Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Mora,M.
Microbes in restricted indoor environments - with focus on the International Space Station and spacecraft associated clean rooms
PhD-Studium (Doctor of Philosophy); Humanmedizin; [ Dissertation ] Graz Medical University; 2019. pp. 148
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- Autor*innen der Med Uni Graz:
- Betreuer*innen:
- Moissl-Eichinger Christine
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- Abstract:
- This work investigated the microbiome of two distinct restricted indoor environments: The Internationals Space Station (ISS) and spacecraft associated clean rooms (SACR) on Earth. The ISS is inhabited by the human crew and co-inhabiting microorganisms and is characterized by a variety of unique environmental features, such as microgravity and a higher background radiation than most Earth environments. SACR are highly particulate controlled built environments. Both environments have in common that they are anthropogenic and are challenging for microbial life due to rigorous cleaning protocols, mechanical ventilation with highly efficient particulate air filters, and a low nutrient availability and water activity. At the timepoint of sampling (2014-2017), the investigated SACR housed cargo transporters destined towards the ISS. ISS samples comprised wipe samples obtained during increments 51 and 52 (2017) and dust samples retrieved during ISS expedition 9 (2004) and 16 (2008). Samples from both environments were analyzed by microbial amplicon sequencing, cultivation, comparative physiological studies, and antibiotic resistance tests. ISS microbial isolates were additionally investigated via genome analysis and co-incubation experiments with ISS-relevant materials. These analyses were conducted with the goal to elucidate following questions: I) Can Archaea and extremophilic (or extremotolerant) microorganisms be cultivated and/or detected on board the ISS? II) Do microbes adapt to a life in space on board the ISS and if yes to which extent? III) Are Isolates from the ISS more resistant than respective ground control strains according to physiologic tests and are observed resistances reflected in the genomes of selected isolates? IV) Does the ISS indoor microbiome differ over time or in different locations within the ISS? V) Is the ISS microbial diversity (dis)similar from that in SACRs If and if yes to what extent? VI) Are ISS isolates obtained in this study able to form biofilms on ISS relevant material and/or are they able to degrade or corrode these materials? It was possible to assess the detectable as well as the cultivable microbial diversity on board the ISS, including Archaea and a variety of extremophilic/tolerant Bacteria, and to identify a core diversity which was found to be stable over years. The ISS microbial diversity was, however, only to a minor extent influenced by SACR microbes. While the ISS environment was found to select for microbial survival and adaption specialists, these hardy microbes were not found to be significantly more or less resistant with regard to ISS environmental factors than related microbes from terrestrial environments with regard to their limits of growth or their genomic content. ISS isolates did partly show a strong antibiotics-resistance potential, however, also here we could not observe a difference to respective terrestrial strain. Furthermore, some ISS isolates were observed to adhere to ISS-relevant materials, although it remained unclear to what extent these microbes were able to damage these materials. The data obtained in this work indicates no reason for concern with respect to crew health, but indicates a potential threat towards biofilm formation and material integrity in moist areas. This thesis expanded the available knowledge of the ISS indoor microbiome with regard to the presence of Archaea and extremophilic and extremotolerant microbes on board the ISS and provided a baseline of isolates, including a variety of isolates which have not been cultured from the ISS environment before, as well as sequencing data providing information regarding the spatial distribution and temporal succession of the ISS indoor microbiome. These results will contribute to the development of a safe microbial management plan for future long-term space missions and other confined indoor environments on Earth.