中慢生型华癸根瘤菌Mesorhizobium huakuii AS9自体诱导物合成酶基因的筛选及其功能分析  

Screening for Autoinducer Synthase Gene in Mesorhizobium huakuii and the Analysis of Its Function

作　　者：袁全[1] 杨梦华[1] 郑会明[1] 钟增涛[1] 朱军[1] 

机构地区：[1]南京农业大学生命科学学院,南京210095

出　　处：《土壤》2009年第3期459-463,共5页Soils

基　　金：国家自然科学基金面上项目(30870065;30800013)资助

摘　　要：细菌在高细胞密度下通过产生一类化学信号分子(autoinducer,自体诱导物)感知细胞群体密度变化,从而对基因表达进行调控,这一现象被称为群体感应(quorum sensing)。以中慢生型华癸根瘤菌Mesorhizobium huakuii AS9为出发菌株,利用转座子随机突变的方法获得了自体诱导物缺失突变株YQ1,并克隆得到了其自体诱导物合成酶基因,命名为mrhI;构建PmrhI-lacZ转录融合表达质粒pYQ1,通过同源重组的方法得到在华癸根瘤菌中mrhI-lacZ融合表达而且mrhI基因突变菌株YQ3。突变株YQ3的培养液上清不含有自体诱导物分子,通过lacZ报告基因的表达发现mrhI的表达受自体诱导物的调控,说明mrhI基因是M.huakuii AS9的群体感应体系中的自体诱导物合成酶基因。Many bacteria regulate the expression of specialized gene sets in response to the population density at high density. This regulatory mechanism is called autoinduction or quorum-sensing. One autoindueer-deficient mutantYQ1 was obtained by screening Mesorhizobium huakuii mutated with mariner transposon. The autoinducer synthase gene was confirmed by sequencing and named mrhL The internal sequence was cloned into lacZ transcriptional fusion plasmid pVIK 112 to obtain the Pmrhl-lacZ fusion strainYQ3, from which we studied the expression and regulation of autoinducer synthase gene mrhl of M. huakuii. The result showed that the mrhl gene can be expressed only in the presence of added AHLs and was regulated in a cell density-dependent way. All of these results indicated that M.huakuii AS9 has the quorum sensing system, and in the same time, they also give some clues to the further study of the quorum sensing system of rhizobia species.

关 键 词：中慢生华癸根瘤菌 群体感应 自体诱导物合成酶基因 

分 类 号：Q933[生物学—微生物学]