Microbialite

Article By:

Foster, Jamie S. Department of Microbiology and Cell Science, Space Sciences Lab, University of Florida, Merritt Island, Florida.

Last reviewed:November 2019

DOI:https://doi.org/10.1036/1097-8542.422110

A mineral deposit formed by the interactions between microbes and their environment and thought to be one of the oldest ecosystems on Earth. Through the metabolic activities of microbialites, these ancient ecosystems have profoundly affected the evolution of Earth's environment, most notably contributing to the change in planetary redox (reduction–oxidation reaction) conditions and the rise of free oxygen in the atmosphere. To understand more fully the role of microbialites throughout Earth's history and potentially to reconstruct ancient environments, modern microbialites have been used as analogous ecosystems. Modern microbialites are found across the globe in a wide range of aquatic habitats, including freshwater, marine, and hypersaline environments, and can be classified according to their internal microstructures (see illustration). Most microbialites can be attributed to one of four major categories: stromatolites with laminated microfabrics; thrombolites with a clotted microfabric; dendrolites with branching structures; and leolites, which appear structureless. Together, these modern systems serve as important analogs to understand the biological and environmental processes associated with microbialite formation. See also: Depositional systems and environments; Ecosystem; Environment; Marine microbiology; Microbial ecology; Microbiology; Stromatolite

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