Barium is relatively abundant in the Earth's crust, but is found at low levels in aquatic environments due to
the insolubility of BaSO4 (barite) and BaCO3 (witherite). No biolgical role for barium has been identified in
prokaryotes, but protozoan ciliates of the genus Loxodes have organelles composed of barite crystals (Mueller's bodies) that
function as mechanoreceptors (Rieder et al, 1975; reviewed by Hemmersbach et al, 1999).
Dissolution of barite by microbial action has been demonstrated (Bolze et al, 1974), which could increase soluble barium levels in
environments (ToxFAQs: Barium). BaCl2 is commonly added to uranium mine
wastes to immobilize Ra+ in an insoluble Ba/RaSO4 co-precipitate (Fedorak et al, 1986).
The sulfate-reducing bacterium Desulfovibrio vulgaris can use barite as a sulfate source (McCready and Krouse, 1980) and can liberate both
Ba2+ and Ra2+ from Ba/RaSO4 precipitates (McCready et al, 1980).
For More Information:
Medline for barium metabolism AND bacteria
McCready RGL, Bland CJ, Gonzales DE. Preliminary studies on the chemical, physical, and biological stability of
Ba/RaSO4 precipitates. Hydrometallurgy. 1980;5:109-116.
McCready RGL, Krouse HR. Sulfur isotope fractionation by Desulfovibrio vulgaris during metabolism of BaSO4.
Geomicrobiol J. 1980;2:55-62.
Rieder HG, Schmitt G, Send W. Accumulation of barium in Mueller's bodies of the Loxodidae (Ciliata, Holotricha). Zeitschrift fuer