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The Diversity of the Original Prebiotic Soup: Re-Analyzing the Original Miller-Urey Spark Discharge Experiments
Project Investigators: Jeffrey Bada
Other Project Members
Adam Johnson (Doctoral Student)Summary
Recently obtained samples from some of the original Stanley Miller spark discharge experiments have been reanalyzed using High Pressure Liquid Chromatography-Flame Detection and Liquid Chromatography-Flame Detection/Time of Flight-Mass Spectrometry in order to identify lesser constituents that would have been undetectable by analytical techniques 50 years ago. Results show the presence of several isoforms of aminobutyric acid, as well as several serine species, isomers of threonine, isovaline, valine, phenylalanine, ornithine, adipic acid, ethanolamine and other methylated and hydroxylated amino acids. Diversity and yield increased in experiments utilizing an aspirating device to increase the gas flow rates; this could be applied as a simulation of prebiotic chemistry during a volcanic eruption. The variety of products formed in these experiments is significantly greater than previously published and mimic the assortment of compounds detected in Murchison and CM meteorites.
Astrobiology Roadmap Objectives:
- Objective 2.1: Mars exploration
- Objective 3.1: Sources of prebiotic materials and catalysts
- Objective 3.2: Origins and evolution of functional biomolecules
- Objective 3.4: Origins of cellularity and protobiological systems
- Objective 4.1: Earth's early biosphere
- Objective 4.2: Foundations of complex life
- Objective 5.1: Environment-dependent, molecular evolution in microorganisms
- Objective 6.2: Adaptation and evolution of life beyond Earth
- Objective 7.1: Biosignatures to be sought in Solar System materials
- Objective 7.2: Biosignatures to be sought in nearby planetary systems
Project Progress
Experiments were carried out to mimic the present Martian diurnal cycling of a Mg-Fe-Ca-Na-SO4 brine derived from acidic weathering of olivine-laden basalt. Experimental brines were laced with an enantiomeric excess of amino acids. Testing was done with and without exposure to the photolytic effects of UV radiation and utilizing a diurnal temperature cycle suitable for simulation of evaporation and sublimation processes in a Martian paleolake or permafrost system.
Results indicate that iron containing brines in the presence of UV are prone to increased levels of amino acid degradation due to photo-Fenton oxidation reactions. In the absence of UV, iron-rich brines provide enhanced preservation, with half lives 200-300% longer than systems lacking iron. Racemization half lives are 30 and 50 times greater than corresponding degradation half lives in iron and non-iron samples, respectively. These initial results provide interesting scenarios in the preservation of organic matter on Mars; an iron-rich subsurface groundwater system, such as those attributed to hematite concretion formation, may provide increased organic matter preservation. Additionally, a limiting factor in life detection may not be the detection of an enantiomeric excess of amino acids but detecting a pool of amino acids at all.
In addition to laboratory brines, we are studying a hydrologically closed basin system in southern California as a Mars analog environment. Samples from a long sediment core (30 meters) drilled at Soda Lake in the Carrizo Plain are being analyzed to determine the yield of enantiomeric excess of amino acids in lacustrine sediments dominated by interbedded clay- and sulfate-mineral assemblages. Obtained values will provide rates of amino acid racemization in environments dominated by seasonal to decadal cycles of evaporation and precipitation of sulfate and chloride minerals.
Stanley Miller's PhD thesis at the University of Chicago was published in 1955. He used three different experimental configurations (A, B, C). One (A) was the classic Miller spark discharge apparatus; another (B) incorporated an aspirating nozzle to increase the gas flow rate through the apparatus and the third (C) incorporated the aspirator device, but in place of the spark discharge electrodes it used a silent discharge device.Mission Involvement
MSLDetection of complex organic molecules, including amino acids and peptides, is a key goal of MSL. The Miller-Urey experimental products contain complex mixtures of organic molecules containing nitrogen. The Miller-Urey products are historically important and are scientifically important as analogs for abiotic organic matter delivered to Mars by meteorites or produced on Mars by hydrothermal reactions.- Amino Acid Preservation in Saline-Lake Sediments and Mars-Simulant Regolith
- Application of U-tube and fiber-optic distributed temperature sensor to characterize the chemical and physical properties of a deep permafrost and sub-permafrost environment at High Lake, Nunavut, Canada.
- Challenges for Coring Deep Permafrost on Earth and Mars: Drilling Project at High Lake, Nunavut, Canada
- Design, construction and testing of a Cavity-Ring Down Spectrometer for determination of the concentration and isotopic composition of methane
- Environmental genomics reveals a single species ecosystem deep within the Earth.
- High Lake Gossan deposit: An Arctic analogue for ancient Martian surficial processes?
- Isotopic Signatures of Methane and Higher Hydrocarbon Gases from Precambrian Shield Sites: A Model for Abiogenic Polymerization of Hydrocarbons
- Mars Forward Contamination Studies Utilizing a Mars Environmental Simulation Chamber
- Microbial Communities in Subpermafrost saline fracture water at the Lupin Au Mine, Nunavut, Canada
- Radiolytic oxidation of sulfide minerals as a source of sulfate and hydrogen to sustain microbial metabolism
- Saline Lakes and Gypsum Dunes in the Rio Grande Rift System as Analogues for Sulfate Deposits on Mars
- Stability of methane hydrates in the presence of high salinity brines on Mars
- The Diversity of the Original Prebiotic Soup: Re-Analyzing the Original Miller-Urey Spark Discharge Experiments
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