Colony growth, in vitro antagonism and secretion of extracellular enzymes in cold-tolerant strains of Trichoderma species

Of three hundred and sixty Trichoderma strains investigated, fourteen, identified as T. aureoviride, T. harzianum and T. viride, grew well at 5 degrees C on both minimal and yeast extract agar media. In dual culture tests at 10 degrees, most strains antagonized the phytopathogens Rhizoctonia solani and Fusarium oxysporum f. sp. dianthi. T aureoviride and T. viride were more effective against Pythium debaryanum than T. harzianum. The activities of extracellular chitinases (EC 3.2.1.30), beta-glucosidases (EC 3.2.1.21) and proteases (EC 3.4.21.1; EC 3.4.21.4), which are thought to be involved in the mycoparasitic process, were also examined and results showed that these enzymes were highly active at 5 degrees in the cold-tolerant strains.