A Preliminary Investigation on the Chemical Composition of the Cell Surface of Five Enteropathogenic Escherichia coli Serotypes

Abstract

The cell surfaces of five enteropathogenic Escherichia coli serotypes (O111:H2; O111:H12; O125:H9; O119:H6; O26:H11) were assayed by chemical methods, lectin agglutination tests and spectroscopy associated to transmission electron microscopy. Results of lectin agglutination assays showed that all strains reacted with mannose-binding lectins. Strains belonging to serotype OI25:H9 also agglutinated with lectins which recognize galactose and N-acetyl-galactosamine residues. The bacterial cells were treated with 0.01M phosphate buffered saline (pH 7.0) at 100° C for 2 hr and the extracts were submitted to precipitation and fractionated by Cetavlon. Phosphate, total sugar and protein contents were determined. Gas liquid chomatography-mass spectrometry analysis of alditol acetates showed the presence of galactose, mannose, fucose, glucose and traces of ribose. Spectroscopic analysis of intact cells showed the presence of a capsule-like structure which was not totally preserved after extraction. Some cells were still surrounded by an amorphous capsular-like material after polysaccharide extraction.