Study On The Isolation, Identification And Bioactivity Of Endophytic Actinomycetes From Medicinal Plants In Western Sichuan Plateau

Actinomycete is an important microbiological resource which can produce lots of bio-control agents such as antibacterial agents, enzymes and enzyme preparations, antivirus and antitumor activities. By now, plenty of antibiotics were found, people need to explore a new way to find new antibiotics. As a result of long-held symbiotic relationship between endophytic microbes and plants, endophyte may have unique genetic and biological system. Medical plants represent a rich and relatively unexplored source of endophytic actinomycetes, from the secondary metabolites of endophytic actinomycetes, many compounds with new structures and huge bioactive diversities could be found. Several reports indicated that endophytic actinomycetes seems to have great potential in medical, agricultural, environmental and industrial fields.In this study, the endophytic actinomycetes were isolated from 10 medical plants collected from Western Sichuan Plateau. Four selective culture media and nine carbon resources were chosen. As a result,214 isolates of endophytic actinomycetes were obtained. Different experimental materials on the endophytic actinomycetes obtained in quantity is quite different. The isolation effect of different media are mixed ragged. The result indicated that modified Gause II medium and HVA medium are best for isolation in this experiment. The proper inhibitor combination: 50μl/ml potassium dichromate and 100μl/ml cycloheximide.Fifty representative isolates were tested for antifungal activities from three kinds of plant pathogens. The results indicated that most of isolates have antifungal activities.Forty strains inhibited at least one of the plant pathogens tested. Seventeen strains inhibited two plant pathogens. Strain Y3101 and Strain Y3104 inhibited three plant pathogens used in this experiment. They were both isolated from Salvia officinalis. The result suggested that the endophytic actinomycetes of medicinal plant were potential inhibitor for plant pathogen, it can be a new source of novel bioactive compounds.sAccording to morphology and culture properties, the result showed that most of the isolates were streptomycete strains. Fourteen strains were chosen for 16S rDNA sequences analysis, then reconstruct phylogeny tree. Based on the result of morphological and molecular identification, taxonomic status of these strains were preliminarily determined.The isolates Y3056,Y3057,Y3066,Y3069,Y3078,Y3087,Y3095,Y3099,Y3101,Y3103,Y3104,Y3106 were identified as Streptomyces niger, Streptomyces pluricolorescens, Streptomyces coelicolor, Streptomyces sampsonii, Streptomyces odorifer, Streptomyces rochei, Streptomyces microflavus, Streptomyces anulatus, Streptomyces limosus, Streptomyces plicatus, Streptomyces fungicidicus, Streptomyces albidoflavus, Streptomyces arenae, Streptomyces exfoliates, respectively.