Evaluation of the membrane damage mechanism of chlorogenic acid against Bacillus cereus and Micrococcus luteus a simulation study on antibacterial growth in food

This study aimed to examine the mechanism of membrane damage by chlorogenic acid (CA) on Bacillus cereus and Micrococcus luteus and to apply it to milk and pork to evaluate whether CA could prolong their shelf life. A broth microdilution method was used to determine the minimum inhibitory concentration (MIC) of CA on B. cereus and M. luteus. In addition, the physiological changes and morphology of B. cereus and M. luteus after CA treatment were explored using membrane potential, intracellular ATP concentration, confocal laser scanning microscopy, and field emission gun scanning electron microscopy (FEG-SEM). The results showed that the MIC value of CA on both B. cereus and M. luteus was 2.5 mg/ml. The abnormal changes in membrane potential and the decrease of intracellular ATP concentration indicated that CA affected the membrane integrity of B. cereus and M. luteus. Observation by FEG-SEM showed that CA ruptured the cell membrane of B. cereus and M. luteus, causing the contents to flow out, and giving the cells a concave morphology. Finally, growth inhibition models of CA on B. cereus in skim milk and M. luteus in pork were developed using response surface methodology. The results demonstrated that 2.5 mg/ml of CA significantly inhibited the growth of B. cereus in skim milk and of M. luteus in pork. Therefore, CA can be used as a natural antimicrobial agent to prolong the shelf life of milk and pork.