Regulation of chitinase synthesis in Trichoderma harzianum

The production of chitinase by Trichoderma species is of interest in relation to their use in biocontrol and as a source of mycolytic enzymes. Fourteen isolates of the genus were screened to identify the most effective producer of chitinase. The best strain for chitinase was Trichoderma harzianum 39.1, and this was selected for study of the regulation of enzyme synthesis. Washed mycelium of T. harzianum 39.1 was incubated with a range of carbon sources. Chitinase synthesis was induced on chitin-containing medium, but repressed by glucose and N-acetylglucosamine. Production of the enzyme was optimal at a chitin concentration of 0.5%, at 28 degrees C, pH 6.0 and was independent of the age of the mycelium. The synthesis of chitinase was blocked by both 8-hydroxyquinoline and cycloheximide, inhibitors of RNA and protein synthesis, respectively. The mode of chitinase synthesis in this fungus is discussed.