In this case, the bacteria compete for space at the root of pathogens, where they produce chelators (so-called siderophores) which are specific for the Fe3+ ions. Siderophores have a higher affinity for iron than chelators produced by pathogenic microorganisms present in the rhizosphere. Thus, the Fe3+ becomes unavailable for pathogens. PGPR bacteria are also capable of the production of secondary metabolites with antibiotic properties or are antifungal substances, insecticides and immunosuppressants (Glick, 2005).