Screening of beneficial bacteria associated with Calophyllum brasiliense Cambess so as to develop microbial inoculants for agriculture

Beneficial bacteria belong to a group of microorganisms that are able to enhance plant growth by several mechanisms. In this study, phosphorus and zinc solubilizing, nitrogen-fixing and indole acetic acid (IAA) producing bacteria associated with C. brasiliensis were screened to develop microbial inoculants (MI) for use in agriculture. Characterization and identification of screened bacteria were also performed. A total of thirty-one nitrogen-fixing bacteria isolates were obtained, of which 28 showed the ability to solubilize phosphorus and 25 to solubilize zinc. The isolate AP-JNFb-3-2, belonging to the genus Pseudomonas, presented the highest value of solubilized phosphorus (100.4 µg mL-1). The isolates AP-JNFb-3-2 and RHI-JMVL-3-1, associated with the genera Pseudomonas and Enterobacter, respectively, showed the highest values for zinc solubilization (147.8 and 147.7 µg mL-1). Isolate RO-LGI.P-3-2, belonging to the genus Pseudomonas, was the most promising for IAA production (0.52 µg mL-1). The results obtained showed the presence of a large diversity of beneficial bacteria associated with C. brasiliensis, which may be explored as MI in agriculture.