title: Physiological responses to nanoCuO in fungi from non-polluted and metal-polluted streams.
abstract: Nanocopper oxide (nanoCuO) is among the most widely used metal oxide nanoparticles which increases their chance of being released into freshwaters. Fungi are the major microbial decomposers of plant litter in streams. Fungal laccases are multicopper oxidase enzymes that are involved in the degradation of lignin and various xenobiotic compounds. We investigated the effects of nanoCuO (5 levels, ≤ 200 mg L(-1)) on four fungal isolates collected from metal-polluted and non-polluted streams by analyzing biomass production, changes in mycelial morphology, laccase activity, and quantifying copper adsorbed to mycelia, and ionic and nanoparticulate copper in the growth media. The exposure to nanoCuO decreased the biomass produced by all fungi in a concentration- and time-dependent manner. Inhibition of biomass production was stronger in fungi from non-polluted (EC₅₀(10 days) ≤ 31 mg L(-1)) than from metal-polluted streams (EC₅₀(10 days) ≥ 65.2 mg L(-1)). NanoCuO exposure led to cell shrinkage and mycelial degeneration, particularly in fungi collected from non-polluted streams. Adsorption of nanoCuO to fungal mycelia increased with the concentration of nanoCuO in the medium and was higher in fungi from non-polluted streams. Extracellular laccase activity was induced by nanoCuO in two fungal isolates in a concentration-dependent manner, and was highly correlated with adsorbed Cu and/or ionic Cu released by dissolution from nanoCuO. Putative laccase gene fragments were also detected in these fungi. Lack of substantial laccase activity in the other fungal isolates was corroborated by the absence of laccase-like gene fragments.
authors: Centre of Molecular and Environmental Biology (CBMA), Department of Biology, University of Minho, Campus of Gualtar, 4710-057 Braga, Portugal.
authors: Arunava
authors: A
authors: Pradhan
authors: Sahadevan
authors: S
authors: Seena
authors: Dirk
authors: D
authors: Dobritzsch
authors: Stefan
authors: S
authors: Helm
authors: Katharina
authors: K
authors: Gerth
authors: Melanie
authors: M
authors: Dobritzsch
authors: Gerd-Joachim
authors: GJ
authors: Krauss
authors: Dietmar
authors: D
authors: Schlosser
authors: Cláudia
authors: C
authors: Pascoal
authors: Fernanda
authors: F
authors: Cássio
mesh_terms: D000327:Adsorption; D001203:Ascomycota / Q000187:drug effects* / Q000254:growth & development; D018533:Biomass; D003300:Copper / Q000378:metabolism / Q000633:toxicity*; D005656:Fungal Proteins / Q000378:metabolism; D042845:Laccase / Q000378:metabolism*; D053768:Metal Nanoparticles / Q000633:toxicity*; D008855:Microscopy, Electron, Scanning; D025282:Mycelium / Q000187:drug effects / Q000254:growth & development; D016133:Polymerase Chain Reaction; D011174:Portugal; D045483:Rivers / Q000382:microbiology; D013045:Species Specificity; D013052:Spectrometry, X-Ray Emission; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*
chemical_list: D005656:Fungal Proteins; D014874:Water Pollutants, Chemical; D003300:Copper; D042845:Laccase; C030973:cupric oxide
keywords: Biosorption; Fungal biomass; Laccases; Mycelial morphology; NanoCuO