Production of dimethyl triselenide and dimethyl diselenenyl sulfide in the headspace of metalloid-resistant Bacillus species grown in the presence of selenium oxyanions.

A Bacillus species harvested from the environment is metalloid resistant and, when grown anaerobically in complex growth medium and amended with the selenium oxyanion selenate, selenite, or selenocyanate, produces volatile organoselenium compounds in bacterial culture headspace. Two novel compounds so far undetected in bacterial culture headspace, CH3Se2SCH3 and CH3SeSeSeCH3, are produced and can be detected using solid-phase microextraction and gas chromatography with either fluorine-induced chemiluminescence or mass spectrometric detection. Differences in the electron impact fragmentation pattern of the mixed sulfur/selenide compounds allow the tentative differentiation between the symmetric and asymmetric isomers in this bacterium's headspace in favor of the asymmetric CH3SeSeSCH3 isomer.