In-Line Microbial Monitor for the Analysis of Recycled Water Aboard the ISS: Issues and Prospects

The monitoring of spacecraft life support systems for the presence of health threatening microorganisms is paramount for crew well being and successful completion of missions. The union of the molecular biology techniques of DNA probe hybridization and polymerase chain reaction (PCR) offers a powerful method for the detection, identification, and quantification of microorganisms and viruses. This report is an evaluation of the state of PCR science as it applies to the needs of NASA to develop a microbiology monitor for use aboard spacecraft, and a set of recommendations as to the design of a PCR-based microbial monitor for recycled water aboard the ISS. Issues pertinent to the development of a PCR-based microbial monitor for reclaimed water on the ISS are discussed including: (1) instrumentation and chemistry for quantitative PCR, (2) the inability of PCR to distinguish between viable and non-viable microorganisms, (3) possible PCR inhibitors in ISS water, (4) methods of pre-PCR sample concentration and preparation, (5) what microorganisms need to be monitored, and (6) development of the DNA probes a PCR-based monitor would need to identify potentially dangerous microbial contaminants.