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The Arctic environments constitute rich and dynamic ecosystems, dominated by microorganisms extremely well adapted to survive and function under severe conditions. A range of physiological adaptations allow the microbiota in these habitats to withstand low temperatures, low water and nutrient availability, high levels of UV radiation, etc. In addition, other adaptations of clear competitive nature are directed at not only surviving but thriving in these environments, by disrupting the metabolism of neighboring cells and affecting intermicrobial communication. Since Arctic microbes are bioindicators which amplify climate alterations in the environment, the Arctic region presents the opportunity to study local microbiota and carry out research about interesting, potentially virulent phenotypes that could be dispersed into other habitats around the globe as a consequence of accelerating climate change. In this context, exploration of Arctic habitats as well as descriptions of the microbes inhabiting them are abundant but microbial competitive strategies commonly associated with virulence and pathogens are rarely reported. In this project, environmental samples from the Arctic region were collected and microorganisms (bacteria and fungi) were isolated. The clinical relevance of these microorganisms was assessed by observing the following virulence markers: ability to grow at a range of temperatures, expression of antimicrobial resistance and production of hemolysins. The aim of this project is to determine the frequency and relevance of these characteristics in an effort to understand microbial adaptations in habitats threatened by climate change. The isolates obtained and described here were able to grow at a range of temperatures, in some cases more than 30 °C higher than their original isolation temperature. A considerable number of them consistently expressed compounds capable of lysing sheep and bovine erythrocytes on blood agar at different incubation temperatures. Ethanolic extracts of these bacteria were able to cause rapid and complete lysis of erythrocyte suspensions and might even be hemolytic when assayed on human blood. In silico analyses showed a variety of resistance elements, some of them novel, against natural and synthetic antimicrobial compounds. In vitro experiments against a number of antimicrobial compounds showed resistance phenotypes belonging to wild-type populations and some non-wild type which clearly denote human influence in the acquisition of antimicrobial resistance. The results of this project demonstrate the presence of virulence-associated factors expressed by microorganisms of natural, non-clinical environments. This study contains some of the first reports, to the best of our knowledge, of hemolytic microbes isolated from the Arctic region. In addition, it provides additional information about the presence and expression of intrinsic and acquired antimicrobial resistance in environmental isolates, contributing to the understanding of the evolution of relevant pathogenic species and opportunistic pathogens. Finally, this study highlights some of the potential risks associated with changes in the polar regions (habitat melting and destruction, ecosystem transition and re-colonization) as important indirect consequences of global warming and altered climatic conditions around the planet.
Water is essential to life and thus, an essential resource. However, freshwater resources are limited and their maintenance is crucial. Pollution with chemicals and pathogens through urbanization and a growing population impair the quality of freshwater. Furthermore, water can serve as vector for the transmission of pathogens resulting in water-borne illness.
The Interdisciplinary Research Group III – "Water" of the Leibniz alliance project INFECTIONS‘21 investigated water as a hub for pathogens focusing on Clostridioides difficile and avian influenza A viruses that may be shed into the water. Another aim of this study was to characterize the bacterial communities in a wastewater treatment plant (WWTP) of the capital Berlin, Germany to further assess potential health risks associated with wastewater management practices.
Bacterial communities of WWTP inflow and effluent differed significantly. The proportion of fecal/enteric bacteria was relatively low and OTUs related to potential enteric pathogens were largely removed from inflow to effluent. However, a health risk might exist as an increased relative abundance of potential pathogenic Legionella spp. such as L. lytica was observed. Three Clostridioides difficile isolates from wastewater inflow and an urban bathing lake in Berlin (‗Weisser See‘) were obtained and sequenced. The two isolates from the wastewater did not carry toxin genes, whereas the isolate from the lake was positive for the toxin genes. All three isolates were closely related to human strains. This indicates a potential, but rather sporadic health risk. Avian influenza A viruses were detected in 38.8% of sediment samples by PCR, but virus isolation failed. An experiment with inoculated freshwater and sediment samples showed that virus isolation from sediment requires relatively high virus concentrations and worked much better in Madin-Darby Canine Kidney (MDCK) cell cultures than in embryonated chicken eggs, but low titre of influenza contamination in freshwater samples was sufficient to recover virus.
In conclusion, this work revealed potential health risks coming from bacterial groups with pathogenic potential such as Legionella spp. whose relative abundance is higher in the released effluent than in the inflow of the investigated WWTP. It further indicates that water bodies such as wastewater and lake sediments can serve as reservoir and vector, even for non-typical water-borne or water-transmitted pathogens such as C. difficile.