Microbial mats microcosm to understand the differences and similarities
between abiotic and microbially mediated minerals as signatures of life
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.