Induction of secretion of extracellular proteases from Trichoderma viride
Department of Biochemistry and Microbiology, Institute of Biochemistry, Nutrition and Health Protection, Faculty of Chemical and Food Technology, SUT, Radlinského 9, 812 37 Bratislava, Slovakia
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Abstract: Filamentous fungi possess an efficient hydrolytic system capable of utilize the wide spectrum of complex substrates. Cellulolytic enzyme systems produced by the different strains of Trichoderma spp. are the best examples of versatility and adaptability for the saprophytic strategy of surviving. Filamentous fungi are known to secrete serine-, aspartic- and metallo- proteases upon cultivation. In this study we aimed to answer the question whether the secretion of protease(s) in filamentous fungi is dependent on the type of protein used as substrate. We found that the secretion of protease(s) by Trichoderma viride is induced in the presence of yeast extract, or of purified proteins, such as bovine serum albumin, casein, or ovalbumin. We found furthermore that properties of proteases induced under cultivation conditions were different in various aspects (temperature- and pH-dependencies, substrate specificity, sensitivity to protease inhibitors, chromatographic properties). Protease activities were characterized by electrophoresis in polyacrylamide gel with co-polymerized gelatin. Multiple proteases bands with high-molecular weights (higher than 70 kDa) were detected by gelatin zymography. Patterns of protease bands were inducer-specific.
These results show that the induction of extracellular proteases in Trichoderma viride fungus is not purely nutritive process but it also includes an unknown molecular recognition process, which triggers a specific secretory response.
Keywords: secretion of proteases, Trichoderma viride
Full paper in Portable Document Format: acs_0022.pdf
Acta Chimica Slovaca, Vol. 1, No. 1, 2008, pp. 250—264