Division of Food Processing Science and Technology, U.S. Food and Drug Administration, Bedford Park, Illinois 60501, USA.
Foodborne Pathog Dis. 2012 Dec;9(12):1143-51. doi: 10.1089/fpd.2012.1254.
The survival of Salmonella in low moisture foods and processing environments remains a great challenge for the food industry and public health. To explore the mechanisms of Salmonella desiccation resistance, we studied the transcriptomic responses in Salmonella Tennessee (Tennessee), using Salmonella Typhimurium LT2 (LT2), a strain weakly resistant to desiccation, as a reference strain. In response to 2 h of air-drying at 11% equilibrated relative humidity, approximately one-fourth of the open reading frames (ORFs) in the Tennessee genome and one-fifth in LT2 were differentially expressed (>2-fold). Among all differentially expressed functional groups (>5-fold) in both strains, the expression fold change associated with fatty acid metabolism was the highest, and constituted 51% and 35% of the total expression fold change in Tennessee and LT2, respectively. Tennessee showed greater changes in expression of genes associated with stress response and envelope modification than LT2, while showing lesser changes in protein biosynthesis expression. Expression of flagella genes was significantly more inhibited in stationary phase cells of Tennessee than LT2 both before and after desiccation. The accumulation of the osmolyte trehalose was significantly induced by desiccation in Tennessee, but no increase was detectable in LT2, which is consistent with the expression patterns of the entire trehalose biosynthesis and degradation pathways in both strains. Results from this study present a global view of the dynamic desiccation responses in Salmonella, which will guide future research efforts to control Salmonella in low moisture environments.
沙门氏菌在低水分食品和加工环境中的存活仍然是食品工业和公共卫生的一大挑战。为了探索沙门氏菌干燥抗性的机制，我们研究了沙门氏菌田纳西州（Tennessee）的转录组反应，以沙门氏菌 Typhimurium LT2（LT2）作为参考菌株，该菌株对干燥的抵抗力较弱。在 11%相对湿度平衡条件下空气干燥 2 小时后，田纳西州基因组中约四分之一的开放阅读框（ORF）和 LT2 中的五分之一的 ORF 表达差异（>2 倍）。在两种菌株中所有差异表达的功能组（>5 倍）中，与脂肪酸代谢相关的表达倍数变化最高，分别占田纳西州和 LT2 总表达倍数变化的 51%和 35%。与 LT2 相比，田纳西州表现出与应激反应和包膜修饰相关的基因表达变化更大，而蛋白质生物合成表达的变化较小。与 LT2 相比，田纳西州的静止期细胞中 flagella 基因的表达在干燥前和干燥后均受到显著抑制。在田纳西州，干燥可显著诱导渗透物海藻糖的积累，但在 LT2 中则检测不到增加，这与两种菌株中海藻糖生物合成和降解途径的整个表达模式一致。本研究的结果提供了沙门氏菌干燥反应的整体动态视图，这将指导未来控制低水分环境中沙门氏菌的研究工作。
