Isolation and characterization of protease overproducing mutants of Trichoderma harzianum

Several Trichoderma strains have been reported to be effective in controlling plant diseases, and the action of fungal hydrolytic enzymes is considered as the main mechanism involved in the antagonistic process. Strain Trichoderma harzianum T334 is a potential biocontrol agent against plant pathogen...

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Bibliographic Details
Published in:FEMS microbiology letters 2004-04, Vol.233 (2), p.215-222
Main Authors: Szekeres, András, Kredics, László, Antal, Zsuzsanna, Kevei, Ferenc, Manczinger, László
Format: Article
Language:English
Subjects:
Altered colony morphology
Biological and medical sciences
Endopeptidases - genetics
Fundamental and applied biological sciences. Psychology
Gene Expression Regulation, Enzymologic
Gene Expression Regulation, Fungal
Genetic Testing - methods
Genetics
Microbiology
Miscellaneous
Mutagenesis
Mycology
p-Fluorophenyl-alanine resistance
Plants - microbiology
Protease overproduction
Trichoderma - enzymology
Trichoderma - genetics
Trichoderma harzianum
UV-mutagenesis
Virology
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Summary:Several Trichoderma strains have been reported to be effective in controlling plant diseases, and the action of fungal hydrolytic enzymes is considered as the main mechanism involved in the antagonistic process. Strain Trichoderma harzianum T334 is a potential biocontrol agent against plant pathogenic fungi with the ability to produce low levels of proteases constitutively. To improve its fungal antagonistic capacity, mutagenetic program was undertaken for the construction of protease overproducing derivates. The mutant strains were obtained by means of UV-irradiation and were selected for p-fluorophenyl-alanine resistance or altered colony morphology. It was revealed by means of specific chromogenic protease substrates that both trypsin-like and chymotrypsin-like protease secretion was elevated in most of the mutant strains. The profiles of isoenzymes were different between the mutants and the wild-type strain, when examined by gel filtration chromatography. Certain mutants proved to be better antagonists against plant pathogens in in vitro antagonism experiments. This study suggests the possibility of using mutants with improved constitutive extracellular protease secretion against plant pathogenic fungi.
ISSN:0378-1097
1574-6968
DOI:10.1016/j.femsle.2004.02.012