Produção e caracterização de enzimas quitinolíticas produzidas pelo fungo Trichoderma asperellum e sua aplicação no biocontrole do carrapato Rhipicephalus microplus e do inseto Aedes aegypti
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2020-03-02
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Universidade Federal de Goiás
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Chemical acaricides or insecticides are widely used to control pests or vectors of agricultural interest and public health worldwide. The molecules on the market have an average duration of a decade due to the genetic selection of resistant individuals. In addition, these chemical compounds can affect other living organisms, contributing to environmental pollution and contamination of products of animal or vegetable origin for human consumption. With options for chemical control of pests and parasites increasingly scarce, studies are described stimulating the search for alternative and effective control methods. The use of living organisms or products of their metabolism to control pests or diseases, whether obtained by genetic manipulation or not, are called biocontrol. Several studies demonstrate the use of fungi as alternative or auxiliary agents for vector control, with low environmental impact, easy application and degradation. As an example of these microorganisms, the fungus Trichoderma asperellum stands out. The genus Trichoderma corresponds to free-living fungi, mostly of asexual reproduction, found from temperate to tropical climates. These fungi are known for their capacity as biological control agents, against phytopathogens. This action can occur by the release of enzymes or other secondary metabolites. The objective of this work was to evaluate the potential use of the fungus Trichoderma asperellum grown on different carbon sources (commercial chitin (CWDE), external chitinous tegument of the tick Rhipicephalus microplus (T-CWDE) and Aedes aegypti (L-CWDE) larvae) , as an agent producing enzymes of the chitinylitic complex, for the biocontrol of the vectors Rhipicephalus microplus and Aedes aegypti. The fungus was grown in MEA medium and the spores, together with different chitinous sources, were added to the TLE medium and incubated for six days at a temperature of 38ºC. The crude extract, resulting from the induction by carbon sources, after undergoing the process of dialysis and lyophilization, was used to perform the biocarrapaticidogram and larvicide tests. The results showed that the T-CWDE and L-CWDE media showed greater activity against both the tick larvae Rhipicephalus microplus and L3 of Aedes aegypti compared to CWDE. The enzymatic action in the target vectors was also evidenced by scanning electron microscopy (SEM) and transmission electron microscopy (MET), suggesting that the biotechnological strategy proposed in this work has the potential to be explored for the biocontrol of these vectors, given their viability and the likely benefits such as the generation of natural bioactive and biodegradable compounds compared to conventional pesticides.
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AGUIAR, J. P. S. A. Produção e caracterização de enzimas quitinolíticas produzidas pelo fungo Trichoderma asperellum e sua aplicação no biocontrole do carrapato Rhipicephalus microplus e do inseto Aedes aegypti. 2020. 65 f. Dissertação (Mestrado em Ciência Animal) - Universidade Federal de Goiás, Goiânia, 2020.