Resumo

The fungus Metarhizium anisopliae is considered an efficient agent for the biological control of insects, possessing various factors of virulence, including the production of proteases considered essential in the process of penetration through the insect’s cuticle. This work presents the proteolytic activity from an isolate of M. anisopliae, using noncuticular substrate to ascertain their influence on the expression of this enzyme. We used an isolate of M. anisopliae collected soil of an agroforestry system in the forest zone of Pernambuco. For the macroscopic analysis, we used the culture medium Sabouraud-dextrose-agar. The behavior was evaluated by measuring the diameter of the colony for 15 days of growth. Then the arithmetic average was calculated for the construction of the growth curve. The enzymatic activity was determined from the Enzymatic Index (EI) in Minimum Medium (MM) without glucose, with the addition of casein (milk Molico®). The degradation was evaluated macroscopically by the formation of a transparent halo around the colony for 15 days of growth. An experiment was conducted with three replications. The radial growth evaluated for 15 days on Sabouraud-dextrose-agar, reached 2.5 cm. The colony showed a whitish pigmentation with a mass of green conidia. These results indicate that the culture medium was efficient for inducing the growth and sporulation of M. anisopliae in vitro. The proteolytic activity of M. anisopliae was detected by the formation of transparent halo around the colony, measuring 0.2 cm. The halo was formed by the breakdown of milk casein Molico®, the sole source of nitrogen added to the culture medium. Morphologically, the colony showed whitish mycelium with high production of conidia of green coloration, characteristic of the species. M. anisopliae presented IE 0.97 confirming that the isolated enzyme activity has a positive (IE = 0.64 <1, Pz = 2). The results for the production of noncuticular protease allow a preliminary evaluation of the amount of protease secreted by this isolate. This will be isolated subsequently analyzed for production of specific proteases, such as Pr1 and Pr2, and studies such as this will allow a better understanding of possible factors that may affect the efficiency of this isolated in the biological control of certain insects.