Aspergillus niger and Penicillium chrysogenum were able to grow on Czapek Dox medium amended with elevated concentrations [up to 500 ppm active ingredient (ai)] of the fungicide copper oxychloride. Solubilization of the fungicide in solid medium was evident by the appearance of a clear (halo) zone underneath and around the growing colonies. The halo formed with A. niger, grown on fungicide-containing nitrate nitrogen medium, was found subsequently to enclose concentric rings of newly crystalline precipitate. These crystals were extracted, examined by scanning electron microscopy and IR, and identified as copper oxalate. The supplemented nitrogen source to the medium greatly affected both fungicide solubilization and fungal tolerance. Ratios of fungicide solubilization rate (R(S)) in relation to the colony growth rate (R(G)) were significantly higher on ammonium than on nitrate nitrogen medium for both fungal strains. Growth ratios (the colony extension rate in the presence of a given concentration of the fungicide in relation to the control colony growth rate) of A. niger were markedly lower on ammonium than on nitrate nitrogen medium. The cellular copper contents, taken up from the fungicide, and the medium titratable acidity were higher in ammonium than in nitrate medium for both fungi. These results suggested fungal possession of variable tolerance mechanisms to this fungicide by complexation and/or precipitation of copper in the medium. Additionally, this work emphasizes the activity of fungi in transformation of insoluble inorganic metal-containing fungicides into insoluble organic metal compounds, which has a potentiality in metal cycling in biogeochemical and environmental context.

The use of disinfectants has drastically increased in response to the growing public awareness of risks of microbial infection. However, this practice has a negative impact on the environment as it results in dumping large volumes of antimicrobial and microbicidal compounds in aquatic and terrestrial ecosystems. Chloroxylenol (PCMX) is a phenolic compound that poses public health and environmental risks art high concentrations. Here, a novel disinfectant was proposed to increase the lethality of PCMX by adding copper (Cu) to it. However, it was necessary to demonstrate that this mixture is fungicidal and not merely fungistatic, and that the addition of Cu does, in fact, increase PCMX lethality. We evaluated the fungicidal efficacy of PCMX/Cu on Candida albicans. PCMX/Cu synergy was explored on biofilm formation, biochemistry, and morphology of C. albicans. Inhibition increased with PCMX increased concentration. The combination of Cu and PCMX disrupted fungal ultrastructure, biofilm formation, and biochemical characteristic.