IMPROVEMENT OF THE IMMUNOMAGNETIC SEPARATION METHOD SELECTIVE FOR ESCHERICHIA-COLI O157 STRAINS

Immunomagnetic separation is a useful enrichment method selective for Escherichia coli 0157 cells against non-0157 E. coli cells from a pree nrichment culture. However, E. coli cells are adsorbed onto a solid su rface nonspecifically. With the conventional immunomagnetic separation method, this nonspecific adsorption interfered with immunomagnetic se paration. It was found that this interference could be reduced with a low-ionic-strength solution. When immunomagnetic separation was carrie d out with this solution, the proportion of E. coli 0157 cells to non- 0157 E. coli cells increased from 9.6 to 31.4 times compared to the pr oportion obtained by the conventional immunomagnetic separation method . The effectiveness of this solution was successfully evaluated by the use of E. coli 0157-spiked samples.