连翘和水茄内生放线菌的多样性、活性及生物合成基因的PCR筛查

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

摘要:

从采自成都地区的中药植物连翘Forsythia suspense和水茄Solanum torvum的根部分离到14株内生放线菌。活性筛选表明, 10株菌的发酵粗提物具有不同程度的抗肿瘤活性, 占全部菌株的71%; 3株菌具有抗细菌活性, 其中菌株A263具有较强的细胞毒活性和广谱抗细菌活性。基于16S rRNA基因部分序列的相似性分析表明, 菌株A275属于克里贝拉菌属Kribbella, 其余13株属于链霉菌属Streptomyces。多种生物合成基因的筛查实验表明, 5株菌同时具有PKS-I、PKS-II、NRPS型基因, 其中A255和A263还具有3,5-AHBA合酶基因, 但仅A275具有oxyB基因。结果可以推测, 链霉菌是这2种中药植物根部的优势内生放线菌, 生物合成基因的PCR筛查能极大地弥补传统活性筛选模型的不足, 内生放线菌具有产生丰富生物活性化合物的巨大潜力。

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.