University of Copenhagen, Faculty of Life Sciences, Department of Food Science, Food Microbiology, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark.
Int J Food Microbiol. 2011 Oct 3;149(3):269-73. doi: 10.1016/j.ijfoodmicro.2011.06.011. Epub 2011 Jun 25.
The luxS gene involved in quorum sensing has been shown to control different behaviour of probiotic lactobacilli. In this study we investigated if luxS in Lactobacillus acidophilus NCFM was up-regulated in response to Listeria monocytogenes EGD-e. The two bacterial strains were grown in mono- and co-culture and the growth of both bacteria and the transcriptional level of luxS in L. acidophilus cells were monitored. Contrary to L. acidophilus, the growth of L. monocytogenes was significantly affected by co-cultivation. Transcriptional analysis showed that the expression of luxS increased during exponential growth in L. acidophilus cells with the highest level in the late-exponential growth phase, decreasing in the stationary phase. Following co-cultivation with L. monocytogenes, the transcriptional level of luxS increased significantly in mid-exponential growing cells of L. acidophilus after incubation with viable L. monocytogenes cells and by addition of cell-free culture supernatant of L. monocytogenes, whereas incubation with heat killed cells of L. monocytogenes had no effect on the transcriptional level. This could indicate that the up-regulation of luxS is due to a response to a secreted compound produced by L. monocytogenes cells.
参与群体感应的 luxS 基因已被证明可以控制益生菌乳杆菌的不同行为。在这项研究中，我们研究了嗜酸乳杆菌 NCFM 中的 luxS 是否会对单核细胞增生李斯特菌 EGD-e 作出响应而上调。将两种细菌在单独和共培养中生长，并监测两种细菌的生长和嗜酸乳杆菌细胞中 luxS 的转录水平。与嗜酸乳杆菌相反，单核细胞增生李斯特菌的生长受到共培养的显著影响。转录分析表明，luxS 的表达在嗜酸乳杆菌细胞的指数生长期增加，在晚指数生长期达到最高水平，在静止期下降。与单核细胞增生李斯特菌共培养后，用活单核细胞增生李斯特菌细胞孵育并添加单核细胞增生李斯特菌无细胞培养上清液后，嗜酸乳杆菌中 luxS 的转录水平在指数生长期中期细胞中显著增加，而用热杀死的单核细胞增生李斯特菌细胞孵育则对转录水平没有影响。这可能表明 luxS 的上调是由于对单核细胞增生李斯特菌细胞分泌的化合物的反应。
