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NASA-Marshall Space Flight Center (MSFC) has an interest in an automated in-line monitor that can detect the presence of microbial contamination in recovered water. Ideally, this system should also be able to identify and enumerate the microbial contaminant. The Viable Microbial Monitor (VM2) is based on conductance microbiology which depends on the well documented ability of microorganisms to change the electrochemical properties of their growth medium during incubation. The VM2 is intended for the rapid detection of bacterial or fungal contamination in water and other samples. From October 1992 to July 1993, NASA-MSFC sponsored a Microbial In-line Monitor (MIM) study to evaluate the VM2 for its ability to detect ten microorganism species (9 bacteria and 1 yeast) recovered from Water Recovery Tests (WRT) conducted at MSFC. These WRT isolates may represent the microbes that have potential to contaminate a water recovery system.

Early detection of microbial contaminants in reclaimed water was investigated using conductivity measurements of cultured samples. Culture data were obtained by using conductivity electronics and a personal computer equipped with an analog-digital converter and multiplexer. The software was programmed to monitor 54 cultures. The cultures were incubated for up to 48 hours at 35°C. The real-time conductivity data obtained from these cultured samples produces curves comprised of multiple data points over time. Using laboratory cultures for conductivity measurements, growth was detected within 12-24 hours with inocula in the range of less than 100 to 105 colony forming units per ml (CFU/ml). Detection times ranged from 20-35 hours for reclaimed water samples, and bacteria in untreated waste-waters were detected in 2-15 hours.

Microbial monitoring by instrumental methods will become more necessary as manned spaceflight missions increase in length. Permanently manned space station or lunar bases have potential for microbial problems that we cannot foresee until we begin to monitor activities of organisms in each unique environment. These microbial communities could impair crew health, equipment performance, life science experiments and environmental control systems. The environmental factors that influence each organism's ability to survive, grow, and reproduce on earth can have new influences in variable or reduced gravity. The combination of environmental factors has the potential to produce changed interactions in the microbial communities. Different species may dominate, adapt, or regress in ways we cannot predict from today's information. Microbial instrumentation is being developed for in-situ study and eventual online control monitoring in spaceflight applications.

In Space Station Freedom, the water supply will be a closed loop system. Humidity condensate from the cabin and waste hygiene water including urine are to be reclaimed for potable and hygiene uses. Close monitoring of the water quality is mandatory to ensure crew health. The 30-year utilization planned for SS Freedom requires careful planning for water processing and monitoring systems. Perkin-Elmer is developing a Water Quality Monitor (WQM) for the Environmental Control and Life Support System (ECLSS) being developed by the Boeing Aerospace & Electronics Company.* The WQM will monitor impurities in both potable and hygiene water samples.