地黄内生放线菌的分离及地黄轮纹病拮抗菌Streptomyces folium leaf-16的新种鉴定

药用植物内生放线菌具有合成天然活性化合物的潜力，放线菌新种是寻找新型抗生素先导化合物的一个重要来源。【目的】挖掘药用植物地黄内生放线菌资源，并对地黄轮纹病拮抗菌株leaf-16进行新种鉴定。【方法】本研究采用五步消毒法分离河南道地药材地黄的内生放线菌，以地黄轮纹病原真菌草茎点霉(Phoma herbarum)为指示菌，采用平板对峙法筛选对该病菌有抑制作用的菌株，16S rRNA基因测序发现一株抗地黄轮纹病的放线菌新种leaf-16。通过形态、生理生化、细胞壁化学组分和分子生物学等特征对菌株leaf-16进行多相分类学鉴定。【结果】经平板对峙实验得到8株抗地黄轮纹病的放线菌，其中菌株leaf-16经16S rRNA基因测序、形态比较、生理生化、化学组分和分子生物学以及DNA-DNA杂交分析，确定菌株leaf-16为1株链霉菌新种，并命名为Streptomyces folium。【结论】菌株leaf-16为1株链霉菌新种，具有抑制地黄轮纹病原真菌的活性，为进一步分离新型抗地黄轮纹病的生物制剂奠定物质基础。

Isolation of endophytic actinomycetes from Rehmannia glutinosa and identification of a new species Streptomyces folium leaf-16 resistant to Phoma herbarum

Endophytic actinomycetes of medicinal plants have the potential to synthesize natural active compounds, and new species of actinomycetes are an important source for discovering new compounds. Objective] To explore the resources of endophytic actinomycetes of the medicinal plant Rehmannia glutinosa, and identify a new strain leaf-16 with the activity against the pathogenic fungus causing the ring rot of R. glutinosa. Methods] In this study, we used five-step sterilization method to isolate the endophytic actinomycetes of R. glutinosa in Henan Province. Phoma herbarum, the pathogenic fungus causing the ring rot of R. glutinosa, was used as the indicator fungus to screen the antagonistic strains via the plate confrontation assay. For the antagonistic strains, 16S rRNA gene sequencing revealed a new actinomycete strain leaf-16, which was then identified based on the morphological, physiological, biochemical, and molecular characteristics, as well as cell wall components and DNA-DNA hybridization. Results] We obtained eight actinomycete strains resistant to P. herbarum by plate confrontation assay. Among them, strain leaf-16 was identified as a new species of Streptomyces and named Streptomyces folium. Conclusion] Strain leaf-16 is a new species of Streptomyces and has the activity of inhibiting the pathogenic fungus caused ring rot disease of R. glutinosa. This new species lays a material foundation for further isolation of new bioactive substances against the ring rot of R. glutinosa.