[Role of Luxs gene on regulation of virulence factors in Salmonella typhimurium].
OBJECTIVE
To investigate the role of Luxs gene on the regulation of virulence factors in Salmonella typhimurium.


METHODS
Luxs gene knock-out strain of Salmonella typhimurium of the line 14028S was constructed. Media with Luxs gene knock-out 14028S or wild type 14028S bacteria were added into the media of cultured human intestinal epithelial cells of the line Caco. The numbers of colony formation unit (cfu) were calculated so as to compare the invasion ability. Northern blotting was performed to examine the Luxs gene expression.


RESULTS
When the 14028S cells were in the early logarithmic phase the cfu number was 590, and in the middle and late logarithmic, and stationary phases, the cfu numbers were 246, 57, and 13 respectively. The Luxs gene expression levels increased gradually along with the bacterial growth into different phases. The cfu number A600 nm = 0.25 of the Luxs gene knock-out strain was 597, significantly higher than that of the wild type (315, P < 0.05).


CONCLUSIONS
Luxs gene may be a negative regulator on the invasion ability of Salmonella typhimurium.
Chen
Ming-hong
MH
Institute of Gastroenterology, Fujian Provincial Hospital, Fuzhou 350001, China. mhchen9035@yahoo.com.cn
Lin
Zhi-hui
ZH
Peng
Xiao-wei
XW
Pan
Xiu-zhen
XZ
D001426:Bacterial Proteins / Q000235:genetics*; D018938:Caco-2 Cells; D013437:Carbon-Sulfur Lyases / Q000235:genetics*; D017077:Culture Media, Conditioned; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D012486:Salmonella typhimurium / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity*; D014774:Virulence / Q000235:genetics
D001426:Bacterial Proteins; D017077:Culture Media, Conditioned; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria