大肠杆菌F18菌毛A亚单位基因的多样性分析

根据已经发表的大肠杆菌F18ab菌毛A亚单位(FedA／ab)的基因序列(fedA／ab)设计1对引物，利用PCR技术从本实验室保存的10株大肠杆菌(F107／86、YCED1、YCED2、C、D、E、12F、2134P、8199、8813)中分别扩增到一段序列．并克隆至pGEM-T载体，获得重组质粒TF107A、TYCED1A、TYCED2A、TCA、TDA、TEA、T12FA、T8813A、T8199A、T2134PA。通过序列测定，并与已发表的fedA／ab进行比较、基因树分析，可将这10个菌株分为2个基因群，其中F107／86、YCED1、YCED2、C、D、12F与fedA／ab具有高度同源性，属于fedA／ab．大小为513bp；E、8813、8199、2134P构成另一单独的分支，属于fedA／ac．大小为516bp。

The Genic Diversity of the Major Subunit fedA Gene of the Fimbriae F18 of E. Coli

A pair of primers were designed and synthesized according to fedA of fimbriae F18ab (fedA/ab),and the coordinate subunit genes were amplificated from ten different Escherichia coli strains,F107/86,YCED1,YCED2,C,D,E,12F,2134P,8199 and 8813.Thereinto,F107/86 is display fimbriae F18ab,whereas 2134P,8199 and 8813 are all display fimbriae F18ac.All the PCR products were cloned into pGEM-T vector respectively.Color screening,PCR and restriction endonucleases analysis were used to identify the recombinant plasmids,and ten recombinant plasmids,TF107A,TYCED1A,TYCED2A,TCA,TDA,TEA T12FA,T8813A,T8199A and T2134PA were obtained.The ten recombinant plasmids sequences were analyzed,and compared with the published sequences of fedA/ab.The data of the sequences of the ten genes were showed that they belong to two different genic group,fedA/ab (513 bp) and fedA/ac (516 bp).F107/86,YCED1,YCED2,C,D,12F are fall into fedA/ab group,whereas E,8813,8199 and 2134P are fall into fedA/ac group,although they are possessed of high identity at nucleoide and amio acid level with fedA/ab group respectively.