Factors affecting trimethylarsine and dimethylselenide formation byCandida humicola.

Selenite, selenate, and tellurate inhibited the conversion of arsenate to trimethylarsine byCandida humicola. Trimethylarsine disappeared from the gas phase when incubated withC. humicola in the presence of selenium or tellurium salts. The fungus generated dimethyl-selenide from selenite and selenate and an unidentified gas from tellurate. Sulfate but not arsenate, tellurate, or phosphate inhibited the conversion of selenate to dimethylselenide. Arsenate-grown cells generated trimethylarsine from arsenate, and selenate-grown cells formed dimethylselenide from selenate with almost no lag phase. Cells grown in media with selenate or with no additions only formed the alkylarsine from arsenate after a lag phase, and those grown in solutions with arsenate or no additions produced dimethylselenide slowly from selenate.