The transformation of arsenicals by Candida humicola.

An analytical procedure for the separation, detection, and identification of some of the compounds produced by a cell preparation of the fungus Candida humicola from 74As-arsenate, [14C]-methylarsonate, and [14C]-dimethylarsinate has been devised and tested. It has been possible to detect five distinct 74As-containing compounds following the incubation of 74As-arsenate with a broken cell homogenate, three of which have been identified as arsenite, methylarsonate, and dimethylarsinate. With [14C]methylarsonate as substrate, [14C]dimethylarsinate and [14C]trimethylarsine oxide are produced. Products from [14C]dimethylarsinate include [14C]methylarsonate and [14C]trimethylarsine oxide as well as an unknown species. The absence of any transformation when buffer replaces the cell preparation implicates these various compounds as intermediates in a biological synthesis of trimethylarsine.