Polonium volatilization by tellurite resistant marine microorganisms

This study investigated several strains of tellurite resistant marine microorganisms for their potential to volatilize polonium (Po), a radioactive element. Polonium-amended microbial cultures were incubated in a volatile-trapping apparatus for ten days, after which Po was assayed in three phases (gas, liquid, and particulate/cells). Cultures that produced significant levels of volatile polonium (PoV) also displayed elevated particulate : liquid ratios. Two organisms, Rhodotorula mucilaginosa (a carotogenic yeast) and Bacillus sp. strain 6A (a Gram-positive bacterium), generated relatively high activities of PoV. Salt marsh model calculations indicate that the Po volatilization rates observed here could explain a significant fraction of excess Po in the local coastal atmosphere. Additional experiments in this study tested whether PoV production in cultures of R. mucilaginosa and Bacillus sp. strain 6A result from biotic or abiotic mechanisms. Cultures treated chemically or physically to inactivate cellular processes provided somewhat mixed results. These observations led to the hypothesis that abiotic reactions constitute low level volatile Po production, while high level production is most evident as biotic, most likely either as enzyme-driven processes or requiring metabolic turnover.