Volatile Dimethyl Polonium
Produced by Aerobic Marine
Microorganisms
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Abstract
The production of volatile polonium (Po<sub>v</sub>),
a naturally
occurring radioactive element, by pure cultures of aerobic marine
tellurite-resistant microorganisms was investigated. <i>Rhodotorula
mucilaginosa</i>, a carotogenic yeast, and a <i>Bacillus</i> sp. strain, a Gram-positive bacterium, generated approximately one
and 2 orders of magnitude, respectively, greater amounts of Po<sub>v</sub> compared to the other organisms tested. Gas chromatography-inductively
coupled plasma-mass spectrometry (GC-ICP-MS) analysis identified dimethyl
polonide (DMPo) as the predominant volatile Po compound in culture
headspace of the yeast. This species assignment is based on the exact
relation between GC retention times and boiling points of this and
other Group VI B analogues (S, Se, and Te). The extent of the biotic
Po<sub>v</sub> production correlates exponentially with elevated particulate
Po (Po<sub>p</sub>): dissolved Po (Po<sub>aq</sub>) ratios in the
cultures, consistent with efficient Po bioaccumulation. Further experimentation
demonstrated that some abiotic Po<sub>v</sub> generation is possible.
However, high-level Po<sub>v</sub> generation in these cultures is
predominantly biotic