Microorganisms in Evaporites: Review of Modern Geomicrobiology

Abstract

The “geomicrobiology” of evaporites—microorganisms and associated biomaterials preserved in saline minerals—has seen great progress over the past decade. There are many new reports of culturing archaea and bacteria (Stan-Lotter et al. 1999, 2002; Vreeland et al. 2000, 2007; Mormile et al. 2003; Gruber et al. 2004; Schubert et al. 2009b, 2010a; Gramain et al. 2011), sequencing prokaryote DNA (Radax et al. 2001; Fish et al. 2002; Park et al. 2009; Panieri et al. 2010; Gramain et al. 2011), and identifying organic compounds such as beta carotene and cellulose (Griffith et al. 2008; Schubert et al. 2010b; Lowenstein et al. 2011) from ancient samples of halite (NaCl) and gypsum (CaSO₄ · 2H₂O). Tiny droplets of brine trapped within evaporite minerals, called fluid or brine inclusions, seem to be an important, but not exclusive, haven for microbes and biomaterials in buried evaporites. Given the expanded interest in microbial life in evaporites, and the potential implications regarding the search for life in the solar system, it seemed worthwhile to summarize the most important findings in the geomicrobiology of evaporites. The last such summary of advances in the geomicrobiology of ancient evaporites was by Vreeland and Powers (1999), so the focus here is on the last 10 years.