BldM regulates morphological development and antibiotic synthesis in Streptomyces pactum Act12

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.

Key words:Streptomyces pactum Act12;oligomycin;bldM;morphological development