Characterization of Microbes Present in Purge Pump and Separator Assembly Ground Testing

Microbiology is a growing sector in the field of human spaceflight development. Microorganisms have been observed and studied on crewed missions and space stations. The presence of microbes has potentially detrimental effects on crew health and hardware structure and maintenance. These effects are especially present on flight hardware involved with human wastewater, such as the Water Recovery System (WRS) of the International Space Station (ISS). The Urine Processor Assembly (UPA) of the WRS was recently updated to include the Purge Pump and Separator Assembly (PPSA). The PPSA improves the purge capability and therefore overall performance of the UPA. This paper details microorganisms present within three PPSA pumps after ground testing. Ground microbial testing and decontamination are essential for preventing further system contamination during flight technology demonstrations. The microbial characterization from these pumps includes qualitative and quantitative descriptions of bacterial and fungal species present. DNA sequencing, genome assembly, and identification were performed using Nanopore MinION and KBase. All three sampled pumps showed microbial growth. Bacteria were identified in both the Burkholderia and Ralstonia genera. This work has implications for the viability of urine processor technology against biofouling for longer duration spaceflight missions where hardware replacement is infeasible.