伤寒杆菌Luxs基因在细菌毒力调节中的作用

Role of Luxs gene on regulation of virulence factors in Salmonella typhimurium

目的探讨伤寒杆菌Luxs基因在细菌毒力调节中的作用。方法构建伤寒杆菌Luxs基因敲除菌株，比较野生型伤寒杆菌菌株与Luxs基因敲除菌株的侵袭细胞能力。利用Northem杂交技术检测不同生长时期伤寒杆菌Luxs基因转录水平。结果伤寒杆菌的侵袭能力与细菌生长时期有关，早对数生长期伤寒杆菌的侵袭能力最强，其侵袭细胞的菌落数为590菌落形成单位（cfu）。在中对数生长期、晚对数生长期及平台期，其侵袭细胞的菌落数分别为246、57和13cfu。随着细菌生长至中、晚对数生长期及平台期，Luxs基因的转录信号逐渐增强。野生型伤寒杆菌菌株侵袭细胞的菌落数为315cfu，Luxs基因敲除菌株侵袭细胞的菌落数为597cfu。结论伤寒杆菌Luxs基因对伤寒杆菌侵袭能力起着负调节作用。

Objective To investigate the role of Luxs gene on the regulation of virulence factors in Salmonella typhimuriumn. 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 ）. Conclusion Luxs gene may be a negative regulator on the invasion ability of Salmonella typhimurium.