Regulation of β-1,3-glucanase by carbon starvation in the mycoparasite Trichoderma harzianum

The β-1,3-glucanase system of the mycoparasitic T. harzianum, isolate T-Y, was found to be composed of at least five different enzymes. Their migration distance in acrylamide gels corresponded to peptides with molecular masses of 30-200 kDa, and they were named accordingly. The largest enzyme - Gβ-1,3-200, was the most abundant when T-Y was grown with no carbon source. Its secretion was almost eliminated when T-Y was grown on media containing a high concentration of carbon sources such as N-acetylglucosamine (GlcNAc) or malic acid. Several isolates of T. harzianum were found to have a β-1,3-glucanase secretion system, controlled by catabolite repression. Each isolate exhibited a different β-1,3-glucanase profile Gβ-1,3-200 was isolated and purified its molecular mass was approximately 75 kDa, and its activity was of the exo-type, specific to β-1,3-glucan linkages. Four short peptides resulting from proteolysis of this enzyme were sequenced, and their sequences were most homologous to LAM13, a previously isolated β-1,3-glucanase.