Volatile Dimethyl Polonium Produced by Aerobic Marine Microorganisms

摘要

The production of volatile polonium (Po_v), a naturally occurring radioactive element, by pure cultures of aerobic marine tellurite- resistant microorganisms was investigated. Rhodotorula mudlaginosa, a carotogenic yeast, and a Bacillus sp. strain, a Gram-positive bacterium, generated approximately one and 2 orders of magnitude, respectively, greater amounts of Po_v 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 VIB analogues (S, Se, and Te). The extent of the biotic Po_v production correlates exponentially with elevated particulate Po (Po_p): dissolved Po (Po_(aq)) ratios in the cultures, consistent with efficient Po bioaccumulation. Further experimentation demonstrated that some abiotic Po_v generation is possible. However, high-level Po_v generation in these cultures is predominantly biotic.