Location
University of Nevada Las Vegas, Student Union Ball Room
Start Date
6-8-2009 9:30 AM
End Date
6-8-2009 12:00 PM
Description
The Viking mission showed that Martian soil can degrade a heterotrophic medium to carbon dioxide as if live microorganisms were present. The result is considered inconclusive, however, because abiotic oxidants, such as superoxides, may also exist on Mars and would explain the Viking result. One way to resolve this ambiguity is to repeat the Viking experiment with a isomerically pure medium. The consumption of one isomer, either D or L, would indicate biological activity. Indiscriminate destruction of both isomers would indicate abiotic redox processes. This idea was validated for glucose by REU research last summer (Sun et al. 2009). The objective of this project is to test this idea with amino acids. Specifically, the consumption rates of D- and Lenantiomers will be compared for histidine, lysine, and serine in selected bacteria, archaea, and eukaryotic fungi and yeasts. Results with Bacillus revealed that in histidine, only the L-isomer was consumed while for serine and lysine, both the D- and L-isomers were utilized. If confirmed in other microorganisms, these results indicate that histidine is a suitable substrate for Martian life detection but serine and lysine are not.
Keywords
Chemical oxidation; Extraterrestrial life; Histidine; Lysine; Mars; Martian soil; Microorganisms; Oxidation; Serine; Viking mission
Disciplines
Microbiology | Soil Science | The Sun and the Solar System
Language
English
Martian life detection with amino acid enantiomers
University of Nevada Las Vegas, Student Union Ball Room
The Viking mission showed that Martian soil can degrade a heterotrophic medium to carbon dioxide as if live microorganisms were present. The result is considered inconclusive, however, because abiotic oxidants, such as superoxides, may also exist on Mars and would explain the Viking result. One way to resolve this ambiguity is to repeat the Viking experiment with a isomerically pure medium. The consumption of one isomer, either D or L, would indicate biological activity. Indiscriminate destruction of both isomers would indicate abiotic redox processes. This idea was validated for glucose by REU research last summer (Sun et al. 2009). The objective of this project is to test this idea with amino acids. Specifically, the consumption rates of D- and Lenantiomers will be compared for histidine, lysine, and serine in selected bacteria, archaea, and eukaryotic fungi and yeasts. Results with Bacillus revealed that in histidine, only the L-isomer was consumed while for serine and lysine, both the D- and L-isomers were utilized. If confirmed in other microorganisms, these results indicate that histidine is a suitable substrate for Martian life detection but serine and lysine are not.
Comments
Abstract & poster