Microbes and marine sediments: a lifelong relationship on Earth's Biosphere

PAN, JERÓNIMO

Microbes: the Foundation Stone of the Biosphere

Springer

Lugar: Cham; Año: 2021; p. 57 - 88

The relationship between microbes and marine sediments probably datesback to the very origin of life on Earth. This intimate association is exemplified byhow the physical and geochemical environment within sediments determines whichmicrobes dominate a certain consortium and, in turn, how microorganisms haveprofound effects on sediment properties through their metabolic activities at various(spatial and temporal) scales. Microbial mats, the oldest ecosystems on Earth with afossil record dating back to 3.4 Ga, are biosedimentary structures in which microbesexploit all environmental niches that arise in relation to strong gradients in light,redox potential, the concentration of viable substrates for energy acquisition, as wellas toxic compounds. In fact, microbial mats have been thought to be the environmentwhere several metabolic pathways evolved, establishing microbial lineages andbiogeochemical processes that last to this day. This chapter provides a concise summary of the evolution of those early microbial lineages, to then revisit modern,hypersaline microbial mats, and some of the microbially induced sedimentarystructures (MISS) that arise from mats colonizing siliciclastic sediments. Salientecological features and the metabolism of their microbes are briefly discussed, whileemphasis is made on what can be learned from their study through the actualisticperspective of GeoBiology. Emergent properties of microbe-sediment interactionsessential for the development, establishment, and preservation of microbial mats inmodern and fossil settings are discussed.