Oxidation of triphenylarsine to triphenylarsineoxide by Trichoderma harzianum and other fungi

Arsenic resistant strains of bacteria and fungi were isolated from soil con taminated by chemical warfare agents. Until now, no metabolic products of m icrobial attack against the phenyl residues of the model substrate tripheny larsine (TP) were found if it was incubated together with these strains in liquid culture assays. However, one of the isolated fungi, Trichoderma harz ianum As 11, was found to oxidize TP to triphenylarsineoxide (TPO). The yea st Trichosporon mucoides SBUG 801 and the white-rot fungus Phanerochaete ch rysosporium were also able to oxidize the As(III) in TP. In addition, P. ch rysosporium transformed phenylarsineoxide (PAO) to phenylarsonic acid (PAA) under O-2-atmosphere. By means of a respirometer system, the oxidation of TP by T. harzianum As 11 was confirmed by a significantly higher consumptio n of oxygen in the presence of these compounds. HPLC analysis of the oxidat ion products TPO and PAA in the medium of the assays provided evidence for the transfer reaction of As(III) to As(V) in organic bonds. The oxidation p roducts TPO and PAA are more hydrophilic than TP and PAO. Therefore, it was concluded that particular fungi contribute to the mobilization of arsenic in soil contaminated by chemical warfare agents. (C) 2001 Elsevier Science Ltd. All rights reserved.