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

The beta-1,3-glucanase system of the mycoparasitic T. harzianum, isolate T- Y, was found to be composed of at least five different enzymes. Their migra tion distance in acrylamide gels corresponded to peptides with molecular ma sses of 30-200 kDa, and they were named accordingly. The largest enzyme - G beta-1,3-200, was the most abundant when T-Y was grown with no carbon sour ce. Its secret-ion was almost eliminated when T-Y was grown on media contai ning a high concentration of carbon sources such as N-acetylglucosamine (Gl cNAc) or malic acid. Several isolates of T. harzianum were found to have a beta-1,3-glucanase secretion system, controlled by catabolite repression. E ach isolate exhibited a different beta-1,3-glucanase profile. G beta-1,3-20 0 was isolated and purified: its molecular mass was approximately 75 kDa, a nd ifs activity was of the exo-type, specific to beta-1,3-glucan linkages. Four short peptides resulting from proteolysis of this enzyme were sequence d, and their sequences were most homologous to LAM1.3, a previously isolate d beta-1,3-glucanase.