绿针假单胞菌HT66中ompR基因的功能

Function of ompR gene in Pseudomonas chlororaphis HT66

摘要:

【背景】植物根部存在大量对植物生长有促进或对病原菌有拮抗作用的有益细菌，是当前农业微生物研究的热点之一。其中，绿针假单胞菌HT66是一株可高效合成吩嗪-1-甲酰胺(PCN)的环境友好型生防菌株。【目的】探究在绿针假单胞菌HT66中ompR基因的生理功能，以及其对菌株生防作用的影响。【方法】通过基因无痕敲除的方法构建HT66菌株的ompR基因缺失突变株，对比研究突变株与野生株在生长速率、渗透压感应、生物膜的合成、pH耐受性、群集运动和PCN产量的变化。【结果】与野生株相比，ompR基因缺失突变株的细胞生物量微量减少，生物膜的合成减少31.5%，群集运动以及对渗透压和pH的耐受性明显下降，但是其PCN产量较野生株提高了57.8%。【结论】在HT66菌株中，ompR基因对其运动性、环境耐受性和生理生防功能均有一定程度的调控作用。本研究丰富了绿针假单胞菌的代谢通路，此报道将对后续PCN合成机制的研究和应用提供一定的理论依据。

Abstract:

[Background] Plant rhizosphere growth-promoting bacteria are one of the hotspots in the current research of agricultural microorganisms because they promote plant growth or have antagonistic effects on pathogenic bacteria. Among them, Pseudomonas chlororaphis HT66 is a non-pathogenic biocontrol strain that can efficiently synthesize phenazine-1-carboxamide (PCN) — a promising and environmental friendly agricultural antibiotic. [Objective] To study the physiological function of ompR gene in P. chlororaphis HT66 and its biocontrol efficiency. [Methods] The ompR gene deletion mutant of HT66 strain was constructed by scar-less gene knockout method. We studied the effects of the mutation on the growth rate, biofilm synthesis, tolerance to pH and osmotic pressure, swarming mobility and PCN production. [Results] Compared with the wild-type strain, the ompR gene deletion inactivated mutant showed a slight reduction in cell biomass. The biofilm decreased by 31.5%, whereas the swarming mobility of the strain and the tolerance to osmotic pressure and pH decreased. However, the yield of PCN increased by 57.8% in the mutant strain. In HT66 strain, the ompR gene has a certain degree of regulation of its motility, environmental tolerance and physiological and biological functions. [Conclusion] Our findings enriched the metabolic pathway of P. chlororaphis, and will provide a basis for the research and application of the subsequent PCN synthesis mechanism.