Science Buddies: "Ask an Expert"

Hello. My science fair project consists of using a Dissimilatory Perchlorate Respiring Bacteria, specifically Dechloromonas Aromitica strain RCB, to reduce ammonium perchlorate on the surface of Mars. Perchlorates are toxic to humans and cover every inch of the surface of Mars. The Mars One project is suppose to send two astronauts to Mars in the next decade. Although astronauts wear special protective suits, perchlorates still pose a hazard to the health of anyone near them. So I am in the process of designing an experiment. I know through perchlorate respiration, oxygen and chlorine are produced. And with the Martian's atmosphere being nearly 97% carbon dioxide, I figured the production of oxygen would actually help with life coming back to Mars later in the future. So my project hits two birds with one stone. Not only do I make Mars safer for us, I can also improve the chances of it being inhabitable by other forms of life in the future. I'm having trouble though with several aspects of this project. First, I don't know how to grow this bacteria. MicrobeWiki didn't help much. I plan on cutivating this bacteria and don't know what it likes to grow in or around. I plan on also placing it some kind of solution with ammonium perchlorate. I just don't know what this solution is or what it should consist of. And lastly, I need to be able to measure, over time, if there is any increase of oxygen, for this will indicate perchlorate respiration is taking place. So in conclusion, I need to know what environment is best for this strain of bacteria to grow in, what should the solution consist of, and what device is highly sensitive enough to measure small increases in atmospheric oxygen levels. Thanks to anyone who can assist me with my project. It is definitely appreciated. Have a great day!

What a great idea! You may be on the first mission to Mars with your project to test bacterial terraforming.

I had to look up Dechloromonas. That's not a bacterium I had heard of. It has some very interesting and useful metabolic activities including, as you said, decomposing perchlorate and releasing oxygen. As for how to grow it, you're right--methods are hard to find. I tried PubMed and found some free-access papers that have Methods sections detailing the growth conditions:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2744828/
http://www.ncbi.nlm.nih.gov/pubmed/?ter ... egradation
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC124121/

One thing I noticed was that the papers seem to use Dechloromonas agitata rather than D. aromatica. Is there a reason why you picked aromatica rather than agitata?

I am assuming that you will be able to do your experiments in a microbiology lab. You'll need some special culture vessels that will allow you to grow the bacteria in a liquid medium containing perchlorate while collecting the oxygen that comes off. There are instruments that can measure oxygen concentration but they are expensive. I don't know of a relatively simple, inexpensive method for O2 assay but maybe one of the other experts can suggest something.

I'm sure you will have more questions, so don't hesitate to post again and we will try to help you.

Good luck!

Sybee