Szekeres András, Kredics László, Antal Zsuzsanna, Kevei Ferenc, Manczinger László
Department of Microbiology, University of Szeged, P.O. Box 533, H-6701 Szeged, Hungary.
FEMS Microbiol Lett. 2004 Apr 15;233(2):215-22. doi: 10.1016/j.femsle.2004.02.012.
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.
据报道，几种木霉菌株在控制植物病害方面有效，并且真菌水解酶的作用被认为是拮抗过程中的主要机制。哈茨木霉菌株T334是一种潜在的针对植物病原真菌的生物防治剂，具有组成型产生低水平蛋白酶的能力。为了提高其真菌拮抗能力，开展了诱变程序以构建蛋白酶高产衍生物。通过紫外线照射获得突变菌株，并选择对对氟苯丙氨酸具有抗性或菌落形态改变的菌株。通过特异性显色蛋白酶底物发现，大多数突变菌株中类胰蛋白酶和类胰凝乳蛋白酶的分泌均增加。通过凝胶过滤色谱法检测时，突变体和野生型菌株之间的同工酶谱不同。在体外拮抗实验中，某些突变体被证明是针对植物病原体的更好拮抗剂。本研究表明，有可能使用组成型细胞外蛋白酶分泌得到改善的突变体来对抗植物病原真菌。
