These isolates encoded several virulence factors including those, which are characteristic of E. albertii (cytolethal distending toxin and intimin) as well as bacteriocin determinants that typically have a very low prevalence in E. coli strains (D, E7). Moreover, E. albertii protein extracts caused cell cycle arrest in human cell line A375, probably because of cytolethal distending toxin activity.

Human Escherichia coli strains of different geographical and time source: bacteriocin types and their gene sequences are population-specific.

Bacteriocin production was tested in two sets of Escherichia coli strains: one isolated in 1978 from healthy children of rubber tree tappers and Indians in Amazonia, Brazil (n = 35), and the second one isolated in 2004 from healthy adult volunteers in the Moravia region, Czech Republic (n = 53). Although the occurrence of bacteriocin production was rather similar in both groups (54.3% and 43.4% respectively), the spectra of bacteriocin-encoding determinants in both groups were different. Altogether, 12 different bacteriocin-encoding determinants were found among the tested strains. The occurrence of colicin E1- and Y-genes was higher (P = 0.02 and P = 0.009 respectively) while the occurrence of microcin V gene was lower (P = 0.02) among Amazonian strains compared with Moravian strains. The colicin-encoding determinants of colicins Ia, M, Y and E1 were amplified from Amazonian and Moravian producer strains and sequenced, as were chromosomal 16S rRNA, gyrB and tonB genes. While sequence alignments of chromosomal loci revealed no clusters with respect to geographical origin of strains, the colicin-encoding genes were very similar among the strains of each origin but different between the two geographic groups.