Inactivation Effect of Moderate-intensity Pulsed Electric Field on Escherichia coli and the Underlying Mechanism
Article
Figures
Metrics
Preview PDF
Reference
Related
Cited by
Materials
Abstract:
As a non-thermal sterilization method, pulsed electric field has been widely studied for its ability to control microbial contamination. The inactivation effects of moderate-intensity pulsed electric field (MIPEF) on Escherichia coli were clarified by using different media solutions (sodium chloride, phosphate-buffered saline, and peptone), mass fractions of sodium chloride (0.85%, 0.10%, 0.20%, and 0.30%), electric field intensities (0.16, 0.20, and 0.24 kV/cm), treatment times (20, 40, 60, 80, and 100 min), and bacterial densities (103, 105, 107, and 109). The morphological changes, intracellular macromolecules, and intracellular enzyme activities of E. coli treated with MIPEF were examined. The inactivation effect of MIPEF on E. coli differed under different conditions. The treatment time was positively correlated with the inactivation effect of MIPEF, and the microbial count was reduced by 3.08 lg CFU/mL after 100 min of treatment, with a temperature differential of 2.10 ℃. The bactericidal effect of MIPEF on E. coli was different in various media solutions. The inactivation effect of MIPEF on E. coli decreased significantly as the mass fraction of sodium chloride increased. MIPEF had a greater bactericidal effect when the bacterial density was lower. The results of field emission scanning electron microscopy and transmission electron microscopy demonstrated that cell integrity was compromised following MIPEF treatment. Macromolecular constituents, including proteins and DNA, were significantly reduced following MIPEF treatment. Furthermore, the activities of adenosine triphosphatase (ATPase), succinate dehydrogenase (SDH), and pyruvate kinase (PK) were significantly diminished (P<0.05) in the samples treated with MIPEF for 100 min compared with those in control samples. Furthermore, the activities of Na+K+-ATPase, Ca2+Mg2+-ATPase, and SDH were reduced by 34.21%, 32.26%, and 86.93%, respectively, whereas the activity of PK was reduced by 88.93 U/g prot. This study provides a reference for application of non-thermal sterilization technology in the food industry and clarifies the sterilization mechanism of MIPEF.
