MicrobeWorld App


Microbes After Hours


Click for more "Microbes After Hours" videos

Join MicrobeWorld

Subscribe via Email


Featured Image

Featured Video

Ebola Virus explained


ASM House 200X200

Chirality Tests Offer Approach for Resolving Viking Mars Questions

If the Viking labeled-release experiment on Mars in 1976 had tested glucose optical isomers separately, it might have avoided lingering doubts about its apparently positive results suggesting biological activity, say microbiologist Henry J. Sun of the Desert Research Institute in Las Vegas, Nev., and his collaborators. Some scientists say that experiments at two different landing sites detected life, whereas others believe that chemical oxidants in soils merely mimicked microbial activity. However, in recent earthly simulations, microbial specimens consumed only D-glucose, not its L isomer, whereas chemical oxidants such as permanganate showed no preference between these two mirror- image sugars, they report in a recent issue of Astrobiology. Thus, they recommend conducting such a chirality- based experiment on a future Mars mission.

Of course, adapting this kind of experimental procedure for transport to Mars or some other planet will be complicated and challenging. For example, how can it be engineered to protect the results from being compromised by terrestrial microbial contaminants? Sun suggests using nutrients that promote only short-term respiratory activity without cell division. "The best scenario would be to find that the opposite enantiomers are consumed, enantiomers that terrestrial microbes would not touch," he says.

Comments (0)

Collections (0)


American Society for Microbiology
2012 1752 N Street, N.W. • Washington, DC 20036-2904 • (202) 737-3600
American Society For Microbiology © 2014   |   Privacy Policy   |   Terms of Use