Isolation Of Soil Actinomycetes From The Region Of Wuhai,Inner Mongolia And The Study On The Antagonism Of Actinomycets Against The Three Pathogenic Fungi Of Potato

Actinomyces can produce bio-active substances, such as antibiotics, inhibitors, and enzymes, and have great economic value. More than two-thirds bioactive substances are produced by actinomyces, therefore they have great significances for bio-control research. There are plenty of actinomycetes in soil, so the research and application of soil actinomycetes are of great significance. Potato (Solarium tuberosum L.) is one of the four major food crops in the world and is already the main food crop in Inner Mongolia. However, it has been threatened by a variety of fungi diseases, among which, potato late blight, potato blight, and potato black scurf are relatively the most serious, resulting in a decline in yield and quality. Using chemical pesticide to prevent plant fungi can not only pollute the environment, cause drug-resistance, but also threat to human health. Biocontrol can avoid the above problems. Therefore, using various microorganisms to prevent plant diseases has become more and more popular.In this study, three kinds of potato pathogen were regarded as the target bacteria, and antagonistic actinomycetes are separated from soil in Wuhai region, Inner Mongolia. Their antagonistic characteristics and the anti-fungi activities of their extracellular and intracellular metabolites against the three potato pathogens were studied. Our research will laid foundation for obtaining environment-friendly microbial pesticide. The main results are as follows:1.110 strains with typical characteristics of actinomycetes were separated from 14 soil samples in Wuhai region, Inner Mongolia.2. Using pair culture method,37 strains with antagonistic activity against phytophthora infestans were obtained, and 12 strains have strong resistance. The antagonistic activity of these 12 strains against fusarium oxysporum and Rhizoctonia solani were tested and found 8 strains have resistance to fusarium oxysporum,8 strains have resistance to rhizoctonia solani. There are 7 strains can be resistant to the three pathogens above.3.8 strains of antagonistic actinomycetes were tested for the anti-fungi activities of the intracellular and extracellular metabolites against phytophthora infestans. The results showed that all the 8 strains had anti-fungi activities.4. The colonization experiment of WH29 in potato root showed that in the tenth week of potato growth, the amount of the inoculated actinomycete was 105 cfu/mL, which indicates that WH29 can colonize in potato root.5.12 strains of antagonistic actinomycetes were screened to observe the colony characteristics, culture characteristics, and 16S rDNA molecular identification. Among which, WH29 and WH58 have the highest consistency with streptomyces silaceus and the consistency rate is 98.82% and 99.06%, respectively.