Biomethylation of Inorganic Antimony Compounds by an Aerobic Fungus:  Scopulariopsis brevicaulis

Various metals and metalloids can be converted by a variety of microorganisms to their volatile methyl derivatives. These bioconversions are important from an environmental perspective because they take place over long time periods and the products have quite different properties (e.g., transportation, toxicological) as compared to the inorganic species from which they are derived. Whereas the biomethylation of arsenic is well established, that of the closely related element antimony is not, and there are no reports of antimony methylation by monoseptic microbial cultures. We report here, for the first time, the formation of trimethylantimony [(CH3)3Sb] by a characterized microorganism, Scopulariopsis brevicaulis, grown aerobically in the presence of inorganic antimony. Volatile antimony evolved into the headspace above the fungal cultures was quantified by remote trapping and analysis by inductively coupled plasma−mass spectrometry (ICP−MS). The existence of biogenic trimethylantimony was established, following exclusion of oxygen from cultures after growth, by remote trapping of volatile compounds and analysis by gas chromatography with compound-specific (mass spectrometry) or element-specific (atomic absorption) detec tion. No other volatile product containing antimony was detected in culture headspace gases.