Characterization of cell surface components of Azospirillum brasilense Sp7 as antigenic determinants for strain-specific monoclonal antibodies

Monoclonal antibodies (mAbs) with high specificity for Azospirillum brasilense Sp7, and which bind to different antigenic determinants, were characterized using Western blot techniques applied to one- and two-dimensional fingerprints of the outer-membrane components, and by immunogold labelling combined with transmission electron microscopy. One class of mAbs, which bound to A. brasilense Sp7 and the closely related strain Cd, recognized a 100 kDa protein subunit of the polar flagellum. Two classes of strain-specific mAbs for A. brasilense Sp7 bound, respectively, to a 85 kDa outer-membrane protein and to polysaccharide.