Formation of ordered dolomite in anaerobic photosynthetic biofilms

  title={Formation of ordered dolomite in anaerobic photosynthetic biofilms},
  author={Mirna Daye and John. A Higgins and Tanja Bosak},
8 Dolomite enabled the preservation of fine microbial textures in some Archean and Proterozoic 9 marine microbialites, but has rarely done so during the Phanerozoic. Here, we report precipitation 10 of dolomite in anoxygenic photosynthetic biofilms grown under chemical conditions relevant for 11 Archean seawater. Ordered dolomite nucleates primarily on the surfaces of photosynthetic cells 12 when manganese(II) is also present, nanocrystals of disordered dolomite form on exopolymeric 13… 
A new model for silicification of cyanobacteria in Proterozoic tidal flats
These experiments demonstrate that the exceptional silicification of benthic marine cyanobacteria analogous to the oldest diagnostic cyanobacterial fossils requires interactions among extracellular polymeric substances (EPS), photosynthetically induced pH changes, magnesium cations (Mg2+), and >70 ppm silica.
Modern dolomite formation caused by seasonal cycling of oxygenic phototrophs and anoxygenic phototrophs in a hypersaline sabkha.
A modern dolomite forming environment is examined, and it is found that a cyclic shift in microbial community between cyanobacteria and anoxygenic phototrophs creates EPS suited to dolmite precipitation, which provides new context for the interpretation of dolOMite throughout Earth's history.
Preservation of Organic Carbon in Dolomitized Cambrian Stromatolites and Implications 1 for Microbial Biosignatures in Diagenetically Replaced Carbonate Rock
17 Stromatolites have been a major focus in the search for ancient microbial life, however, the 18 organic carbon biosignatures of dolomitized stromatolites have not yet been fully characterized 19
Light-driven anaerobic microbial oxidation of manganese
Anoxygenic photosynthetic microorganisms can biomineralize manganese oxides without molecular oxygen being present and without high-potential photosynthesis reaction centres, which sheds doubt on proposed dates for the origins of oxygenic photosynthesis.
Microbial dolomite in culture experiment and natural environments: implication for dolomite genesis
Abstract The genesis of dolomite is a century-old mystery in sedimentology. The ‘microbial dolomite model’ proposed in recent years provides new insight into the study of dolomite genesis. However,
Anoxygenic phototrophs and the forgotten art of making dolomite
Dolomite [CaMg(CO3)2] is abundant in ancient rocks and rare in younger ones; why is unclear. Evidence is now emerging (Daye et al., 2019, p. 509 in this issue of Geology) that primitive microbes can
Systematic laboratory approach to produce Mg-rich carbonates at low temperature
Dolomite is a common Mg-rich carbonate in the geological record, but the mechanism of its formation remains unclear. At low temperature, the incorporation of magnesium ions into the carbonate
Searching for biosignatures in sedimentary rocks from early Earth and Mars
The recognition of past habitable environments on Mars has increased the urgency to understand biosignature preservation in and characterize analogues of these environments on Earth. In this Review,
Non‐classical crystallization of very high magnesium calcite and magnesite in the Coorong Lakes, Australia
The Coorong Lakes, South Australia, are one of the models for unravelling the ‘Dolomite Problem’. Critically, today only a few modern environments remain where large quantities of very high magnesium


Precipitation of low‐temperature dolomite from an anaerobic microbial consortium: the role of methanogenic Archaea
Here we report precipitation of dolomite at low temperature (30 °C) mediated by a mixed anaerobic microbial consortium composed of dissimilatory iron‐reducing bacteria (DIRB), fermenters, and
Microbial nucleation of Mg-rich dolomite in exopolymeric substances under anoxic modern seawater salinity: New insight into an old enigma
Sulfate-reducing bacteria are known to mediate dolomite formation under hypersaline conditions, but details of the crystal nucleation process are still poorly constrained. Our laboratory study
Aerobic microbial dolomite at the nanometer scale : Implications for the geologic record
Microbial experiments are the only proven approach to produce experimental dolomite under Earth's surface conditions. Although microbial metabolisms are known to induce dolomite precipitation by
Microbial biomineralization processes forming modern Ca:Mg carbonate stromatolites
Modern Ca:Mg carbonate stromatolites form in association with the microbial mat in the hypersaline coastal lagoon, Lagoa Vermelha (Brazil). The stromatolites, although showing diversified fabrics
Dolomite formation within microbial mats in the coastal sabkha of Abu Dhabi (United Arab Emirates)
Microbial mediation is the only demonstrated mechanism to precipitate dolomite under Earth surface conditions. A link between microbial activity and dolomite formation in the sabkha of Abu Dhabi has,
Microbial nucleation of calcium carbonate in the Precambrian
Microbial sulfate reduction is thought to stimulate carbonate precipitation in modern stromatolites, yet whether this metabolism was important in shaping Precambrian stromatolites is unknown. Here we
The Meaning of Stromatolites
Stromatolites document microbial interactions with sediments and flowing water throughout recorded Earth history and have the potential to illuminate the long-term history of life and environments.
Microfacies development in Late Archaean stromatolites and oolites of the Ghaap Group of South Africa
Abstract Organism-environment feedbacks in Precambrian platformal carbonates and reefs were strongly influenced by the activities of diverse microbial ecosystems. Microfacies studies of
The catalytic effect of bound extracellular polymeric substances excreted by anaerobic microorganisms on Ca-Mg carbonate precipitation: Implications for the “dolomite problem”
Abstract Because of its rare occurrence in modern sediments, as well as the difficulty in synthesizing it under low-temperature conditions in the laboratory, the origin of sedimentary dolomite has