论文部分内容阅读
假单胞菌菌株G5是分离自香菜(Coriandrum sativumL.)茎内的一株内生菌,经BIOLOG系统分析其底物利用图谱,初步鉴定为桔黄假单胞菌Pseudomonas aurantiaca。大量研究已表明许多革兰氏阴性细菌应用群体感应系统,通过感应扩散性小信号分子―乙酰基高丝氨酸内酯(N-acyl homoserine lactones,AHLs),以种群密度依赖的方式调控基因表达,控制植物相关细菌的多种表型。本研究组合应用AHLs检测菌株Chromobacterium violaceum CV026和薄层层析分析,初步检测出菌株G5可产生几种可检测水平的AHLs信号分子,其中以N-hexanoyl-homoserine lactone(C6-HSL,HHL)为主,迁移率Rf值为0.4。进一步克隆和测序了该菌株中由PhzI和PhzR组成的群体感应quorumsensing系统的编码基因phzIR,并在大肠杆菌中异源表达了AHLs信号分子合成酶基因phzI。序列和系统进化分析表明它们与假单胞菌属其他的phzIR基因有高度同源性和进化上的保守性。
Pseudomonas strain G5 is an endophyte isolated from the stem of Coriandrum sativum L. Its substrate utilization profile was analyzed by BIOLOG system and initially identified as Pseudomonas aurantiaca. Numerous studies have shown that many Gram-negative bacteria use a population sensing system that regulates gene expression in a population density-dependent manner by sensing the diffusible small signal molecules, such as N-acyl homoserine lactones (AHLs) Multiple phenotypes of plant-associated bacteria. In this study, AHLs were used to detect several AHLs signaling molecules that produced detectable levels by using the AHLs detection strain Chromobacterium violaceum CV026 and thin-layer chromatography. Among them, N-hexanoyl-homoserine lactone (C6-HSL, HHL) The main, the mobility Rf value of 0.4. The gene phzIR encoding the quorum sensing system of the quorum sensing system consisting of PhzI and PhzR was further cloned and sequenced. The phzI gene of AHLs was expressed heterologously in Escherichia coli. Sequence and phylogenetic analysis indicated that they were highly homologous and evolutionarily conserved among other phzIR genes of Pseudomonas.