THE INFLUENCE OF A-BAND AND B-BAND LIPOPOLYSACCHARIDE ON THE SURFACE CHARACTERISTICS AND ADHESION OF PSEUDOMONAS-AERUGINOSA TO SURFACES

Pseudomonas aeruginosa PAO1 possesses two distinct lipopolysaccharide (LPS) O-polysaccharide species, A- and B-band LPS, the relative expres sion of which appears to be under environmental control. In an attempt to identify the influence these LPS types have on surface characteris tics and adhesion, we examined the surface hydrophobicity and surface charge of P. aeruginosa PAO1 (O5 serotype) and its isogenic LPS deriva tives which possessed A(+)B(-), A(-)B(+) and A(-)B(-) LPS. The surface characteristics of the strains affected their ability to adhere to hy drophilic (glass) and hydrophobic (polystyrene) surfaces. Cells posses sing only A-band LPS demonstrated the highest surface hydrophobicity, followed by the strain lacking both A- and B-band LPS. the presence of B-band LPS resulted in a more hydrophilic surface. Strains lacking B- band LPS (A(+)B- and A(-)B(-)) had more electronegative surfaces than those possessing B-band LPS (A(+)B(+) and A(-)B(+)), with cells lackin g both A- and B-band LPS showing the highest surface electronegativity . These data suggest that the main surface-charge-determining groups r eside in the core region of the LPS molecule. Cells with the lowest su rface hydrophobicity and lowest surface charge (A(+)B(+), A(-)B(+)) ad hered to glass the most efficiently, implying a role for electrostatic interaction, whereas adhesion to polystyrene mirrored the relative hy drophobicities of the strains (A(+)B(-) > A(-)B(-) > A(+)B(+) > A(-)B( +)). It is postulated that phenotypic variation in the relative expres sion of A- and B-band LPS may be a mechanism by which P. aeruginosa ca n alter its overall surface characteristics in such a way as to influe nce adhesion and favour survival.