NTB: Does LOCAD-PTS have a shelf life, or can it be used repeatedly?
Flores: It does have a shelf life. It has been shown to be stable for minimum of two years, and we are monitoring it on going with ground tests to see if that shelf life can be extended. They cannot be used repeatedly; a cartridge is disposable and for a one-time use. But due to their size - they are very small, very lightweight - you can take as many as you need into the field or into space to perform multiple analyses.
NTB: How does it differ from a conventional Petri dish?
Flores: A Petri dish contains a microbial growth media, and it cultures living, or viable, microorganisms. So after a few days growth, the colonies, which are also called colony-forming units (CFUs), and then they are analyzed to attain an indication of the number of the microorganisms present. It is estimated that up to about 95% of microorganisms on earth and, potentially, on the ISS, however, are "un-culturable." They are extremely difficult to grow in the lab, and have to have specific growth media.
The LOCAD-PTS is a non-culture-based technique that makes it very useful, that's very complementary to the current culture-based method. And also, and this is interesting-it makes no differentiation between dead and live cells. Petri dishes just detect live cells. Detection of dead biological material can be just as important to detect the presence of endotoxins on surfaces that need to be free of all biological material. An example would be, in the future, when we detect for life on other planets as part of our planetary protection program. We look to LOCAD-PTS as a payload on stations, as a pathfinder that can take us forward as we have other challenges in our exploration missions.
NTB: LOCAD-PTS is currently on the ISS; what, if any, are the results?
Flores: Operations for LOCAD-PTS will not begin until spring of 2007, so right now it is just stowed. Right now we are taking baby steps. Crew health diagnostics on the shuttle or ISS would be a crosscutting application that we would like to pursue. Right now, we will just be swabbing for surfaces that crewmembers do touch, so that could be an application for the future. Our main concern, when we do operate, will be that all the components of the system function normally, that we can acquire the sample, that we do not have any issues in microgravity, etc. We have performed numerous tests in our parabolic environment, and have not seen any issues to date. We want to make sure that our analysis is consistent, and we will be doing side-by-side correlation with the current culture-base method. And we expect a positive correlation between LAL and endotoxin values, between the LAL-endotoxin values and CFUs. But we do not expect it to be a very high one, because there are fundamental differences between what each method measures.
The project is a good example of how you can streamline an investigation for space. And I think that the strength of the project has been the collaborative side: we essentially have had involvement from the commercial industry, from academia, from NASA agencies, so I believe that this is a nice example of low-cost, streamlined projects leveraged off of prior work.
NTB: Can the LOCAD-PTS target a specific microbe?
Flores: It can. That's one of the advantages, and shows the versatility of the instrument. You can design the formulations for specific bacteria, fungi, yeast, or mold, in addition to families of such. For example, you could design a cartridge that detects specifically for salmonella or E. coli.
NTB: Could the NASA device be applied in terrestrial medicinal diagnoses?
Flores: Yes, and it already is. The PTS is already available commercially, and it is a great instrument for use in hospital wards, maintaining food hygiene, in genetics where you have to verify endotoxin levels in your preparation. Overall, it is a tool that is used in the pharmaceutical industry for cleanliness, and also manufacturing.
And the NASA-modified instrument could be applied on Earth as well. In fact, some of the NASA modifications that we've made in their commercial unit have been adopted, where we have made it more robust for space flight and made some material changes and internal changes to the unit.
For more information, contact Ms. Ginger N. Flores at
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