Isolation And Identification Of Myxobacteria From Hohhot And Analysis Of Active Substances Against Potato Late Blight Pathogen

Microbial pesticides are an important part of biological pesticides, and in recent years we have made tremendous development in this field. Myxobacteria are a rich source producing secondary metabolites. Isolation and identification of myxobacteria can not only enrich the myxobacterial resource but also provide the material guarantee for the development of new drugs.In this study,73strains were isolated from the samples collected from the Hohhot region of Inner Mongolia by rabbit dung pellets inducing method, filter inducing method, and E. coli inducing method and33of them were purified. The purified strains were identified by their fruting body and colony morphology, their physiological and biochemical characteristics, and16S rDNA method. It turned out that the strains belonged to Corallococcus、Archangium、Myxococcus、Cystobacter、Sorangium. Tests for antibiotic activity indicated that17strains had the activity against E. coli,18had the activity against Staphylococcus aureus,17had the activity against Saccharomyces cerevisiae,22showed the activity against Bacillus subtilis,27exhibited different degree of resistance to the pathogen of potato late blight, Phytophthora infestanse, and6of which had higher activity against Phytophthora infestanse.The active substances of the strain Xt-2with a high resistance to Phytophthora infestanse were analyzed preliminarily. It turned out that the active substances of the strain Xt-2mainly existed in the extracellular metabolites. The active substances were not protein and tolerant to UV light, but sensitive to the high temperature, too acidic or too basic environment. After liquid culture, the medium was collected to isolate and identify the active substances by silica gel column chromatography, dextran gel column chromatography, GC-MS, and LC-MS methods. The results showed that10main substances were identified,4of which were identified by LC-MS method, whose formula weight was246.1,264.1,282.1, and563.3, and6of which were identified by GC-MS method, including C8H,4O, C8H,4O, C8H13NO2. C14H20O3, C15H24O, C17H22O5, whose formula weight was126.1,126.1,155.1,236.1,220.2, and306.1.This study has a contribution to enriching the myxobacterial resource in Inner Mongolia and will lay a foundation for the further study on myxobacteria and the development of new drugs against potato late blight.