Endemic and Cosmopolitan Bacteria From Microbial Mats in Maritime Antarctica: Antagonism and Antibiotic Resistance

The expansion of species alien to the polar environment interferes with stable microbiocenotic systems and adversely affects endemic prokaryotic populations. This is the first study to demonstrate a relationship between antagonistic interactions and antibiotic resistance among bacterial species with different biogeographical ranges, found in freshwater microbial mats in King George Island, Maritime Antarctica. In the current study, taxonomic structure, antibiotic resistance and antagonistic interactions of 47 isolates of bacteria originating from Antarctic freshwater microbial mats were examined. Bacterial isolates were classified into two groups with different ecogeographic ranges: endemic species occurring only in permanently cold, frozen and/or periodically frozen ecosystems and cosmopolitan species, common in natural environments and adapted to diverse environmental conditions. Strains of cosmopolitan species compared to endemic species were characterised by broad antagonism and resistance to antibiotics. The individual patterns of antagonistic interactions and antibiotic resistance observed among isolates showed a clear relationship with the biogeographical ranges of individual species. Bacterial communities of Antarctic freshwater microbial mats are vulnerable to the expansion of bacterial species with global ranges. Cosmopolitan strains as a specific 'biological contaminants' may be the source and propagator of new traits in endemic populations of polar mat microbiocenoses.