Location: Produce Safety and Microbiology ResearchTitle: Disruption the Outer Membrane of Enteropathogenic and Enterotoxigenic Escherichia coli using Proanthocyanidins
|SHAIBANI, DHAFER AL - University Of Maine|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/18/2017
Publication Date: N/A
Technical Abstract: American cranberry (Vaccinium macrocarpon) proanthocyanidins (PACs) have been reported as a natural antibacterial agent to suppress the growth of pathogenic Escherichia coli. The objective of this study was to investigate the efficacy of cranberry-derived proanthocyanidins on destabilizing the outer membrane of Enteropathogenic (EPEC) and Enterotoxigenic (ETEC) E. coli, which are the causative agents of infantile and traveler’s diarrhea, respectively. The cell membrane permeability of ETEC strain, E. coli O78:H11 H10407 and EPEC strain, E. coli O127:H6 E2348/69 was detected by LIVE/DEAD viability assay. Each strain was grown overnight at 37'C in 10 ml of BHI broth. PACs concentrations (0.9, 1.8, 2.7, 3.6 and 7.2 mg/ml) were prepared in 10 ml of sterile 0.85% NaCl. One milliliter of 9-log CFU/ml of E. coli strain was added to each PACs concentration and incubated for 1h at 25'C. The membrane permeability was then detected by the uptake of propidium iodide (PI) after incubating the treated E. coli with nucleic acid stains. Transmission electron microscopy (TEM) was used to examine the integrity of the outer membrane after both strains were treated with 3.6 mg/ml of PACs in 0.85% NaCl for 20 min at 2'C. Analysis of variance (ANOVA) was performed using JMP 13 software for mean separation and Tukey’s Honest Squared Difference (HSD) used to determine the differences among treatments. The results showed that there was a significant (p < 0.05) increase in the uptake of PI after E. coli O78:H11 H10407 and E. coli O127:H6 E2348/69 were treated with 3.6 mg/ml of PACs due to the increase of cell membrane permeability of tested E. coli. TEM micrographs confirmed the disruption of bacterial cells as observed in the outer membrane damage and leakage of the intracellular components in the PACs treated cells compared to the control. This is the first study that illustrates the inhibitory effect of cranberry-derived proanthocyanidins by damaging the outer membrane of Enteropathogenic (EPEC) and Enterotoxigenic (ETEC) E. coli, which are the major causative agents of diarrhea in children under 5 years old and traveler’s. Therefore; PACs may have protective action to prevent diarrhea.