Transcriptomic analysis by RNA-seq of Escherichia coli O157:H7 response to prolonged cold stress

The adaptability of Escherichia coli O157:H7 to different environmental stresses, including prolonged cold stress, poses a threat to food safety. In order to elucidate the prolonged cold response in E. coli O157:H7, genes related to prolonged coldresistance and their expression changes in E. coli O157:H7 ATCC35150 were screened and identified by analyzing their transcriptomedifferences between normal (37 °C) and low temperature storage (4 °C or −20 °C, 10 d), using RNA-sequencing. According to our results, 425 differentially expressed genes (DGEs) were identified responding to cold stresses in this study. Gene rpoS was significantly up-regulated (more than two fold; p < 0.05) and was referred to be the critical switch for the whole regulation in the response to prolonged cold stress. Moreover, cold shock genes played an important role only in the acclimation phase of E. coli O157:H7 in the early stage of cold stress, and were down-regulated in the adaptation stage. Specifically, E. coli O157:H7 would promote its resistance to prolonged cold stress mainly by increasing the expression of genes involved in the synthesis of unsaturated fatty acids and the accumulation of trehalose and betaine.