Denou Emmanuel, Berger Bernard, Barretto Caroline, Panoff Jean-Michel, Arigoni Fabrizio, Brüssow Harald
Nestlé Research Centre, Nestec Ltd., P.O. Box 44, CH-1000 Lausanne 26, Switzerland.
J Bacteriol. 2007 Nov;189(22):8109-19. doi: 10.1128/JB.00991-07. Epub 2007 Sep 7.
Work with pathogens like Vibrio cholerae has shown major differences between genes expressed in bacteria grown in vitro and in vivo. To explore this subject for commensals, we investigated the transcription of the Lactobacillus johnsonii NCC533 genome during in vitro and in vivo growth using the microarray technology. During broth growth, 537, 626, and 277 of the 1,756 tested genes were expressed during exponential phase, "adaptation" (early stationary phase), and stationary phase, respectively. One hundred one, 150, and 33 genes, respectively, were specifically transcribed in these three phases. To explore the in vivo transcription program, we fed L. johnsonii containing a resistance plasmid to antibiotic-treated mice. After a 2-day washout phase, we determined the viable-cell counts of lactobacilli that were in the lumina and associated with the mucosae of different gut segments. While the cell counts showed a rather uniform distribution along the gut, we observed marked differences with respect to the expression of the Lactobacillus genome. The largest number of transcribed genes was in the stomach (n = 786); the next-largest numbers occurred in the cecum (n = 391) and the jejunum (n = 296), while only 26 Lactobacillus genes were transcribed in the colon. In vitro and in vivo transcription programs overlapped only partially. One hundred ninety-one of the transcripts from the lactobacilli in the stomach were not detected during in vitro growth; 202 and 213 genes, respectively, were transcribed under all in vitro and in vivo conditions; but the core transcriptome for all growth conditions comprised only 103 genes. Forty-four percent of the NCC533 genes were not detectably transcribed under any of the investigated conditions. Nontranscribed genes were clustered on the genome and enriched in the variable-genome part. Our data revealed not only major differences between in vitro- and in vivo-expressed genes in a Lactobacillus gut commensal organism but also marked changes in the expression of genes along the digestive tract.
对霍乱弧菌等病原体的研究表明，体外培养和体内生长的细菌所表达的基因存在重大差异。为了探究共生菌的这一问题，我们利用微阵列技术研究了约氏乳杆菌NCC533基因组在体外和体内生长过程中的转录情况。在肉汤培养过程中，1756个测试基因中分别有537个、626个和277个在指数期、“适应期”（早期稳定期）和稳定期表达。在这三个阶段分别有101个、150个和33个基因被特异性转录。为了探究体内转录程序，我们给经抗生素处理的小鼠投喂含有抗性质粒的约氏乳杆菌。经过2天的洗脱期后，我们测定了存在于不同肠道段管腔中以及与黏膜相关的乳杆菌的活菌数。虽然细胞计数显示沿肠道分布较为均匀，但我们观察到乳杆菌基因组的表达存在显著差异。转录基因数量最多的是胃（n = 786）；其次是盲肠（n = 391）和空肠（n = 296），而结肠中仅转录了26个乳杆菌基因。体外和体内转录程序仅部分重叠。胃中乳杆菌的191个转录本在体外生长过程中未被检测到；分别有202个和213个基因在所有体外和体内条件下均被转录；但所有生长条件下的核心转录组仅包含103个基因。在任何研究条件下，NCC533基因的44%均未被检测到转录。未转录的基因在基因组上成簇分布，且在可变基因组部分富集。我们的数据不仅揭示了肠道共生乳杆菌体外和体内表达基因之间的重大差异，还揭示了沿消化道基因表达的显著变化。
