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Bacterial endospores are ubiquitous in terrestrial environments as a result of their ability to persist through environmental extremes of moisture, chemical toxins, pressure, heat and UV radiation. Current studies suggest that Airborne Endospore Bioburden (AEB) may be used as an indicator of spacecraft cleanliness. AEB, as measured in closed environment air sampling under laboratory conditions and in the Environmental Control and Life Support System at Marshall Space Flight Center, has indicated that increased total counts of airborne endospores can be correlated to surface microbial contamination. Advanced detection methods using PDMS sampling techniques, the highly sensitive terbium-dipicolinic acid (Tb3+-DPA) endospore assay, and standard microbial monitoring methods can be used to track trends in the settling of airborne spores.

A disinfectant-resistant biofilm in a spacecraft potable water system can threaten system maintainability (microbially influenced corrosion/degradation) and crew health (pathogen survival). Iodine, while an effective disinfectant in low doses (ca. 2-4 mg/l) in bulk water, has been demonstrated to have limited effectiveness in controlling mixed aquatic biofilm in both bench-scale and large water reclamation tests. This report provides data on the feasibility of using ozone as an alternative or supplemental disinfectant. Tests were conducted in a biofilm testbed, a 20 liter bench-scale closed-loop recycling water system previously used for iodine disinfection studies. Ozone generated by ultraviolet irradiation of either air or pure oxygen was tested as a disinfectant on an iodine resistant biofilm. The results demonstrate that ozone is an effective disinfectant against an iodine resistant biofilm.