The response of extracellular enzymes to copper depends on the developing phase in the fungus Trametes versicolor.

Background: Human activities introduce organic and metallic contaminants in thecropped soils that can alter their functioning. Environmental risk assessmentneeds the development of tools to quantify the ecotoxicity of the contaminants.Among soil organisms, filamentous fungi produce enzymes involved in thebiogeochemical cycles. These enzymes may be used as indicators of fungalexposure to contaminants in soils.Aims: The present study aims to establish how the developing phases of thefungus Trametes versicolor modulate the expression of extracellular enzymes afterexposure to copper. For that purpose, it is necessary to monitor the activities ofselected enzymes during the fungal growing and the stationary phases withoutmetal contamination, then in the presence of the metal.Methods: Hydrolase activities (namely urease, arylsulfatase, acidic and alkalinephosphatases, b-D-glucosidase and N-acetyl-b-glucosaminidas) as well asoxidase activities (laccase, manganese and lignin-peroxidases) were measuredduring two weeks in liquid cultures of Trametes versicolor. Copper was addedeither during the growing or the stationary phases.Results: The results show that urease, b-D-glucosidase, acidic phosphatase andN-acetyl-b-glucosaminidase are mainly expressed during the growing phase ofthe fungus without metal spiking. By contrast, activities of the oxidases and b-galactosidase are increased during the stationary phase. Copper modify theexpression of the enzymes. As a general way, hydrolase activities are decreasedwhereas oxidase ones are strongly increased. The sensitivity of enzymaticresponses to copper depends on the development of the fungus and the type ofsecreted enzyme.Conclusion: The exposure of Trametes versicolor to copper modulate theexpression of its extracellular enzymes, whatever its developing phase. It is nownecessary to identify enzymatic profiles that could be used as tools for metalecotoxicity assessment.