内生拮抗放线菌FRo2的鉴定及抑菌活性物质的分离

Identification of antagonistic endophytic actinomycete FRo2 and isolation of its antimicrobial composition

摘要:

【目的】鉴定从东乡野生稻根部分离得到的对多种农作物病原真菌具有拮抗活性的内生放线菌株FRo2，并对其抑菌活性物质进行分离。【方法】根据FRo2形态特征观察、生理生化特性、细胞壁组分和16S rRNA基因序列对其进行鉴定。采用管碟法和菌丝生长速率法测定了该菌株的抗菌活性，活性追踪法结合正相硅胶柱层析及凝胶(Sephadex LH-20)柱层析等技术对抑菌组分进行分离，并通过NMR对抑菌活性物质进行解析。【结果】菌株FRo2属于链霉菌属，与娄彻氏链霉菌(Streptomyces rochei)极为相似。该菌株发酵液对小麦赤霉菌、立枯丝核菌等7种主要农作物致病菌具有较好的抑制活性；从菌株FRo2发酵液中分离得到抑菌活性化合物AW2，结构鉴定为邻苯二甲酸二丁酯。【结论】研究阐明了内生放线菌FRo2抑菌活性物质，也为该菌今后的农业生防应用提供物质基础。

关键词:内生放线菌，菌株鉴定，抗菌活性，邻苯二甲酸二丁酯

Abstract:

[Objective] Endophytic actinomycete FRo2 with activity against agricultural pathogenic fungi was isolated from the roots of Dongxiang wild rice (Oryza rufipogon). We identified FRo2 and separated its antimicrobial substances. [Methods] Morphological, physiology and biochemistry characteristics, chemotaxonomy analysis and 16S rRNA gene sequences were used to identify FRo2. The bioactivities were determined by tube plate method and mycelium growth inhibition method. According to nuclear magnetic resonance spectroscopy (NMR) extrapolation result, one antimicro-bial substances in the metabolites of FRo2 through normal-phase silica gel column chromatography and gel (Sephadex LH-20) column chromatography with bioassay-guided fractionation was isolated. [Results] FRo2 belonged to Streptomyces sp. and was similar to Streptomyces rochei. The metabo-lites had high inhibitory activities against Fusarium graminearumt, Rhizoctonia solani and other five agricultural pathogenic fungi, and the antimicrobial substances AW2 was elucidated as Dibutyl phthalate. [Conclusion] The material basis of the antibacterial constituents in antagonistic actinomy-cetes strain FRo2 was further clarified, and strain FRo2 is deserved to develop an biocontrol.

Key words:endophtic actinomycetes, strain identification, antimicrobial activity, Dibutyl phthalate