Seleção de fungos do bioma Caatinga com maior potencial para a produção de quitosanase.

Abstract

The objective of this study was to identify and select fungal isolates of the Caatinga with the greatest potential for the production of chitosanase as well as to assess the efficiency of the method of selection employed by the estimation of genetic, environmental variation coefficients and heritability in the broad sense. The experiments were performed in the Biology Laboratory (BIOLAB) and Plant Health Laboratory Semi-Arid (LAFISA), located at the Center for the Semi-Arid Sustainable Development of the Federal University of Campina Grande (CDSA / UFCG). This study used 117 fungal isolates belonging to the "Fungi Caatinga Collection (FCC)". The experimental design was a completely randomized design with three replications. The treatments were 30 fungal isolates that developed in selective medium containing chitosan. The response variable used was the enzymatic index (EI). The data relating to enzymatic index were subjected to analysis of variance, with the SAS computational package resources. The treatment means were compared by the Scott-Knott test at 5% probability. Among the 117 isolated fungal isolates only 53 (45.30%) showed growth profile in culture medium containing chitosan as the sole carbon source and inducer for the production of chitosanase. Of the 53 fungal isolates obtained in the pre-selection, we identified 30 isolates to be analyzed using the analytical method for the production of chitosanase. The relationship between the estimated coefficient of genetic variation, environmental and heritability showed high ratio, demonstrating the efficiency of the method used for the selection of genotypes. There is great genetic variability among 30 genotypes for the studied characteristic (production of chitosanase enzyme). The coefficients of genetic variation (CVg), heritability in the broad sense ( 2 a h ) and the ratio b = CVg / CVe indicate a favorable situation for the selection of genotypes in characteristic analyzed. Seventeen genotypes were selected to undergo further stages of the breeding program as promising for the production of the enzyme chitosanase; that is, they showed an enzymatic index greater or equal to two.