Diversity, activity and PCR screening of biosynthesis genes of endophytic actinomycetes isolated from Forsythia suspensa and Solanum torvum

Abstract:

14 strains of endophytic actinomycetes were isolated from the roots of ethnomedical plants, Forsythia suspensa and Forsythia suspensa, collected in Chengdu. The results of antimicrobial and anticancer activity assays of the fermentation crude extracts showed: 10 strains displayed inhibition to HepG2 cell line in varied degrees, accounting for 71% of total isolates; 3 strains exhibited antibacterial activity; and strain A263 showed acute cytotoxic activity and wide-spectrum of antibacterial activity. Based on similarity analysis of 16S rRNA gene partial sequences, strain A275 was indicated affiliate to genus Kribbella, and the remaining 13 strains were belong to genus Streptomyces. PCR screening of biosynthesis genes revealed 5 strains possess PKS-I, PKS-II, NRPS genes simultaneously, and strain A255, A263 possessed 3,5-AHBA synthetase gene additionally, while strain A275 was the only one found with oxyB gene. These results may deduce Streptomyces was the dominant actinomycetes in the roots of these ethnomedical plants. PCR screening of biosynthesis genes compensate the limitation of traditional screening model for bioactive substances tremendously. Endophytic actinomycetes were acknowledged with enormous potential of producing prolific bioactive compounds.