Antimony biomethylation by the wood rotting fungus Phaeolus schweinitzii

The wood rotting fungus, Phaeolus schweinitzii, efficiently transforms the antimony(III) compounds potassium antimony tartrate and antimony trioxide to nonvolatile dimethylantimony and trimethylantimony species. The organoantimony species were detected in potato dextrose broth media samples by using hydride generation-gas chromatography-atomic absorption spectroscopy (HG-GC-AAS). The average concentrations of trimethylantimony species after 40 days incubation with potassium antimony tartrate were approximately 35 μg, 155 μg and 520 μg Sb/1, for substrate concentrations of 10 mg, 100 mg and 1000 mg Sb/1 respectively. Thus, the maximum yield of trimethylantimony species was approximately 0.4%. When antimony trioxide (saturated solution, 4 mg Sb/l) was used as a substrate, the average concentration of trimethylantimony species was 150 μg Sb/l after 40 days. The HG-GC-AAS response for the dimethylantimony species was less than that for the trimethylantimony species; however, quantification was not possible because of the lack of an appropriate standard. In comparison, cultures of P. schweinitzii incubated with 1 mg As/l as sodium arsenite contained approximately 200 μg As/l as trimethylarsenic species, i.e. 20% yield. Biomethylation of antimony(V) was inefficient: cultures contained only 3 μg Sb/l as trimethylantimony species after incubation with 100 mg Sb/l as potassium hexahydroxyantimonate. No organoantimony species were detected in control cultures that contained only medium and inorganic antimony compounds. The identities of the organoantimony species were confirmed by using GC-Mass Spectrometry.