Antimicrobial Activity Of Endophytic Actinomycets And Isolation, Identification Of The Pathogen From Polygonum Cuspidatum

In recent years, the plant in particular the medicinal plant endophytic actinomycetes hasbecome the mainly producing strains of newtype antibiotics and also become many scholars’research hotspot. But as a result of the long growth cycle of and easy to be polluted, theisolation method and antimicrobial activity of endophytic actinomycetes are still the maincontent in the future.The material is Polygonurn cuspidatum that is characteristic Chinese traditionalmedicine from Qinba mountains. Screen and identify the isolation method, surfacedisinfection, sterilization time, media, bacteriostatic agent concentration, etc. Besides,studying on antimicrobial activity of isolated strains, and identified the strains with biologicalactivities preliminarily.Using the method of tissue homogenate to isolate polygonum cuspidatum endophyticactinomyces through some procedures like material pretreatment, surface disinfection, etc.Obtained47strains of endophytic actinomycetes with eliminate repetitive. Determinedadvantage medium: glucose as carbon source in the medium separating effect is best;Trehalose-proline medium can be used to separating relatively rare actinomycetes. Onsurface disinfection results of research show that in75%medical alcohol treatment for30s,after that in0.1%HgCl2treatment for5min, that’s good enough to kill the saprophyticbacteria on the sample surface of the polygonum cuspidatum, and no effect on theactinomycetes of the inner organization. It is concluded that when nystatin100.0mg/L,75.0mg/L potassium dichromate, nalidixic acid20.0mg/L after a test of bacteriostatic agentconcentration.This can effectively inhibit bacterial breeding, and not affect the growth ofactinomyces.A measurement of antimicrobial activity about47isolated Polygonum cuspidatumendogenous actinomyces strains show that, there are19strains actinomycetes revealed thebiological activity after preliminary screening, and5endophytic actinomycetes still showeddifferent degrees of antibacterial activity after re-screening and disturbance rejection. This suggests that the bacteriostatic activity of some actinomycete is unstable for follow-up study.Conclusion of the morphological classification and molecular biology identification: the5strains of endophytic actinomycetes are identified as Micromonospora (PEA003, PEA041),Streptomyces (PEA002),Streptosporangium(PEA023), Nocardiopsis (PEA017) preliminarily.Above these showed species diversity of Polygonum cuspidatum endogenous actinomyces.The strain of PEA023that classed to Streptosporangium showed better antagonism tocommon target bacteria and one target fungi during the preliminary screen and re-screen. So ithas great potential as antibiotic strain.By the method of normal tissue homogenate, separate and identify pathogens whichcausing root rot disease of Polygonurn cuspidatum. Then take the plants artificial infectiontest by two different method of dipping root and acupuncturing root respectively, re-separatepathogen, and determine that the P051is a strain of pathogen. After morphological andmolecular biology identification and a series of physiological and biochemical reaction suchas contact enzyme, oxidase, glucose, lactose, mannitol, gelatin liquefaction, nitrate reductionetc, the strain of P051be finally considered as Micrococcaceae, Micrococcus, Micrococcusluteus.