Abstract
Trichoderma enzymes that inhibit fungal cell walls have been suggested to play an important role in mycoparasitic action against fungal root rot pathogen Ganoderma philippii . This experiment was aimed to purify and characterize the â-1,3-glucanase of T. reesei . Extracellular â-1,3-glucanase was produced by growing mycoparasite T. reesei isolate T 13 in colloidal chitin and sucrose as carbon sources. The enzyme was then purified to its homogeneity by precipitation with ammonium sulfate, followed by gel filtration chromatography and chromatofocusing. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) 12% was used to confirm the purity of enzyme at each stage of preparation and to characterize purified protein. The results showed that T. reesei produced at least three extracellular â-1,3-glucanases. Estimation of molecular weight based on SDS-PAGE 12% have three isoform of â-1,3-glucanase were 90 kDa for â-1,3-glucanase-I, 75 kDa for â-1,3-glucanase-II, and 64 kDa for â-1,3-glucanase-III. Their optimum pH and temperature were 5 and 50 °C, respectively.
Highlights
Biological control by antagonistic organisms is a potential nonchemical tool for crop protection against phytopathogenic fungi (Papavizas 1985)
Glucans and chitin are the major constituents of fungal cell walls, and the important roles of glucanolytic and chitinolytic enzymes in the degradationof fungal cell walls during mycoparasitism by Trichoderma have previously suggested (Lorito et al 1994)
The mycoparasitic action of Trichoderma has been proposed as the major mechanism for their antagonistic activity against phytopathogenic fungi
Summary
Biological control by antagonistic organisms is a potential nonchemical tool for crop protection against phytopathogenic fungi (Papavizas 1985). Several strains of the genus Trichoderma have been described as antagonistic fungi to control a wide range of phytopathogenic fungi. The antifungal activity of Trichoderma involves in production of antibiotics, competition for key nutrients, and production of fungal cell wall-degrading enzymes (Hjeljord & Tronsmo 1998). Mycoparasitism by cell wall-degrading enzymes have been proposed as the major mechanism of Trichoderma antagonistic activity against fungal plant pathogens (Chet et al 1998). The mycoparasite grows directly towards its host and often coils arround it or attaches to it by forming hook-like structures and apressoria. Following these interactions, Trichoderma spp. sometimes penetrate the host miselium, apparently by partially degrading its cell walls. It is assumed that Trichoderma spp. utilize intracellular contents of the host (De La Cruz et al 1995a)
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