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【目的】荧光假单胞菌(Pseudomonas fluorescens)2P24中PcoI/PcoR群体感应系统是调控生物膜形成与植物根部定殖能力的重要元件,同时该系统也受到多种上游因子的调控。利用遗传学方法研究P.fluorescens 2P24中gidA基因对群体感应系统的调控作用。【方法】将群体感应信号合成基因pcoI的转录报告质粒p970km-pcoIp转入菌株2P24和gidA基因突变体中以检测gidA对pcoI基因表达的影响,并利用报告菌Agrobacterium tumefaciens NTL4(pZLR4)测定菌株2P24及其衍生菌的信号N-乙酰高丝氨酸内酯(AHL)产量。【结果】gidA基因突变后pcoI基因的转录表达和AHL产量与野生型2P24相比显著降低。gidA基因突变体的游动能力没有受到明显的影响,但生物膜的形成显著低于野生型和互补菌株。小麦根部定殖实验表明,温室条件下gidA突变菌株在灭菌土和自然土中对小麦根尖和根围的定殖量较野生型和互补菌显著减少。此外,突变gidA基因并不影响菌株在LB培养基中的生长,但以葡萄糖、蔗糖、果糖、甘油、半乳糖、阿拉伯糖、甘露糖、木糖或山梨醇为唯一碳源时,gidA突变体的生长受到明显的抑制。【结论】GidA对假单胞菌2P24中的PcoI/PcoR群体感应系统、生物膜形成、定殖和碳源利用具有显著的正调控作用。
【Objective】 The PcoI / PcoR population-sensing system in Pseudomonas fluorescens 2P24 is an important component of regulating biofilm formation and plant root colonization, and the system is also regulated by a variety of upstream factors. Study on Regulation of gidA Gene in P. fluorescens 2P24 to Population Sensitive System by Genetic Method. 【Method】 The pcoI transcription reporter plasmid p970km-pcoIp was transformed into 2P24 and gidA mutant to detect the effect of gidA on pcoI gene expression. The strain 2P24 was detected by Agrobacterium tumefaciens NTL4 (pZLR4) And its derivatives of N-acetyl homoserine lactone (AHL). 【Result】 The results showed that the transcriptional expression of pcoI gene and the yield of AHL in gidA gene were significantly decreased compared with wild-type 2P24. The motility of gidA mutant was not significantly affected, but biofilm formation was significantly lower than that of wild-type and complementary strains. Root colonization experiments in wheat showed that colonization rate of gidA mutant in wheat germ and natural soil was significantly lower than that of wild-type and complementary bacteria. In addition, the mutant gidA gene did not affect the growth of the strain in LB medium. However, when glucose, sucrose, fructose, glycerol, galactose, arabinose, mannose, xylose or sorbitol were the sole carbon sources, the gidA mutant The growth was significantly inhibited. 【Conclusion】 GidA has a significant positive effect on PcoI / PcoR population Pseudomonas 2P24 induction system, biofilm formation, colonization and utilization of carbon sources.