Promotion of the Synthesis of a Concanavalin A-reactive Polysaccharide Upon Growth of Escherichia coli O157:H(-) on Solid Medium at 37°C

The polysaccharides exposed at the bacterial surface are involved in many processes related with the interaction of microorganisms with their environments, outside or inside the mammalian host. The aim of this study was to test the effects of growth temperatures (20oC and 37oC) on some characteristics of the surface polysaccharides of E. coli O157:H(-). The glycoconjugates were isolated by hot phenol-water extraction. The tests included ELISA, ELLA, immunoelectrophoresis (classical, or modified for application with concanavalin A /ConA/) and Western blot. It was shown that the water-phase fraction of the strain cultivated at 37oC was distinctive among the compared samples. It was poorly recognized by specific anti-E. coli O157 antiserum but, contrary to all the other fractions, interacted well with the lectin, ConA. A similar ConA-reactivity was demonstrated for the purified cyclic enterobacterial common antigen (ECACYC4). This implies that the ConA reactivity may likely be due to ECACYC. The promotion of the release of this ConA-reactive entity at 37oC, i.e., the temperature condition characteristic for host body, indicates its importance in the host-invader interplay.