Separation And Identification Of The Soil Actinomycetes In BaYanNaoEr Region, Inner Mongolia, And The Study Of Their Resistance For Two Main Pathogens Of Potato

Actinomycetes is the main source of antibiotics.70% of antibiotics are isolated from actinomycetes. As estimated, the actinomycetes found until now are less than 1% of the total amount. Using antagonic substanced from actinomycetes to prevent plant diseases has got significant effects.In this study actinomycetes were isolated from different soil samples in Bayannaoer region, Inner Mongolia. Using phytophthora infestans and fusarium oxysporum as tested strains, the isolated actinomycetes strains were screened, and got antagonic strains with strong resistance to the two pathogens. The morphological, physiological, and biochemical characteristics were also studied.The results are as follows:(1) 179 strains with typical actinomycete characteristics were isolated from 25 soil samples in Bayannaoer region Among which, amount of strains from Xinji sample was the most,34 strains, accounting for 19% of the total.(2) Using pair culture method,136 strains with antagonistic activity against phytophthora infestans were obtained, and 96 strains have more than 10mm inhibiting diameter,40 strains have more than 20mm inhibiting diameter.91 strains with antagonistic activity against fusarium oxysporum were obtained, and 71 strains have more than 10mm inhibiting diameter,20 strains have more than 20mm inhibiting diameter. BY25, BY31, BY41, BY50, BY62, BY84, BY104, BY113, BY 117, and BY134strains are resistant to both pathogens. BY104 has the most resistance to phytophthora infestans and fusarium oxysporum, the inhibiting diameter reachs 25.7mm. BY104 has the most resistance to phytophthora infestans, the inhibiting diameter reachs 25.7mm and 27.3mm, respectively.(3) The anti-fungi activities of fermentation broth from BY104 and BY117 strains were tested with Oxford cup method and disc diffusion method. The results show that the fermentation broth from both strains have resistance to phytophthora infestans.(4) The morphologic, physiological and biochemical characteristics, as well as the 16SrDNA identification results show that BY25, BY84, BY104, BY113, and BY117 strains are Streptomyces.