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Study of enzymes secreted by oomycete Pythium oligandrum
Hrdinová, Karolína ; Ryšlavá, Helena (advisor) ; Kubíčková, Božena (referee)
Pythium oligandrum is one of the non-pathogenic microorganisms of Pythium species which found its use as biological control agent. The main modes of action of this oomycete lie in inducing the plant immunity and in mycoparasitism of pathogenic fungi and fungus-like organisms. The oomycete attacks the pathogens by secretion of hydrolytic enzymes into the environment. In the first part of this bachelor's thesis, activity of hydrolytic enzymes endo-1,3-β-glucanase, cellulase, chitinase and proteases was observed in a commercial product based on Pythium oligandrum, called Polyversum-Biogarden. It was conclu- ded that the direct hydrolysis of phytopathogens is probably not the main mechanism of this product because the activity of glycosidases increased only after six hour-long incubation of the Polyversum-Biogarden in water and the proteolytic activity was not detected. In the second part of the bachelor's thesis, properties of proteases secreted by orga- nism Pythium oligandrum were studied. The highest proteolytic activity was observed at pH 6,5. Ovomucoid acted as an inhibitor of secreted proteases. The stability of pro- teases was lowered by SDS, detergents present in liquid soaps and by a solution of a solid soap or NaOH. Only the highest concentrations of urea lowered the activity of proteases....
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