Avaliação in vitro do potencial antifúngico do Trichoderma asperelloides contra o fungos Aspergillus sp.

Abstract

The Trichoderma genus is composed of cosmopolitan and ubiquitous fungi that act in decomposition, mycoparasitism, aid in the treatment of diseases and in stimulating growth in plants, and produce enzymes that have antifungal properties. Biological control is defined as the use of living organisms, known as antagonists, with the aim of reducing the presence of other organisms considered pathogenic. Trichoderma acts as biocontrol through mycoparasitism, competition with pathogens for physical space and nutrients, production of metabolites with antimicrobial function and production of lytic enzymes. The Aspergillus genus is composed of cosmopolitan, ubiquitous and saprophytic fungi. They act in the processes of decomposition, bioremediation and are used in the food and pharmaceutical industries. They produce mycotoxins, which are secondary metabolites characterized by being toxic to humans and animals and being present in the natural environment. In addition, they can cause an opportunistic mycosis of recurrent cause, called aspergillosis, in which the form of infection is the inhalation of spores. The clinical manifestations are varied. The main objective of this study was to understand the antifungal potential of the fungus Trichodermaasperelloides against the fungus Aspergillus sp. through in vitro antagonism assays. Plates containing PDA medium were prepared for the maintenance of the fungus Trichoderma asperelloides. The fungus Aspergillus sp. was isolated from soil samples, which were cultivated in PDA médium + Tween 80 + chloramphenicol. The in vitro antagonism assays were performed in PDA medium with chloramphenicol, in which, in a 90 x 15 mm Petri dish, a 5 mm Trichoderma disk and a 5 mm Aspergillus disk were placed in the culture medium, with a distance of 4 cm between the two disks, and a distance of 2.5 cm between the edges of the plate. First, Trichoderma was inoculated and, after 12 hours, the fungus Aspergillus was added to the plate. The samples were placed in an incubator at 27°C ± 1°C, where they were observed and analyzed for 6 non-consecutive days. The percentage of inhibition of mycelial growth of Aspergillus was calculated according to the formula of Edgington (1971). The results showed that, in the antagonism tests, Trichoderma asperelloides was able to inhibit the growth of Aspergillus sp., presenting a greater mycelial growth over the days when compared to the pathogen. It was also observed that the percentages of inhibition of mycelial growth of Aspergillus sp. increased over the days, presenting an average value of 57%. It is concluded that the biocontrol Trichoderma asperelloides acted as an antagonist when confronted with Aspergillus sp.