Characterization of Rhizobacteria Associated with Vitis vinifera and Its Interaction in vitro with Entomopathogenic Fungi

The rhizosphere is a zone of unique and dynamic interactions between plant roots and soil microorganisms, which can influence the nutrition and stress tolerance of the plant. Among the microorganisms that colonize the roots of plants, bacteria, fungi, protozoa and algae can be found; within these, we can find growth promoting rhizobacteria and entomopathogenic fungi. Although there are studies of these groups of microorganisms that co-inhabit the rhizosphere, showing that the interaction of entomopathogenic fungi along with growth promoting rhizobacteria, when used combined, can provide greater protection to the plants. Nonetheless, these interactions have not been studied in depth. Thus, the objective of this study was the characterization of rhizobacteria and the evaluation of the antagonism in vitro with entomopathogenic fungi. In our study, bacteria native to the rhizosphere of Vitis vinifera were isolated and characterized in vitro, in order to determine their potential to promote plant growth; in addition, in vitro antagonism was determined with entomopathogenic fungi isolated from the same site. Some strains showed potential to promote plant growth, standing out Chryseobacterium sp., especially for its potential to fix atmospheric nitrogen, siderophores and indolacetic acid production. On the other hand, no antagonism was shown between bacterial strains; however, when confronted with entomopathogenic fungi, inhibition of area growth of Beauveria pseudobassiana was observed by most bacteria, while in Metarhizium anisopliae, only by Bacillus solani (CB1) and Pseudomonas montelii (CP1).