Characterization of Carbohydrate-Containing Components of Azospirillum brasilense Sp245 Biofilms

The structure and functions of the biopolymers of the matrix of Azospirillum brasilense biofilms formed at the liquid–solid interface were studied. Calcofluor-binding polysaccharides (CBPS) and the complexes containing lipopolysaccharides (LPS) and proteinaceous structures were shown to fix mature biofilms on solid surfaces and to perform a framework function. The matrix of mature biofilms contained a carbohydrate hapten with a specific affinity to wheat germ agglutinin (WGA), which is important for associative interaction and plant root colonization. The carbohydrate components, predominating over the proteinaceous matrix components, mediate preferable biofilm attachment to hydrophilic surfaces, which is especially evident in the case of A. brasilense Sp245 mutants with impaired flagella formation. This is the first report on the presence of amyloid structures in the biomass of Azospirillum biofilms.