Abstract: With the increasingly severe situation of bacterial drug resistance in the world,bacterial drug-resistant mechanism has become a hot topic. An iTRAQ-labeling-based quantitative proteomics method was performed to compare the differential expression of Escherichia coli K12 BW25113 in response to 1/4MIC balofloxacin stress. The result showed that a total of 118 differential proteins with 66 down-regulated and 52 up-regulated ones were identified. Bioinformatics analysis further showed that bacterial drug-resistances were regulated by altering some energy metabolism such as reducing TCA cycle,pyruvate cycle,and carbon,and bacterial survival increased by rising the expressions of proteins related to nucleic acid metabolism and then eliminating the stresses from blofloxacin. Meanwhile,the qPCR method was used to validate the differential expressions of genes related to the carbon metabolism and pyrimidine metabolism;consequently,most of the transcription levels of these genes were consistent with their protein levels. These findings provide the theoretical basis for further investigating the bacterial drug resistance process and action targets for better controlling and treating drug-resistant bacteria.

Key words: Escherichia coli, blofloxacin, stress resistance, quantitative proteomics