BldM对密旋链霉菌Act12形态发育及抗生素合成的调控

BldM regulates morphological development and antibiotic synthesis in Streptomyces pactum Act12

摘要:

【目的】以多效生防菌株——密旋链霉菌(Streptomyces pactum) Act12为研究材料，探究转录因子BldM对生防链霉菌Act12形态发育及抗生素合成的调控作用。【方法】通过基因工程手段构建bldM基因缺失突变株∆bldM及过表达突变株OE-bldM，利用扫描电镜观察、抑菌实验、高效液相色谱检测和实时荧光定量PCR探究缺失突变株∆bldM及过表达突变株OE-bldM与野生型(wild) Act12在形态发育、生长速率、寡霉素产量及抗病原菌能力等方面的差异。【结果】经测序验证bldM基因缺失突变体∆bldM及过表达突变体OE-bldM均构建成功，其中∆bldM寡霉素D产量明显降低且无法形成气生菌丝，而过表达突变株OE-bldM的气生菌丝更加密集，产孢更为丰富。与野生型菌株相比，OE-bldM的寡霉素D产量增加了23%，编码寡霉素核心合成酶基因的转录水平上调了2-3倍，抑菌活性显著增强。【结论】全局性转录调控因子BldM不但能影响Act12气生菌丝及孢子形成，并且参与正调控Act12寡霉素的合成，本研究结果为转录因子BldM的调控功能进行了新的挖掘和补充，并为后续深入研究密旋链霉菌Act12的生长代谢途径和调控机制提供了参考。

Abstract:

[Objective] To investigate the regulatory role of the transcription factor BldM in the morphological development and antibiotic synthesis of Streptomyces pactum Act12, a biocontrol strain with multiple effects. [Methods] The bldM-deleted mutant strain ∆bldM and the bldM-overexpressing mutant strain OE-bldM were constructed by genetic engineering. The scanning electron microscopy, antibacterial experiment, high performance liquid chromatography, and real-time quantitative PCR were employed to compare the morphological development, growth rate, oligomycin yield, and resistance to pathogens, respectively, between ∆bldM, OE-bldM, and the wild-type strain Act12. [Results] The sequencing results proved that ∆bldM and OE-bldM were successfully constructed. ∆bldM showed significantly reduced production of oligomycin D and was incapable of forming aerial hyphae. OE-bldM presented dense aerial hyphae and active sporulation. Compared with the wild type, OE-bldM showed an increase of 23% in the yield of oligomycin D and the up-regulation of 2–3 times in the transcriptional levels of the genes encoding oligomycin core synthetase. Moreover, the antimicrobial activity of OE-bldM remarkably enhanced. [Conclusion] The global transcriptional regulator BldM can not only affect the formation of aerial hyphae and sporulation but also participate in the positive regulation of oligomycin synthesis in Act12. The results of this study supplement the knowledge about the regulatory function of BldM and provide a reference for further research on the growth, metabolism, and regulation mechanism of S. pactum Act12.