Serological differentiation of Azospirillum species belonging to different host-plant specificity groups

Abstract

The results of the cross reactions of the 27 strains of Azospirillum spp. with 4 fluorescent antibodies (FA) show a neat differentiation between the two species. A. lipoferum represents a more homogenous group in respect to FA reactions and highly fluorescent preparations were obtained with strains from a large scope origin against Sp59 FA, the type strain. In contrast A. brasilense contains at least three sub groups in respect to FA reactions. The first includes all denitrifing strains (nir+) which react with FA from Sp7 the type strain. None of the nir- strains reacted strongly with Sp7 FA. One part of the A. brasilense nir- group which includes the strains isolated from well sterilized rice and wheat roots (Sp 107, 107 st, 106 and 109 st) reacts with FA of their reference strain Sp107 but not with that of Sp28 FA. The strains isolated from unsterilized roots and soils reacted with SP28 FA and not with that of Sp107 FA. In addition there were 3 strains (Sp A4, 34 and 67) which reacted with neither of the FAs.