Growth Temperature-Related Cell Surface Changes of Escherichia Coli O157:H-

ABSTRACT

Escherichia coli O157 is a foodborne pathogen. We have previously shown that when grown on agar at 37°C but not 20°C it is capable to attach to its surface a glycoconjugate that is reactive with the lectin concanavalin A (ConA) but is poorly recognized by specific antiserum. The aim of the present study is to check whether, and to what extent may such growth- temperature related ConA reactivity interfere with immunoreactivities of the bacterial population and of individual bacterial cells. The results show that there is no strict correlation between ConA reactivity and immunoreactivities of selected single colonies as revealed by immunofluorescence and immunogold for electron microscopy. One important observation was the pronounced cell-to-cell variability regarding access at the surface of immunoreactive sites. This may be due to several factors among which cell-to-cell differences in O157 lipopolysaccharide production dependent on individual cell growth, or differences in amounts of other surface components like the enterobacterial common antigen.

Keywords:

• Escherichia coli O157
• growth temperature
• immunofluorescence
• immunogold