[Study of immunochemical heterogeneity of Azospirillum brasilense lipopolysaccharides]

A comparative immunochemical analysis of lipopolysaccharides (LPS) in Azospirillum brasilense model strains Sp7 and Sp245 and in mutants with transformed somatic antigens has been performed. According to the results of a complex of various immunochemical methods, including studies with polyclonal antibodies against the LPS these bacteria, their LPS consist of an assembly of macromolecules with different antigenic characteristics. Two types of O-specific polysaccharides (O-PS) are present in the LPS of every strain of A. brasilense under study. The major difference between the two O-PS is the antigenic heterogeneity of one of them. This heterogeneous O-PS has been shown to possess at least two O-factors (antigenic determinants) different in their structure. Meanwhile, according to all the tests performed, the other O-PS in every strain is immunochemically homogeneous and identical to one of the determinants revealed in the more diversified O-PS. The LPS heterogeneity among the given strains may be due to the pattern of O-specific polysaccharide synthesis, one of the O-PS being an intermediate in the synthesis of the other.