Potential of endophytic bacteria from Acacia mearnsii: Phosphate solubilization, indole acetic acid production, and application in wheat

Agriculture, a historical pillar of civilizations, faces challenges due to population growth and climate change. Beneficial microorganisms can enhance agricultural resilience in these challenging scenarios. In particular, certain bacteria have the ability to solubilize phosphate and produce indole acetic acid (IAA), essential for plant growth. In this investigation, 215 strains of endophytic bacteria derived from active nodules of A. mearnsii were evaluated. The isolates were cultivated and assessed for their ability to solubilize phosphate and produce IAA. The analysis revealed that 120 of these strains (56 %) demonstrated phosphate solubilization potential under at least one of the tested temperature conditions, with 22 showing at least average solubilization according to pre-established parameters. The strains were also evaluated for IAA production, with strain A58 showing the highest production at a concentration of 89.2 μg mL−1. Of the 22 selected phosphate-solubilizing isolates, 7 had the 16S region sequenced, and it was possible to identify that these microorganisms belonged to the genera Serratia, Pseudomonas, and Stenotrophomonas. In greenhouse tests with wheat, it was observed that inoculation with certain isolated strains or in co-culture improved various plant growth parameters, indicating the practical implication of these findings for sustainable agriculture. In conclusion, the endophytes of Acacia mearnsii showed promising potential for agronomic applications, aiding in phosphate solubilization and IAA production, contributing to a more sustainable and productive agriculture. Further studies are needed to fully explore the potential of these microorganisms in real agricultural settings.