Tolerância de um isolado fúngico de trichoderma asperellum ao zinco e o cobre

Abstract

The spread of heavy metals in the environment harms living beings and ecosystem processes. Although a certain amount of copper and zinc is required by living beings, in high amounts they affect cellular functioning, causing serious health complications. For this reason, it is necessary to use efficient techniques to remove contamination from the medium. Among the forms of depollution, one can make the combined use of techniques such as the use of fungi associated with phytoremediation processes. Fungi of the genus Trichoderma are good promoters of plant growth, as they are versatile in colonizing the environment, improving plant growth and eliminating pathogens. Fungal tolerance is an important feature for microorganism-assisted phytoremediation processes. Therefore, this work aimed to evaluate the tolerance of a fungal isolate of Trichoderma asperellum to zinc and copper, aiming to improve the conditions of biodegradability of these metals. For this evaluation, the fungal strains were exposed to increasing concentrations of zinc (360 mg∙L-1, 720 mg∙L-1, 1080 mg∙L-1, 1440 mg∙L-1, 1800 mg∙L-1) and copper (200 mg∙L-1, 400 mg∙L-1, 600 mg∙L-1, 800 mg∙L-1, 1000 mg∙L-1) in solid culture medium for 5 days. The effect of Cu and Zn on T. asperellum was estimated through the percentage of reduction in growth and the differences of each treatment. T. asperellum survived up to 1000 mg∙L-1 of copper with a reduction of 69.11% at 800 mg∙L-1, whereas for zinc, T. asperellum was able to survive up to 1800 mg∙L-1, with a reduction of 71.36% at 720 mg∙L-1. The application of fungi of the genus Trichoderma increases the phytoremediation potential, since they improve the plant defense system and control pathogens, stimulating plant growth and improving the conditions for removing these metals.