Abstract: In order to explore the resource diversity and microbial inhibition activity of bacterial endophytes from endangered medicinal plant Ammopiptanthus mongolicus, the bacterial endophytes were isolated from root,stem and leaf of the host by tissue homogenization or grinding method and five pathogenic fungi and four bacterial strains were used as indicators to test microbial inhibition activity by agar plate antagonistic action,growth rate test and agar disc diffusion method.The results indicated that 32 bacterial endophytes were isolated from the host,most of them came from leaf,followed by root and stem.Based on morphological characters and Gram staining reaction,28 strains were G⁺,making up 87.5% of the total isolates;The preliminary screening for antagonistic activity to pathogens showed that 21 strains had antifungal activities against 2 or more pathogens at different levels,accounting for 65.6% of the total isolates and 2 strains of AMEBR007and AMEBR008 expressed evident antifungal activity to both Colletotrichum gloeosporioides and Gaeumannomyces graminis var.tritic,and the secondary screening for microbial inhibition activity by adoption of growth rate showed that the strain AMEBR007 had better microbial inhibition effect,the microbial inhibition rate was 31.26% to Colletotrichum gloeosporioides and 11.56% to Gaeumannomyces graminis var.tritic respectively;Based on agar disc diffusion method,some bioactive strains were selected for bacterial inhibition test,indicated AMEBR007 having evident antibacterial inhibition activities to Bacillus subtilis and Staphylococcus aureus.The endangered medicinal plant Ammopiptanthus mongolicus had relatively rich endophytic bacterial resource,and the strains of antimicrobial inhibition activities will be worthwhile for further studies.

Key words: medicinal plant, Ammopiptanthus mongolicus, bacterial endophytes, isolation, microbial inhibition activity