Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark.
Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark.
Int J Food Microbiol. 2016 May 2;224:40-6. doi: 10.1016/j.ijfoodmicro.2016.02.015. Epub 2016 Feb 24.
Salmonella enterica serovar Enteritidis (S. Enteritidis) is the most common cause of egg borne salmonellosis in many parts of the world. This study analyzed gene expression of this bacterium during growth in whole egg, and whether highly expressed genes were essential for the growth. High quality RNA was extracted from S. Enteritidis using a modified RNA-extraction protocol. Global gene expression during growth in whole egg was compared to growth in LB-medium using DNA array method. Twenty-six genes were significantly upregulated during growth in egg; these belonged to amino acid biosynthesis, di/oligopeptide transport system, biotin synthesis, ferrous iron transport system, and type III secretion system. Significant downregulation of 15 genes related to formate hydrogenlyase (FHL) and trehalose metabolism was observed. The results suggested that S. Enteritidis is starved for amino-acids, biotin and iron when growing in egg. However, site specific mutation of amino acid biosynthesis genes asnA (17.3 fold upregulated), asnB (18.6 fold upregulated), asnA/asnB and, serA (12.0 fold upregulated) and gdhA (3.7 fold upregulated), did not result in growth attenuation, suggesting that biosynthesis using the enzymes encoded from these genes may represent the first choice for S. Enteritidis when growing in egg, but when absent, the bacterium could use alternative ways to obtain the amino acids.
肠炎沙门氏菌血清型肠炎（S. Enteritidis）是世界许多地区鸡蛋传播沙门氏菌病的最常见原因。本研究分析了该细菌在全蛋液中生长过程中的基因表达情况，以及高表达基因是否对生长至关重要。使用改良的 RNA 提取方案从 S. Enteritidis 中提取高质量的 RNA。使用 DNA 芯片方法比较了在全蛋液和 LB 培养基中生长时的全基因表达情况。在鸡蛋中生长时，有 26 个基因显著上调；这些基因属于氨基酸生物合成、二/寡肽运输系统、生物素合成、亚铁运输系统和 III 型分泌系统。观察到与甲酸氢酶（FHL）和海藻糖代谢相关的 15 个基因显著下调。结果表明，S. Enteritidis 在鸡蛋中生长时会出现氨基酸、生物素和铁饥饿。然而，对氨基酸生物合成基因 asnA（上调 17.3 倍）、asnB（上调 18.6 倍）、asnA/asnB 和 serA（上调 12.0 倍）和 gdhA（上调 3.7 倍）进行定点突变并未导致生长减弱，这表明使用这些基因编码的酶进行生物合成可能是 S. Enteritidis 在鸡蛋中生长的首选，但当这些基因不存在时，细菌可以使用替代方法获取氨基酸。
