Study On Diversity And Antibiotic Activity Of Endophytic And Rhizospheric Actinomycetes From Medicinal Plants In Panxi Region

Traditional Chinese medicinal plants are sources of biologically active compounds, providing raw material for pharmaceutical, cosmetic and fragrance industries. The endophytes of medicinal plants participate in biochemical pathways and produce analogous or novel bioactive compounds. Panxi region in South-west Sichuan in China with its unique geographical and climatological characteristics is a habitat of a great variety of medicinal plants. In this study,560 endophytic actinomycetes were isolated from 26 medicinal plant species in Panxi region.60 isolates were selected for 16S rDNA-RFLP analysis, and 14 representative strains were chosen for 16S rDNA sequencing. According to the phylogenetic analysis, seven isolates were Streptomyces sp., while the remainder belonged to genera Micromonospora, Oerskovia, Nonomuraea, Promicromonospora and Rhodococcus. Antimicrobial activity analysis combined with the results of amplifying genes coding for polyketide synthetase (PKS-â… . PKS-â…¡) and nonribosomal peptide synthetase (NRPS) showed that endophytic actinomycetes isolated from medicinal plants in Panxi region had broad-spectrum antimicrobial activity and potential natural product diversity, which further proved that endophytic actinomycetes are valuable reservoirs of novel bioactive compounds.Root is pharmaceutical parts for most of chinese medicinal plants that imply active ingredients of medicinal plant were usually accumulated in root, the microorganism that were existed in rhizosphere of medicinal plants probably produce more antibiotic substance than the microbiota of bulk soils.196 actinomycetes strains were isolated from rhizosphere of medicinal plants by using 4 isolated methodes and 7 selective media, and those isolates were divided into 12 clusters. Based on morphological characteristics of strains,50 representative isolates were selected. According to the phylogenetic analysis, these isolateds were belonged to genera Streptomyces, Micromonospora, Nonomuraea, Oerskovia, Actinoplanes, Nocardioides, Amycolatopsis. Rhodococcus, Promicromonospora, Cellulomonas, Micrococcus, Arthrobacter, Saccharopolyspora, Mycobacterium, respectively, Streptomyces was the dominant genera. In the antimicrobial activity screening test, most of the isolates belonged to genera Streptomyces which showed antogonistic activity against 11 indicator organisms.We investigated the diversity of the uncultured actinomycetes from 7 medicinal plants by PCR-DGGE technique, analysed the relationship between rhizospheric actinomycetes community from differnet medicinal plants. The results revealed that the distribution of rhizosphere actinomycetes were influented by different medicinal plants, even though they located in the same ecological environment. Based on the result of isolation and PCR-DGGE profiles, the rhizosphere actinomycets 16S rDNA gene library of medicinal plant Ainsliaea henryi were constructed. Biodiversity were analyzed by amplified rDNA restriction analysis, DNA sequencing and phylogenetic analysis. The result showed 50 clones were separated into 31 OTUs, and 53.1% of the clone sequences belonged to 4 subclasss,5 suborders,5 families,6 genus of actinomycetes; the remainders belonged to unidentified actinomycetes which indcated medicinal plant from Panxi region possessed abundant diversity.In this study, the rhizospheric actinomycetes diversity of medicinal plants were investigated by using cultured-and uncultured protocols, which will help to study and utilized the actinomycetes resources of medicinal plants in Panxi region.