Search Results

Drinking water aboard spacecraft and on earth must be monitored to ensure that harmful bacteria are absent. NASA needs rapid methods for this purpose, to avoid possible launch delays and limit potential water-related health risks aboard spacecraft on orbit. Determination of bacterial viability after exposure to disinfection has significant health importance since oxidatively injured pathogenic bacteria have been shown to retain their virulence. This problem is compounded by the observation that injured bacteria are recovered at significantly lower frequencies using standard agar plate assays, leading to an underestimation of infection risks. Escherichia coli O157:H7 was exposed to 0.5 ppm free chlorine, retained on membrane filters and tested for physiological activity using a variety of assays.

Water is a critical commodity for spacecraft crews, requiring extreme conservation and reclamation strategies. In addition to suppression of the immune system in spaceflight, enhancement of bacterial growth and antimicrobial resistance in weightlessness raise serious concerns regarding microbial contamination of water systems. Rapid methods are needed for monitoring water, both pre-flight and on orbit. We are developing techniques to enumerate specific, metabolically active bacteria that may threaten crew health or lead to water system deterioration. Our methods are directed at the detection of individual bacteria, rather than populations of bacteria, and we aim to determine the identity of the organism as well as its physiological state con-currently. Our objectives are to determine, in a single test, the total number of bacteria present in a water sample, if a specific strain of bacteria is present within the total population and if these bacteria are viable or dead.