欧洲疮痂链霉菌F5的鉴定及其抗菌活性

Characterization and antipathogenic activity of Streptomyces europaeiscabiei F5 from the rhizosphere of pigeon pea

摘要:

【背景】木豆(Cajanus cajan)是一种具有多种药理活性的药用植物，目前对其根际功能放线菌的认识和研究有限，有必要对其应用开发潜力进行研究。【目的】从木豆根际土中筛选一株对植物病原菌和常见病原菌具有广谱拮抗活性的放线菌菌株，鉴定菌株的分类地位、相关代谢产物及可能的生物合成途径，为该菌株的开发应用提供数据支撑。【方法】以7种常见植物病原真菌及8种常见病原菌为指示菌，采用平板对峙法和滤纸片扩散法筛选具有广谱抗菌活性的放线菌菌株，基于形态观察与系统发育分析对该菌株进行分类鉴定，并通过高分辨质谱和超高效液相色谱-串联质谱(UPLC-MS/MS)对活性菌株的次生代谢产物进行鉴定与验证。采用PCR扩增菌株聚酮合成酶Ⅰ (polyketide synthase，PKS-Ⅰ)和非核糖体多肽合成酶(non-ribosomal peptide synthetase，NRPS)基因，明确其活性代谢产物可能的生物合成途径。【结果】通过抑菌试验筛选得到拮抗放线菌F5，确定其为欧洲疮痂链霉菌(Streptomyces europaeiscabiei)，F5菌株基因组中含有编码PKS-Ⅰ和NRPS合成的相关基因，采用高分辨质谱和UPLC-MS/MS从其发酵液中鉴定并确证了格尔德霉素与大黄素两种具有抗菌活性的次生代谢产物。【结论】首次筛选鉴定了一株木豆根际放线菌Streptomyces europaeiscabiei F5，该菌株具有广谱抑菌活性，可代谢产生格尔德霉素和大黄素等活性物质，具有在农业和医药领域的应用潜力，值得进一步研究。

Abstract:

[Background] Pigeon pea (Cajanuscajan) is a medicinal plant with a variety of pharmacological activities. Considering the limited understanding and research on actinomycetes in the rhizosphere of pigeon pea, it is necessary to study their application and development potential. [Objective] An actinomycete strain with broad-spectrum antagonistic activity against plant pathogens and common pathogens was screened out from the rhizosphere soil of pigeon pea. The taxonomic status, metabolites and possible biosynthetic pathways were identified to provide data support for the development and application of the strain. [Methods] With 7 plant pathogenic fungi and 8 common pathogens as the indicators, plate confrontation method and filter paper diffusion method were used to screen out the actinomycete strain with broad-spectrum antagonistic activity. The selected strain was identified based on morphological characteristics and phylogenetic tree, and the secondary metabolites of the strain were detected by UPLC-Q-Exactive high-resolution mass spectrometry and UPLC-MS/MS. The polyketide synthaseⅠ(PKS-Ⅰ) and non-ribosonmal peptide synthetase (NRPS) genes of the strain were amplified by PCR to clarify the biosynthetic pathways of the antimicrobial substances. [Results]The actinomycete F5 with broad-spectrum antagonistic activity was screened out and identified as Streptomyces europaeiscabiei. The strain was able to produce active metabolites like geldanamycin and emodin. The genes encoding PKS-Ⅰand NRPS were presented in strain F5. [Conclusion] Streptomyces europaeiscabiei F5 from the rhizosphere of pigeon pea is isolated and identified for the first time. It has broad-spectrum antagonistic activity and can produce antimicrobial substances like geldanamycin and emodin, thus demonstrating great application potential in agriculture and medicine and worth of further research.