0418758 This project seeks to verify geological evidence that microorganisms can survive inside the brine-filled inclusions of halite crystals for periods of 10^8 years. The goal of the research is to obtain absolute radiometric ages of brine inclusions from two ancient halites from which microorganisms have been previously cultured: crystals from the Permian Salado Formation, New Mexico and "chevrons" from the Cretaceous Muribeca evaporites of Brazil. Such dating will remove doubts about the ages of the fluid inclusions from which the purported Permian and Cretaceous microorganisms were extracted. Obtaining absolute ages of brine inclusions in halite has profound implications for long-term bacterial survival on Earth and for astrobiology, and may contribute techniques to future exploration for life on Mars and other parts of the solar system.
The purported world's oldest living organism, the spore-forming bacterium Virgibacillus sp. Permian strain 2-9-3, was cultured from a brine inclusion in halite cement of the 250 Ma Permian Salado Formation. Rb-Sr dating of individual brine inclusions from these samples will establish unequivocally whether Virgibacillus sp. 2-9-3 was trapped in a fluid inclusion at the time of deposition of the Salado salts. Archaeal strains have been cultured from brine inclusions from primary chevron halite of the Cretaceous Muribeca Formation. Dating brine inclusions in these Cretaceous halites by Rb-Sr methods will ascertain with certainty whether the brine inclusions that yielded the newly discovered halophilic Archaea are >100 Ma in age.
The information obtained from this grant is disseminated to the research community as presentations at national meetings and as journal articles. The results are illustrated in a geobiology seminar offered each year to graduate/undergraduate students at Binghamton, and in an analytical geochemistry course co-taught at UT. The Principal Investigator participates in a summer enrichment program for K-12 students with field and laboratory work on microorganisms in the environment, including microscope and Environmental Scanning Electron Microscope viewing of an assortment of samples including brine inclusions in salt. A website on microbial life and preservation in brine inclusions features current research from this project.
(Collaborative research with Riciputi/0418651/Univ. Tennessee at Knoxville)
