CONICET | Buscador de Institutos y Recursos Humanos

Biological control is a promising alternative to regulate populations of pathogenic fungi responsible for various phytosanitary problems. The Trichoderma genus is widely used as a biocontrol agent due to its wide mycoparasitic capacity. Its main mechanism of action is the secretion of extracellular mycolytic enzymes, such as chitinases, β-1,3-glucanases, and proteases. The objective of the present work was to optimize the components of a liquid culture medium to enhance the mycolytic enzymatic activity of the Trichoderma koningiopsis POS7 strain, previously selected by our working group for presenting high biocontrol activity. Through the use of a response surface design (RSM), Box-Behnken, the effect of three concentrations of the yeast extract nitrogen source was tested: 0.2 g/l.; 1.1 g/l.; 2 g/l.; three initial inoculum concentrations: 2x10 7 spores/ml.; 1x10 7 spores/ml.; 1x10 6 spores/ml.; and three different pH´s of the culture medium: pH 7; pH 5.5; pH 4. Seventeen assays in liquid fermentation were carried out, with continuous stirring at 100 rpm at 28 ± 1 ºC for 12 days. A concentration of 7% of Fusarium sp. treated cell walls was used as a carbon source, which was previously selected for showing statistically significant and positive effects on the enzymatic secretion of chitinases, β-1,3 glucanases and proteases. To quantify protease activity, the azocasein method was used; and for the chitinases and β-1,3-glucanases activities, the dinitrosalicylic acid method was used and the results were analyzed using the statistical program Statgraphics centurion XVI. After the analysis of variance of RSM, a statistically significant positive effect was observed by the concentration of 0.2 g/l. of the nitrogen source (p

enviar mensaje