Abstract: In order to understand the biosynthetic potential of medicinal endophytic actinomycetes,39 strains isolated from roots of 5 species of medicinal plants were fermented in two different media.Then methanol was used to extract the fermentations.After getting the crude extracts,the bioactivity test of crude extracts were performed on 13 strains of indicator bacteria and fungi.About 32(82%)of the crude extracts exhibited bioactivity to one of the 13 indicator bacteria and fungi at least.To further verify the biosynthetic potential of the 39 strains,the polyketide synthases(PKS)and nonribosomal peptide synthetases(NRPS)genes were amplified.One of the several genes at least could be amplified from genomic DNAs of all of the strains,and the proportions for the type I PKS(1),type I PKS(2),type II PKS,NRPS(1) and NRPS(2) are 59%,62%,82%,100% and 100%,respectively.These results above suggested- that the endophytic actinomycetes from medical plants possessed significant biosynthetic potential,and they could produce active compounds under certain conditions.

Key words: endophytic actinomycetes, antimicrobial activity, polyketide synthase genes, non ribosomal peptide synthetase gene