Microbial isolation and characterization from two flex lines from the urine processor assembly onboard the...

Area of Science:

• Space microbiology
• Water recovery systems
• Biofilm formation

Background:

• The International Space Station (ISS) Water Recovery System (WRS) processes non-potable water into potable water.
• Routine microbial monitoring is challenging in many WRS components.
• Two flex lines from the Urine Processor Assembly (UPA) were returned to Earth for analysis.

Purpose of the Study:

• To microbiologically evaluate water and flush water from ISS UPA flex lines.
• To identify microbial communities, including bacteria and fungi, within these lines.
• To investigate biofilm formation and genomic characteristics of isolated microorganisms.

Main Methods:

• Culture-based and culture-independent microbial analyses.
• Hybrid de novo genome analysis of bacterial isolates.
• Environmental scanning electron microscopy (ESEM) for biofilm imaging.
• Phenotypic assays for biofilm potential, bacterial-fungal interactions, and hemolytic activity.

Main Results:

• Identification of Burkholderia, Paraburkholderia, Leifsonia, Fusarium, and Lecythophora.
• Genomic identification of isolates as B. contaminans and P. fungorum, with unique chromate-resistance gene clusters.
• First evidence of fungal-bacterial biofilms within ISS UPA flex lines.
• B. contaminans demonstrated significant biofilm formation and possessed gene clusters for quorum sensing, biofilm formation, and antifungal compounds.

Conclusions:

• UPA flex lines represent a unique ecological niche for microbial growth and biofilm development within the WRS.
• The identified microbial populations possess distinct genomic features, including resistance genes.
• Understanding these organisms and their resistance is crucial for developing engineering controls to prevent biofilm formation in future space water systems.