Changes in cell surface properties of shiga toxigenic escherichia coli by quercus infectoria g. olivier

Abstract

The effects of Quercus infectoria (family Fagaceae) nutgalls on cell surface properties of Shiga toxigenic Escherichia coli (STEC) were investigated with an assay of microbial adhesion to hydrocarbon. The surface of bacterial cells treated with Q. infectoria exhibited a higher level of cell surface hydrophobicity (CSH) toward toluene than did the surface of untreated cells. With 50% ethanolic extract, the CSH of the three strains of STEC 0157:H7 treated with 4X MIC of the extract resulted in moderate or strong hydrophobicity, whereas at 2X MIC and MIC, the CSH of only one strain of E. coli 0157:H7 was significantly affected. The 95% ethanolic extract had a significant effect on CSH of all three strains at both 4X MIC and 2X MIC but not at the MIC. The effect on bacterial CSH was less pronounced with the other STEC strains. At 4X MIC, the 50% ethanolic extract increased the CSH of all non-0157 STEC strains significantly. At 2X MIC and 4X MIC, the 95% ethanolic extract affected the CSH of E. coli 026:H11 significantly but did not affect E. coli Ol 11 :NM or E. coli 022. Electron microscopic examination revealed the loss of pili in the treated cells. The ability of Q. infectoria extract to modify hydrophobic domains enables this extract to partition the lipids of the bacterial cell membrane, rendering the membrane more permeable and allowing leakage of ions and other cell contents, which leads to cell death. Further studies are required to evaluate the effects of Q. infectoria extract in food systems or in vivo and provide support for the use of this extract as a food additive for control of these STEC pathogens. Copyright ©, International Association for Food Protection.