Searching for biosignatures using electron paramagnetic resonance (EPR) analysis of manganese oxides

Soon Sam Kim, John R. Bargar, Kenneth H. Nealson, Beverly E. Flood, Joseph L. Kirschvink, Timothy D. Raub, Bradley M. Tebo, Mario Villalobos

    Research output: Contribution to journalArticlepeer-review

    38 Scopus citations

    Abstract

    Manganese oxide (Mn oxide) minerals from bacterial sources produce electron paramagnetic resonance (EPR) spectral signatures that are mostly distinct from those of synthetic simulants and abiogenic mineral Mn oxides. Biogenic Mn oxides exhibit only narrow EPR spectral linewidths (∼500 G), whereas abiogenic Mn oxides produce spectral linewidths that are 2-6 times broader and range from 1200 to 3000 G. This distinction is consistent with X-ray structural observations that biogenic Mn oxides have abundant layer site vacancies and edge terminations and are mostly of single ionic species [i.e., Mn(IV)], all of which favor narrow EPR linewidths. In contrast, abiogenic Mn oxides have fewer lattice vacancies, larger particle sizes, and mixed ionic species [Mn(III) and Mn(IV)], which lead to the broader linewidths. These properties could be utilized in the search for extraterrestrial physicochemical biosignatures, for example, on Mars missions that include a miniature version of an EPR spectrometer.

    Original languageEnglish (US)
    Pages (from-to)775-786
    Number of pages12
    JournalAstrobiology
    Volume11
    Issue number8
    DOIs
    StatePublished - Oct 1 2011

    Keywords

    • Spectroscopic biosignatures

    ASJC Scopus subject areas

    • Agricultural and Biological Sciences (miscellaneous)
    • Space and Planetary Science

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