豬霍亂沙門氏桿菌flgM與flgN基因的選殖及其功能的探討

Abstract

豬霍亂沙門氏桿菌（Salmonella choleraesuis）屬於腸內科細菌，為一種兼氣細菌，會攻擊寄主的腸道上皮組織，是一種人畜共通傳染的病原菌，感染豬隻嚴重時會引起全身性的敗血症及腦炎，造成養豬戶及農業上的重大損失。 本論文在研究flgM與flgN在鞭毛形成過程的功能，在前人的研究中，發現在腸內細菌科中flgM及flgN與調控鞭毛其中一個構造-filament的形成有關。 本研究首先分別選殖出豬霍亂沙門氏桿菌中flgM與flgN基因，並進行比對，發現這兩種基因在腸內科細菌中的序列幾乎是相同的，表示這兩個基因是很保守的基因。另一方面建構這兩個基因flgM和flgN基因同時失去功能的突變株，發現此突變株鞭毛有明顯減少的現象，且細菌的移動力也比正常細菌減少許多；再將正常的flgM、flgN或flgM及flgN基因分別送入突變株中，結果發現當flgM及flgN基因一起送入突變株中時，細菌鞭毛數和移動力的確有恢復，不過並沒有完全恢復，而將flgM單獨送入時細菌鞭毛數和移動力也有恢復，最後將flgN送入突變株中,發現鞭毛很少，移動力也幾乎等於零，而上述這些結果推測是因為在flgM和flgN之間某些未知的交互作用模式存在所造成的。

Salmonella choleraesuis is a host adapted, facultative intracellular pathogen and belongs to the family Enterobacteriaceae. It is a pathogen of human and pigs, more serious in pigs. It causes swine septicemia, enterocolitis or bacteremic localization as pneumonia, or occasionally as meningitis or encephalitis. This study is focused on flgM and flgN of Salmonella choleraesuis. These two genes is responsible for filament formation. Filament is one part of flagellum. For investigating the function of flgM and flgN, the genes were cloned from Salmonella choleraesuis. A knockout strain that flgM and flgN was inactivated by inserting an Ω fragment into the genes. Then vector containing normal flgM, flgN or flgM and flgN was introduced into the knockout strain respectively. The data showed that when flgM and flgN was inactivated, the number of flagella were fewer and motility were lawer than normal bacteria. When normal flgM and flgN was re-introduced into knockout strain, the number of flagella and motility were recovered, but not the same as normal bacteria. The results were the same when normal flgM was re-introduced into knockout strain. However, the normal flgN could not restore the number of flagella and the motility of knockout strain. The results suggested that flgM and flgN could interact in some way to affect the formation of flagella, not by single function of flgM or flgN.