Immunocytochemical characterisation of endophytic bacteria Azospirillum brasilense, Herbaspirillum seropedicae, Burkholderia ambifaria and Gluconacetobacter diazotrophicus

In the present work an immunocytochemical characterisation of four endophytic bacterial species has been made by using polyclonal antiserum produced against each of the four bacterial strains previously heated at 60 degrees C. The aim of this research is to identify common elements among bacteria associated with their endophytic behaviour. Analysis of extracts of each strain by immunoblotting and ELISA confirmed the presence of proteins from different bacterial strains made up of common epitopes. However, antisera produced against Herbaspirillum seropedicae and Burkholderia ambifaria show a high number of bands recognised on each extracts, while antisera against Azospirillum brasilense and Gluconacetobacter diazotrophicus show a low number of bands recognised on each extract. Immunogold labelling showed that epitopes are located both on the cell wall and in the cytoplasm; most likely they could be precursor cell wall proteins synthesized inside the cytoplasm and subsequently transported onto cell wall. Finally, the common bands among bacterial strains revealed by immunoblotting could play a role as active hydrolases involved in host tissue penetration.