– 942 – Chinese Journal of Natural Medicines 2015, 13(12): 09420953 doi: 10.3724/SP.J.1009.2015.00942 Chinese Journal of Natural Medicines Diversity, bioactivities, and metabolic potentials of endophytic actinomycetes isolated from traditional medicinal plants in Sichuan, China QIU Peng 1, 2 , FENG Zhi-Xiang 1, 3∆ , TIAN Jie-Wei 1, 2 , LEI Zu-Chao 1, 2 , WANG Lei 1, 2 , ZENG Zhi-Gang 3 , CHU Yi-Wen 3 , TIAN Yong-Qiang 1, 2* 1 Key laboratory of Leather Chemistry and Engineering, Ministry of Education and College of Light Industry, Textile & Food Engineering, Sichuan University, Chengdu, 610065, China; 2 Department of Pharmaceutical and Biological Engineering, School of Chemical Engineering, Sichuan University, Chengdu 610065, China; 3 Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu 610052, China Available online 20 Dec., 2015 [ABSTRACT] The present study was designed to determine the taxonomic diversity and metabolic activity of the actinomycetes community, including 13 traditional medicinal plants collected in Sichuan province, China, using multiple approaches such as morphological and molecular identification methods, bioactivity assays, and PCR screening for genes involved in antibiotics biosynthesis. 119 endophytic actinomycetes were recovered; 80 representative strains were chosen for 16S rRNA gene partial sequence analyses, with 66 of them being affiliated to genus Streptomyces and the remaining 14 strains being rare actinomycetes. Antimicrobial tests showed that 12 (15%) of the 80 endophytic actinomycetes displayed inhibitory effects against at least one indicator pathogens, which were all assigned to the genus Streptomyces. In addition, 87.5% and 58.8% of the isolates showed anticancer and anti-diabetic activities, respectively. Meanwhile, the anticancer activities of the isolates negatively correlated with their anti-diabetic activities. Based on the results of PCR screening, five genes, PKS-I, PKS-II, NRPS, ANSA, and oxyB, were detected in 55.0%, 58.8%, 90.0%, 18.8% and 8.8% of the 80 actinomycetes, respectively. In conclusion, the PCR screening method employed in the present study was conducive for screening and selection of potential actinomycetes and predicting potential secondary metabolites, which could overcome the limitations of traditional activity screening models. [KEY WORDS] Endophytic actinomycetes; Medicinal plants; Diversity; Bioactivity; PCR screening [CLC Number] R931.2 [Document code] A [Article ID] 2095-6975(2015)12-0942-12 Introduction Actinomycetes are known as the world’s greatest reservoir of natural antibiotics [1] , but the frequency of discovering structurally new bioactive compounds is [Received on] 13-Jan.-2015 [Research funding] This work was supported by Sichuan Science and Technology Project (No. 2014JY0199) and the Fundamental Research Funds for Central University (SCU2005D008). [ * Corresponding author] Tel/Fax: 86-28-85405237, E-mail: yqtian@scu.edu.cn. ∆ These authors contributed equally to this work. These authors have no conflict of interest to declare. apparently decreasing in recent years [2-3] . Endophytic actinomycetes have been proven to be a new untapped source of novel actinomycetes [4] . Endophytes have been confirmed to have diverse intimate associations with hosts, such as nitrogen fixation, biosynthetic gene exchange, and production of phytohormones [5-8] . Several new strategies have been successfully applied to find new species or novel chemical candidates with potential bioactivities, including the utilization of eDNA [9] and combinational biosynthesis [10] . It is also meaningful to search and exploit endophytic microorganisms. The unique interior niches of endophytic actinomycetes have attracted extensive attention in developing novel natural bioactive compounds or unusual biochemical mechanism to relieve problems in rare-resource substitution and cope with drug-resistance situations [11-12] .