Induction, Purification And Antifungal Activity Of β-1,3-glucanases Related To Mycoparasitism Of Chaetomium Spirale ND35

Chaetomium Kunze ex Fr., which is one of the major genera ofascomycetes in the soil and substance containing cellulose, distributes widelyin nature. Some species of Chaetomium are potential antagonists of severalplant pathogenic fungi. Chaetomium spirale ND35 is a strain of dominantendophytic fungus isolated from Populus tomentosa and displayedantagonistic activities against several common fruit and forest pathogenticfungi, such as Cytospora chrysosperma, V. mail and R. solani, etc. Severalmodes of action such as antibiosis and production of extracellular lyticenzymes, mainly chitinases and β-1,3-glucanases responsible for myco-parasitism of this antagonist might play very important role in biocontrol ofthese diseases described above by C. spirale ND35. In addition, the biocontroltrials under green-house and field conditions have proved the biocontrolpotential of strain ND35 against V. mali, the causal agent of apple canker.In this study, induction and regulation of β-1,3-glucanases fromendophytic fungus Chaetomium spirale ND35 by different carbon source, aswell as purification, properties and antifungal activity of β-1,3-glucanase werereported. Further TEM ultrastructural investigation on interaction between C.spirale ND35 and R. solani by immuno-cytochemical labeling was carried outin order to get better understanding about the role of β-1,3-glucanase played inmycoparasitism. The major results are as follows:1. Cell wall preparation(CWP) of several fungi including Valsa sordida,Saccharomyces cerevisiae, R. cereali and R. solani, as well as polysaccharidessuch as colloidal chitin and laminarin can induce β-1,3-glucanases by C.spirale ND35. The laminarin was the optimal carbon source. However, highlevel of glucose as catabolite repressed the production of β-1,3-glucanases.2. At least two β-1,3-glucanases and a chitinase were produced byendophytic fungus Chaetomium spirale ND35 when it was grown in Syntheticmedium(SM) supplemented with the cell wall preparation(CWP) of phyto-pathogenic fungus, Rhizoctonia solani as inducer, simulating natural myco-parasitism. An endo-β-1,3-glucanase GLUC73 was purified to electrophoretichomogeneity through using 80% ammonium sulfate precipitation and DEAESepharose Fast Flow anion-exchange chromatography, followed by PhenylSepharose Fast Flow hydrophobic chromatography. Purification folds andyield were 18.54 and 3.84%, respectively. The molecular mass was estimated...