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The Internal Active Thermal Control System (IATCS) aboard the International Space Station (ISS) contains an aqueous, alkaline fluid (pH 9.5±0.5) that aids in maintaining a habitable environment for the crew. Because microbes have significant potential to cause disease, adverse effects on astronaut health, and microbe-induced corrosion, the presence of both bacteria and viruses within IATCS fluids is of concern. This study sought to detect and identify viral populations in IATCS samples obtained from the Kennedy Space Center as a first step towards characterizing and understanding potential risks associated with them. Samples were concentrated and viral nucleic acids (NA) extracted providing solutions containing 8.87-22.67 μg NA per mL of heat transfer fluid. After further amplification viral DNA and cDNA were then pooled, fluorescently labeled, and hybridized onto a Combimatrix panvira 12K microarray containing probes for ∼1,000 known human viruses.

Certain Eubacteria enter a viable but nonculturable (VBNC) state upon encountering unfavorable environmental conditions. VBNC cells do not divide on conventional media yet remain viable and in some cases retain virulence. Here, we describe the VBNC state of two opportunistic pathogens previously isolated from ISS potable waters, Burkholderia cepacia and Stenotrophomonas maltophilia. Artificially inoculated microcosms were exposed to the biocidal agents copper (CuSO4) and iodine (I2) in an attempt to induce nonculturablility. Viability was assessed via fluorescent microscopy (direct viable count assay coupled with BacLight™ staining) and metabolic activity was monitored by quantifying both intracellular ATP and transcribed rRNA (reverse transcriptase quantitative PCR). Culturablility was lost in both B. cepacia and S. maltophilia within two days of exposure to copper or high concentrations of iodine (6 or 8 ppm).