Specific agglutination of Escherichia coli O₁₂₈B₁₂ by the mannose-binding proteins of Pseudomonas aeruginosa

The mannosephilic haemagglutinins of P. aeruginosa were found to agglutinate cells of E. coli O₁₂₈B₁₂, to be adsorbed on to them and to attach peroxidase to them. These reactions were specifically inhibited by D-mannose. No agglutination by this Pseudomonas haemagglutinin was obtained when several other enteropathogenic types of E.coli and some other Gram-negative bacteria were examined. Concanavalin A, which also reacted with E.coli O₁₂₈B₁₂ cells, interacted with some of the other bacteria examined, too. E.coli O₁₂₈B₁₂ was not agglutinated by the P.galactosephilic haemagglutinins and those of the plant Phaseolus vulgaris. Its maximal agglutination by the Pseudomonas mannosephilic haemagglutinins was obtained employing cells grown for 4-6 h in conventional media. The growth temperature, aeration and presence of certain amino acids, but not D-mannose, in the culture medium had some effect on the agglutination intensity; pH 6-8 was optimal for it and only at pH 3.0-3.2 no agglutination was observed. Treatment of the bacteria by proteolytic enzymes, ethanol or formaldehyde did not alter their agglutinability by either the Pseudomonas lectin or by antibodies produced against them in rabbits. Heating of the bacteria to 100°C prevented their agglutination by the Pseudomonas lectin and lowered their ability to adsorb it, but did not significantly affect their reactions with the rabbit antibodies.