VARIABLE EXPRESSION OF O-ANTIGEN AND THE ROLE OF LIPOPOLYSACCHARIDE AS AN ADHESIN IN AEROMONAS-SOBRIA

On initial isolation of Aeromonas sobria 3767 from a diarrhoeal stool specimen, two colony types were obtained: opaque (3767O) and transluce nt (3767T). Strain 3767O consistently produced lipopolysaccharide (LPS ) core and O-antigen side chain, detectable by SDS-PAGE and by Western blotting with an O-antigen-specific monoclonal antibody. Strain 3767T produced LPS core but the amount of O-antigen was dependent on factor s including growth medium and bacterial growth phase. Strain 3767T exh ibited significantly lower levels of adhesion to HEp-2 cells than 3767 O and this correlated with the level of LPS expression, with the great est reduction (61%) at stationary phase when no LPS was detectable. Th e results implicate LPS as an adhesin for A. sobria 3767.