Microbial Dolomite Precipitation under Aerobic Conditions: Results from Brejo do Espinho Lagoon (Brazil) and Culture Experiments

Abstract

Microbially mediated high Mg-calcite and dolomite precipitation occurs under oxic conditions in Brejo do Espinho lagoon, Brazil, within the upper 5 cm below the sediment/water interface. With burial to < 25 cm in the sediment sequence, early diagenesis associated with sulfate reducing bacterial activity transforms the mixed carbonate mineralogy to 100% dolomite, as the pore water becomes undersaturated with respect to calcite, while remaining supersaturated with respect to dolomite. Laboratory culture experiments using moderately halophilic aerobic bacteria (Virgibacillus marismortui and Marinobacter sp.) isolated from the uppermost part of the microbial mat in Brejo do Espinho succinctly demonstrate that microbially mediated dolomite precipitation can occur under ambient Earth's surface conditions in the presence of oxygen.These results add an additional metabolic process, aerobic respiration, to bacterial sulfate reduction and methanogenesis, which have previously been identified with dolomite formation. Furthermore, the formation of carbonate minerals with spherulitic structures in both the natural environment and laboratory culture experiments points to microbial involvement, as recognized in numerous other modern environments and ancient systems. This study suggests that previously recognized modern dolomiteforming environments, such as the supratidal areas of Andros Island, Bahamas with Recent dolomite crusts, should be revisited to evaluate the importance of aerobic respiration in dolomite precipitation.

Carbonate and silicate biomineralization in a hypersaline microbial mat (Mesaieed sabkha, Qatar): Roles of bacteria, extracellular polymeric substances and viruses

“…Spheroidal structures have been described for many years now from microbial mats (e.g. Vasconcelos et al ., ; Dupraz et al ., ; Warthmann et al ., ; Sánchez‐Román et al ., ; Bontognali et al ., ; Bahniuk et al ., ), and their sizes are in the same range as those described in this study; tens of nanometres to microns. In some studies of mats and laboratory experiments involving bacteria and cultures (Sánchez‐Román et al ., ; Krause et al ., ; Zhang et al ., ,b; Rodriguez‐Blanco et al ., ), these spheroids are composed of dolomite or a very high Ca‐Mg carbonate (VHMC) interpreted as a precursor to dolomite (see Discussion of mineralogy in Gregg et al ., ).…”

Experimentally determined biomediated Sr partition coefficient for dolomite: Significance and implication for natural dolomite

“…There is evidence that some ancient and modern dolomite formation is related to microbial activity (Baker and Burns, 1985;Vasconcelos and McKenzie, 1997;Wright, 1999;Garcia del Cura et al, 2001;van Lith et al, 2003a;Roberts et al, 2004;Moreira et al, 2004;Wright and Wacey, 2005;Mastandrea et al, 2006;Sánchez-Román et al, 2008, 2009a. Microbial dolomite from culture experiments has been found to be closely associated with bacteria (van Lith et al, 2003b;Warthmann et al, 2000;Sánchez-Román et al, 2008, 2009b.…”

“…Bacteria have the capacity to adsorb ions, mainly Ca and Mg, on their cell envelope, creating micro-environments which induce the precipitation of minerals. This process does not occur in the absence of bacterial activity (e.g., Sánchez-Román et al, 2007, 2008, 2009a. Thus, bacteria can act as a nucleus for mineral precipitation by absorbing cations around the cellular surface membrane or cell wall (Morita, 1980;Ferris et al, 1991;Braissant et al, 2003;Sánchez-Román et al, 2008).…”

“…Recently, Sánchez-Román et al (2008, 2009a have shown that moderately halophilic aerobic bacteria (MHAB) mediate the precipitation of dolomite at room temperature. Further, they have demonstrated that sulfate ions do not hinder the formation of dolomite (Sánchez-Román et al, 2009b).…”

Evidence of a Role for Aerobic Bacteria in High Magnesium Carbonate Formation in the Evaporitic Environment of Dohat Faishakh Sabkha in Qatar

“…There is increasing evidence for the involvement of aerobic microorganisms in mediating dolomite formation (Sánchez-Román et al, 2007, 2011. Bacterial activity causes local supersaturation in the microenvironment surrounding the cell, and can overcome low-temperature kinetic barriers to dolomite precipitation (Van Lith et al, 2003;Sánchez-Román et al, 2009b). In fact, microorganisms exhibit the ability to create suitable microenvironments for microbially-mediated mineralization and recycling of metabolites, which has enabled them to adapt to a wide range of environmental conditions throughout the history of Earth, as widely discussed in the literature (Dupraz et al, 2009;Vu et al, 2009;De Carvalho and Fernandes, 2010;Zhang et al, 2013).…”