Precipitation of barite by marine bacteria: A possible mechanism for marine barite formation

Abstract

Barite (BaSO 4 ) is found throughout the ocean, yet seawater is undersaturated with respect to barite, and organisms that could account for the abundance of barite have not yet been identifi ed. The mechanism for barite formation in seawater is not fully understood. Here we show that marine bacteria have the ability to precipitate barite through a metabolically mediated biomineralization process. We precipitated barite in laboratory experiments in the presence of several strains of marine bacteria grown on yeast media enriched with barium (Ba); barite did not precipitate under identical conditions in killed-bacteria controls. The crystals develop from amorphous, phosphorous-rich spherical precursors with fi brous internal textures, common in bacterial mineral precipitation. Bacterial mediation of barite precipitation can explain the distribution of barite in the water column and the occurrence of barite crystals in organic-rich sinking aggregates where bacteria are concentrated. This fi nding has implications for the use of barite and Ba proxies in paleoceanographic research.

Controls on stable Sr-isotope fractionation in continental barite

“…It is clear that the presence of microbes, organic substances, or other minerals plays a major role in barite precipitation at all three sites in this study supporting the hypothesis that heterogeneous nucleation and crystal growth is an important process. This mechanism is also likely important for barite formation in other settings such as marine hydrothermal environments or the ocean water column (e.g., Sanz-Montero et al, 2009;González-Múñoz et al, 2012).…”

Role of bacteria in marine barite precipitation: A case study using Mediterranean seawater

“…In a warm sulfur spring in Canada, Bonny and Jones (2008) reported barite crystals that nucleated on microbial cell surfaces and in microbial extracellular polymeric substances (EPS), suggesting that microbes are capable of adsorbing and bioaccumulating barium. Recently, González-Muñoz et al (2012) demonstrated that marine bacteria promoted barite precipitation under laboratory conditions. These authors assayed marine bacteria for experimental work, using selected strains with proven biomineralization capability such as Idiomarina (González-Muñoz et al, 2008), as well as other strains of Gram-negative and Gram-positive bacteria.…”

Southern Hemisphere control on Australian monsoon variability during the late deglaciation and Holocene

“…To further evaluate a possible bias of the Ca-normalized variability of terrigenous elements, we additionally normalized against Ba ( Supplementary Fig. 5), which is related to particulate organic matter and/or the precipitation of barite by marine bacteria 39,40 and, thus, has no direct relation to carbonate flux. In previous records from the NW Australian margin, CaO 3 and organic productivity indicators such as C org and chlorins did not show any positive correlation 41 (Core MD01-2378).…”