假单胞菌H78中PhoR/B系统对磷元素吸收及其藤黄绿菌素合成的调控

Regulation of PhoR/B system on utilization of phosphorus and Plt biosynthesis in Pseudomonas sp. H78

摘要:

【目的】研究根际荧光假单胞菌(Pseudomonas protegens) H78中双组分系统PhoR/B对Pst磷转运系统以及Plt生物合成的调控作用。【方法】通过同源重组的方法敲除phoR和phoB基因；使用lacZ报告基因融合质粒研究PhoR/B系统对Pst磷转运系统表达的调控；在不同磷浓度下测定H78野生型及H78phoBR突变株的生长，并在KMB培养基中测定其Plt产量。【结果】H78野生型中pstS′-′lacZ融合质粒表达的LacZ酶活是H78phoBR突变株的15倍；在磷饥饿条件下H78的生长是H78phoBR菌株的3倍；在KMB培养基中，H78的Plt产量为H78phoBR菌株的2倍。【结论】PhoR/B系统正调控Pst转运系统的表达；在磷饥饿条件下，PhoR/B促进磷元素的吸收和利用；PhoR/B同时对Plt生物合成存在一定程度的正调控作用。

Abstract:

[Objective] Pseudomonas protegens H78 can secrete three antibiotics including pyoluteorin (Plt), pyrrolnitrin and 2,4-diacetylphloroglucinol. This study focused on regulation of the two component system PhoR/B on phosphorus absorption and utilization and Plt biosynthesis. [Methods] phoR and phoB genes were deleted using non-scar homologous recombination method. The lacZ reporter gene was used to assess the regulation of PhoR/B system on Pst phosphorus transport system. The cell growth of wild-type and mutant was determined, cultured in minimal medium containing different concentrations of phosphate. The production of Plt was determined in KB medium. [Results] The β-galactosidase activity of pstS′-′lacZ fusion in H78 was 15 times that in mutant. The growth of H78 was three times that in mutant when phosphate starvation. The production of Plt in H78 was two times that in mutant in KMB medium. [Conclusion] PhoR/B system positively regulates the expression of the Pst phosphorus transport system. PhoR/B facilitates phosphorus absorption and utilization during phosphate starvation and positively regulates the Plt biosynthesis as well.