Application and comparison of two different intraspecific protoplast fusion methods in Trichoderma harzianum and their effect on &#946-glucosidase activity

In an attempt to construct superior Trichoderma harzianum isolates for improving β-glucosidase productivity, protoplast fusion technique was applied. After application of different mutagenic treatments, twenty mutants were chosen to be tested for their resistance or sensitivity against four antifungal agents. Out of them, four isolates were selected on the basis of their response to antifungal agents and their productivities of carboxymethylcellulase (CMCase) and β-glucosidase to be introduced into intraspecific protoplast fusion experiments using two different methods (PEG and electrofusion). Three crosses were carried out among the selected four isolates. Results showed that, the number of fusants obtained after electrofusion were more than those obtained after polyethylene glycol (PEG) method. In addition, high productivities of CMCase and β- glucosidase were obtained after electrofusion in the three crosses. The applied protoplast electrofusion method proved to be a good and effective method for obtaining T. harzianum fusants with higher productivity of β- glucosidase enzyme.Key words: Trichoderma, protoplast fusion, electroporation, β-glucosidase