A rapid method to screen fungi for resistance to toxic chemicals

Although many species of fungi are able to degrade highly toxic chemicals, only a few species have been evaluated for resistance to toxic effects of these chemicals. In this paper we demonstrate the successful application of a method to rapidly screen several species of fungi for toxicity to chemicals or mixtures of chemicals using pentachlorophenol (PCP) as a model toxic compound. Cellulose antibiotic assay disks were soaked in solutions containing different concentrations of PCP (5, 10, 25, 50, and 80 mg l^–1) and then placed in a triangular pattern outside the growing edge of the mycelia of eighteen species of white rot fungi. The plates were incubated and observed for development of inhibition zones (non-growth areas) around the disks. The short-term (24 h) growth of all eighteen species of fungi was inhibited by 5–10 mg-PCP l^–1, a range similar to that observed using previously reported techniques. Long-term growth studies using this screening method were not useful since PCP diffused from the disk into the agar, decreasing the applied dose.