Electrochemical detection of E. coli O157:H7 based on NaCl stress improving the bacterial electrocatalytic oxygen reduction performance

Firstly, through various analytical methods, the mechanism by which the electrocatalytic oxygen reduction capacity of E. coli O157:H7 was enhanced under 4% NaCl stress was revealed. The cyclic voltammetry (CV) results indicated that the oxygen reduction ability of E. coli O157: H7 was improved under NaCl stress. Microbiological analysis confirmed the intracellular ROS levels in E. coli O157: H7 under NaCl stress is related to the upregulation of SOD/CAT activity. Metabolomics identified key metabolic adaptations in E. coli O157:H7, including enhanced tricarboxylic acid (TCA) cycles and ubiquinone (Q) biosynthesis, which promoted effective respiratory electron transfer in the bacteria. Secondly, the BPE-ECL (Bipolar Electrochemiluminescence) sensor designed based on 4% NaCl stress showed 9.72 times increase in anode ECL intensity. The detection limit was extremely low at 10 CFU for E. coli O157:H7 in 1 mL sample volume. This research provides a new solution for the sensitive screening of electrochemically active bacteria.