Abstract
Many Arctic biomes, which are populated with abundant and diverse microbial life, are under threat: climate change and warming temperatures have raised concerns about diversity loss and possible emergence of pathogenic microorganisms. At present, there is little information on the occurrence of Arctic virulence-associated phenotypes. In this study we worked with 118 strains of bacteria (from 10 sampling sites in the Arctic region, located in Greenland and the Svalbard Archipelago) isolated using R2A medium. These strains belong to 4 phyla and represent 36 different bacterial genera. Phenotypic resistance to 8 clinically important antimicrobials (ampicillin, chloramphenicol, ciprofloxacin, cefotaxime, erythromycin, imipenem, kanamycin, and tetracycline) and thermotolerance range were determined. In addition, a screening of all isolates on blood agar media and erythrocytes suspension of bovine and sheep erythrocytes for virulence-linked hemolytic activity was performed. Although antimicrobial resistance profiles varied among the isolates, they were consistent within bacterial families and genera. Interestingly, a high number of isolates (83/104) were resistant to the tested concentration of imipenem (4 mg/L). In addition, one third of the isolates showed hemolytic activity on blood agar, however, in only 5% of the isolates hemolytic activity was also observed in the cell extracts when added to erythrocyte suspensions for 60 min. The observed microbial phenotypes contribute to our understanding of the presence of virulence-associated factors in the Arctic environments, while highlighting the potential risks associated with changes in the polar areas in the light of climate change.
Highlights
The Arctic region, once considered a “biological desert,” is regarded as a rich and dynamic ecosystem (Krajick, 2001; Post et al, 2009), characterized by diverse biomes that harbor species from all three domains of life (Anesio and Laybourn-Parry, 2012)
In the present study of bacterial isolates from the Arctic region, we investigated three phenotypes commonly associated with pathogenic bacteria, i.e., growth at 37◦C, the hemolytic activity on blood agar plates at different temperatures as well as on erythrocyte suspensions and resistance to 8 different, commonly used and clinically relevant antimicrobials
Due to its low adaptability, these consequences are amplified (Doney et al, 2012) and the stressful conditions they bring about might cause the release of environmental bacteria with potential virulence-associated phenotypes, e.g., compounds with hemolytic activity and antimicrobial resistance
Summary
The Arctic region, once considered a “biological desert,” is regarded as a rich and dynamic ecosystem (Krajick, 2001; Post et al, 2009), characterized by diverse biomes that harbor species from all three domains of life (Anesio and Laybourn-Parry, 2012). While every environment on Earth is influenced, Arctic environments are affected and, their average temperatures have increased almost twice as fast as the global warming rate in the past 100 years (Intergovernmental Panel on Climate Change [IPCC], 2007). Despite the fact that climate change directly affects microorganisms, microbial life is rarely studied in this context (Cavicchioli et al, 2019). When their interactions with other species are perturbed, the resulting pressures strongly influence microbial community composition and function and might play a role in the expression of bacterial virulence factors (Livermore, 2003). Altered climatic conditions might enable virulent and/or antimicrobial resistant microbes, originating from temperate regions, to reach previously pristine and unperturbed Arctic environments, spreading virulence factors and resistance genes (Altizer et al, 2013)
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