Extraction,Purification,Physico-chemical Characteristic And Antifungal Activity Of Antibiotics Of Chaetomium Spirale ND35

Chaetomium Kunze ex Fr., which is one of the major genera of ascomycetes in the soil and substrate containing cellulose, distributes widely in nature. Some species of Chaetomium are potential antagonists of several plant pathogenic fungi. Chaetomium spirale ND35 is a strain of dominant endophytic fungus isolated from Populus tomentosa and displayed antagonistic activities against several common fruit and forest pathogentic fungi, such as Valsa. sordida , V. mail and R. solani, etc. One typical mode of action is that the Chaetomium spirale ND35 is able to produce antibiotic, it might play very important role in biocontrol of these diseases described above by C. spirale ND35.In this study, production, extraction and purification of the antibiotics produced by C. spirale ND35, as well as the antifungal activity in vitro, the stability and security-appraising of antibiotics, the control efficacy curvularia leaf spot of maize,bean gray mold,chestnut blight in greenhouse, regulation of antibiotics by different carbon and nitrogen source etc. were systemically investigated, in order to explore the mechanism of antibiotics produced by C. spirale ND35 involved in biocontrol activity. The major results are as follows:1. The culture filtrate of the strain ND35 was extracted by ethyl acetate, concentrated, and the brown crude extracts were obtained. Bioassay of antifungal activities showed that the crude extracts significantly suppressed mycelial growth of V. sordida etc. more than 20 kinds of phytopathogenic fungi in vitro experiments. Two active fractions were purified and mensurated by TLC and HPLC analyses.2. Yield of the crude extracts produced by C. spirale ND35 in PDB reached to the maximum after incubation for 15 days. The antifungal activities of antibiotics was not changed after dealed with the antibiotics under 121℃and 100℃. The suppression percentage of mycelial growth reached to 66.3% and 65.7% respectively. However, the suppression percentage of control reached to 65.56%. The antibiotics was stable in the condition of acidity but not stable in alkali condition.3. In laboratory and greenhouse experiments, the control efficacy of curvularia leaf spot of maize and bean gray mold reached 63.3% and 32.43% with antibiotics extract in 400μg/ml dilution. And the control efficacy of chestnut blight reached 46.29% with 1000μg/ml dilution. In addition the antibiotics treated on roots of bean were able to induce systemic resistance to Botrytis cineara caused bean gray mold,the control efficacy reached 71.39%.4. The potato dextrose broth (PDB) was the optimal culture medium by means of the screen of different culture medium; saccharose is the optimal carbon source; and then the ferment culture conditions were optimized by the experiments described above .5. The antibiotics had abilities to promote the growth of cucumber,bean and maize. It provided basis for the application of antibiotics in the future.