Department of Microbiology, University College Cork, Cork, Ireland.
PLoS One. 2012;7(7):e40592. doi: 10.1371/journal.pone.0040592. Epub 2012 Jul 10.
Lactobacillus ruminis is one of at least twelve motile but poorly characterized species found in the genus Lactobacillus. Of these, only L. ruminis has been isolated from mammals, and this species may be considered as an autochthonous member of the gastrointestinal microbiota of humans, pigs and cows. Nine L. ruminis strains were investigated here to elucidate the biochemistry and genetics of Lactobacillus motility. Six strains isolated from humans were non-motile while three bovine isolates were motile. A complete set of flagellum biogenesis genes was annotated in the sequenced genomes of two strains, ATCC25644 (human isolate) and ATCC27782 (bovine isolate), but only the latter strain produced flagella. Comparison of the L. ruminis and L. mali DSM20444(T) motility loci showed that their genetic content and gene-order were broadly similar, although the L. mali motility locus was interrupted by an 11.8 Kb region encoding rhamnose utilization genes that is absent from the L. ruminis motility locus. Phylogenetic analysis of 39 motile bacteria indicated that Lactobacillus motility genes were most closely related to those of motile carnobacteria and enterococci. Transcriptome analysis revealed that motility genes were transcribed at a significantly higher level in motile L. ruminis ATCC27782 than in non-motile ATCC25644. Flagellin proteins were isolated from L. ruminis ATCC27782 and from three other Lactobacillus species, while recombinant flagellin of aflagellate L. ruminis ATCC25644 was expressed and purified from E. coli. These native and recombinant Lactobacillus flagellins, and also flagellate L. ruminis cells, triggered interleukin-8 production in cultured human intestinal epithelial cells in a manner suppressed by short interfering RNA directed against Toll-Like Receptor 5. This study provides genetic, transcriptomic, phylogenetic and immunological insights into the trait of flagellum-mediated motility in the lactobacilli.
鼠李糖乳杆菌是至少 12 种运动但特征描述较差的乳杆菌属种之一。在这些种中，只有鼠李糖乳杆菌从哺乳动物中分离出来，并且该种可被认为是人类、猪和牛胃肠道微生物群的原籍成员。在这里，研究了 9 株鼠李糖乳杆菌菌株以阐明乳杆菌运动的生物化学和遗传学。从人类中分离的 6 株菌株是非运动的，而 3 株牛分离株是运动的。在 2 株测序的鼠李糖乳杆菌（ATCC25644[人分离株]和 ATCC27782[牛分离株]）基因组中注释了完整的一套鞭毛生物发生基因，但只有后者菌株产生了鞭毛。比较鼠李糖乳杆菌和 L. mali DSM20444(T)运动基因座表明，它们的遗传内容和基因顺序大致相似，尽管 L. mali 运动基因座被编码鼠李糖利用基因的 11.8 Kb 区域中断，而该区域不存在于鼠李糖乳杆菌运动基因座中。39 种运动细菌的系统发育分析表明，乳杆菌运动基因与运动的 carnobacteria 和肠球菌的基因最密切相关。转录组分析表明，在运动的鼠李糖乳杆菌 ATCC27782 中，运动基因的转录水平显著高于非运动的鼠李糖乳杆菌 ATCC25644。从鼠李糖乳杆菌 ATCC27782 和其他 3 种乳杆菌属种中分离到了鞭毛蛋白，而从无鞭毛的鼠李糖乳杆菌 ATCC25644 中表达和纯化了重组 flagellin。这些天然和重组的乳杆菌鞭毛蛋白，以及鞭毛的鼠李糖乳杆菌细胞，以 Toll-Like Receptor 5 短发夹 RNA 抑制的方式触发培养的人肠上皮细胞中白细胞介素-8 的产生。这项研究提供了遗传、转录组、系统发育和免疫学方面的见解，阐明了乳杆菌属中鞭毛介导的运动特性。
