impact of copper and zinc on the growth of saprotrophic fungi and the production of extracellular enzymes

To assess the impacts of Cu and Zn on fungi, we tested the growth of 18 taxonomically different saprotrophic (basidiomycete, ascomycete and zygomycete) fungi and their production of extracellular oxidative enzymes on Cu(0, 100, 200, 400 mg kg–1) or Zn(0, 100, 200, 400 mg kg–1) containing ABTS (2,2 ́-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) agar plates. Coniothyrium sp. was the most tolerant ascomycete and Sordaria sp. the most sensitive to both Zn and Cu. The growth of 8 basidiomyceteous fungi was reduced by 22%–100% on ABTS plates with 200 mg Cu kg–1. Bioluminescent Saccharomyces cerevisiae yeast tests showed that Cu was 7-fold more toxic than Zn. Dose responses with respect to enzyme production varied among ascomycetous, zygomycetous and basidiomycetous fungi. Cu was more toxic than Zn for all tested fungi with all methods indicating that microbial functioning of soil is more vulnerable to Cu than Zn in the soil.