described the opening of aromatic rings via the homogentisate pathway. However, strain CBS 121818 of E. sideris, which was isolated by toluene enrichment, was unable to grow on this compound when supplied as the sole carbon and energy source. Nevertheless several strains were isolated by toluene enrichment. A possible explanation might be that the species is less susceptible to toxic substrates than competing, rapidly growing cosmopolitan fungi. In relation to this, E. sideris appears to be consistently tolerant to arsenate, with very similar IC50 values between the strains arising from arsenic rich environments and the type strain isolated from the phyllosphere. Arsenate is the dominant form of arsenic in aerobic soils and, in physico-chemical terms, is an analogue of phosphate. Because of this, arsenate enters the cell through the same membrane transport system as phosphate and competes with the latter for binding to ADP. The resulting ADP–As complex disrupts the energy flow and can ultimately lead to cell death (Rosen 2002). Literature data on the toxicity of arsenic oxyanions is scarce for fungi. A few studies on the growth inhibitory effect of arsenate in phosphate rich fungal liquid cultures have reported significant toxicity at concentrations below 500 mg As L−1(Chen & Tibbett 2007).