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Microbial mats microcosm to understand the differences and similarities between abiotic and microbially mediated minerals as signatures of life
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  • Óscar Cabestrero,
  • Cinthya Tebes-Cayo,
  • Cecilia Demergasso,
  • Nancy Hinman
Óscar Cabestrero
Universidad Católica del Norte, Universidad Católica del Norte, Universidad Católica del Norte

Corresponding Author:oscarcabestrero@gmail.com

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Cinthya Tebes-Cayo
Universidad Católica del Norte, Universidad Católica del Norte, Universidad Católica del Norte
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Cecilia Demergasso
Universidad Católica del Norte, Universidad Católica del Norte, Universidad Católica del Norte
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Nancy Hinman
Univ. of Montana, Univ. of Montana, Univ. of Montana
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Abstract

Microcosm experiments using microbial mats can be useful at times to understand mineral precipitation induced by microorganisms and their extracellular polymeric substances (EPS). Currently, the existing knowledge limits our ability to elucidate the interactions between microbes, which form communities as microbial mats, and minerals that precipitate in natural environments (e.g., lagoons, rivers, springs, soils). Much of the prior research did not consider entire microbial communities, despite recent evidence that microorganisms interact in a community-based way. This is especially relevant in extreme environments where the entire microbial communities are not yet known despite their relevance to biosignatures exploration on other planets. Here, we grew microbial mats on natural substrates in the laboratory to monitor changes in mat texture and mineral paragenesis. Several analytical techniques were used to compare mineral paragenesis in association with and without microbes. This paragenesis included major phases of chemical sedimentary deposits, such as gypsum, calcium carbonate, and some silicates, whose formation is traditionally linked to evaporative processes but was not in these experiments. In addition, some of the phases only precipitated within microbial mat samples and there were differences in mineral fabrics between mat samples and abiotic controls.