NTB: What makes these bacterial endospores so resilient??
Dr. Ponce: That’s a good question. And that’s a matter of active research. It’s not something that I actively research, but colleagues of mine do and it’s a matter of debate.
One thing that is notable about spores is that there are many layers that basically shield the DNA and the internal part of the cell from the environment. The other thing is that basically they’re dehydrated. Most of the water has been extruded from the spores, so they’re very dry and they’re basically mineralized with calcium dipicolinate, which is something that we ultimately take advantage of in our detection scheme because we detect that dipicolonate in the spores.
NTB: How does NASA currently detect the presence of bacterial spores on its spacecraft?
Dr. Ponce: Well, right now there’s something called the NASA Standard Assay, and it’s based on culturing organisms that have been swabbed from a surface on a growth medium – Tryptic Soy Agar is what it’s called – and you basically incubate that for several days after a heat shock to kill off vegetative cells, and that’s how you enumerate how many spores – viable spores – are on the spacecraft in terms of culturable, colony forming units.
NTB: That process, I assume, is time consuming compared to your new method?
Dr. Ponce: As I mentioned, it is quite time consuming and labor intensive. It takes two to three days before the colonies become visible for counting and, of course, you have to wait that period of time before results become available. And it also takes a person with skill to handle those samples carefully.
In our case, we can run our assay in a timescale of 15 minutes from sampling to results. Also, because the chemistry of our detection assay is quite simple, we’ve been able to automate that, in essence taking a lot of the manual function out of the hands of an individual and placing it with an automated system.
NTB: You’re currently working with a company in Massachusetts called Advanced Space Monitor on developing a portable instrument that could be used by the Department of Homeland Security in the event of a biological attack. Tell us about that project and how close you think you are to producing a marketable product.
Dr. Ponce: That’s a good question. We are going into Phase 3 right now, the last phase for a Homeland Security project, where we’re developing an automated instrument that is intended to be deployed after a biological attack to help folks who are responsible for the cleanup determine whether or not the sterilization regimen was effective. We’ve developed a prototype instrument in Phase 2, and now in Phase 3 we’re developing the final prototype that will actually be deployed in clean rooms to make sure that it works, and we’ll be sending it to a third party.
Advanced Space Monitor is involved because they’ve licensed the technology and they are looking to generate prototype instruments for Homeland Security, but also for other commercial applications that are out there because, again, it’s not just the biodefense market, so to speak, it’s wherever sterility and hygiene are important. I mentioned a few of the industries and they include the hospital industry, the healthcare and food preparation industries, also the pharmaceutical industry is required to make sure their environments are cleaned to a certain threshold and are free of microorganisms.
NTB: Could this new technology you’ve developed someday be used to search for the presence of life on other planets?
Dr. Ponce: Yes. I mean, NASA ultimately is interested in achieving its main goals, and one of those is to search for life on other planets. The technology fits in two-fold. One is that when we send life-detection instruments to other places like Mars or Europa, for example, we want to make sure that we’re not detecting life that has been piggybacked on the spacecraft. In other words, we don’t want to get a false positive with the stuff that we carried on. Where our technology ties into this is planetary protection – making sure that spacecraft are clean. By giving planetary protection better tools for the future, I think we’ll reduce the risk of contamination. That’s one area that we fit into.
Secondly, what we’re doing is we’re looking at how life can survive in extreme environments on Earth. So one thing that we do is we go to the Atacama Desert in Chile. Or Kilimanjaro in Tanzania, to see how the toughest form of life – these spores – can survive in extreme environments, kind of setting the boundary conditions for life. That has relevance. Those are considered Mars analog sites. Without actually going to Mars, this is as close as we can get on Earth.
That might be a tough goal to achieve, having our technology embedded or be part of an actual mission. I suspect that because detecting endospores is so earthcentric in nature, that it would likely not be the first life detection mission to go out. But one can envision that if there is a positive detection of life, you might subsequently ask, “Well what kind of life is it?” The most likely life that could survive, you know, there’s this theory of Panspermia where early life on Mars and Earth was exchanged by a meteorite. If that type of mechanism was operating, then the most likely organisms to be exchanged in such a process would be endospores because they’re the most likely to survive the ejection from one planet, the transfer through space, and then crashing through the atmosphere of Earth or Mars.
So that’s kind of how I see it. All of these technologies that we’re developing for endospore detection and testing whether or not they’re alive or dead, really have applications for planetary protection, astrobiology, for life on Earth, and ultimately for missions far in the future.