Virulence and drug resistance of Burkholderia and Ralstonia species isolated from International Space Station potable water systems
Authors: Khieu Kristine , Cohen Shirli , Thai Victoria , Anderson Sydney , Lee Henry , O'Rourke Aubrie 
Published: June 2021

The prevalence of microbes living within us and in our environment has been demonstrated by the Human Microbiome Project and the Sloan Foundation funded MoBE (Microbiome of the Built Environment) research. A prime example of an extreme human‐built environment is the International Space Station (ISS). Studying the ISS in the context of MoBE illustrates the behavior of microbial life in space. High levels of radiation and microgravity exposure can alter human physiology and microbiology. Maintaining human health becomes synonymous with monitoring bacteria in extreme environments. For instance, the ISS potable water system has been found to be susceptible to growth of certain bacterial strains. These include Burkholderia multivorans, Burkholderia cepacia, genomovars of the B. cepacia complex (BCC), an unclassified species of Burkholderia, and its relatives Ralstonia pickettii and Ralstonia insidiosa. Members of these genera can survive long periods in a planktonic state in distilled water or as biofilms within an infected individual. While the presence of these strains may not harm healthy people, it may affect immunocompromised astronauts living closely together for long duration missions.

This study characterizes the ISS isolates in relation to terrestrial controls through genomic sequencing and phenotypic assessment. Genomic sequencing of the isolates has identified genetic markers associated with resistance, virulence, and pathogenicity. Phenotypic testing determined their propensity to form biofilms, resist antibiotic treatment, and inhibit unicellular and multicellular eukaryotic organisms.

65 potable water system isolates were sequenced, de novo assembled, and bioinformatically compared to all existing strains for the respective species represented in the National Center for Biotechnology Information repository (NCBI). The core genome, represented in all strains of space‐adapted and terrestrial species, and the auxiliary genomes of the space‐adapted strains were identified. Antibiotic resistance or tolerance were also analyzed by determining the minimal inhibitory concentration (MIC) for each of the 65 bacterial isolates against clinically relevant antibiotics. Additionally, the isolates were co‐cultured with the diatom Phaeodactylum tricornutum and the fungus Aspergillus fumigatus to assess their ability to inhibit growth in comparison to a terrestrial control strain. Finally, the formation of biofilms on different metals was analyzed to compare strains and to provide recommendations for materials that will inhibit bacterial growth in the ISS potable water system.

The results of these studies provide information on the genotypic and phenotypic changes present in a space adapted population and how these differences, compared to a terrestrial control, present the potential for altered virulence and pathogenicity.

Support or Funding Information

J. Craig Venter Institute with Post‐Doctoral funding support from NASA. Solicitation: NNH16ZTT001N‐MOBE.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.