Isolation and Functional Characterization of Plant Growth-Promoting Bacteria Associated with Peanut (Arachis hypogaea L.) Cultivation, Revealed by 16S rRNA Sequencing and BOX-PCR

Soil is a dynamic ecosystem rich in microorganisms that play essential roles in plant health, nutrient cycling, and organic matter decomposition. In Brazil, peanut ( Arachis hypogaea L.) cultivation is concentrated in the state of São Paulo, where crop rotation systems contribute to soil conservation, increased fertility, and erosion control. Through symbiosis with microorganisms such as Rhizobium , peanut enhances nutrient acquisition and plant development, thereby reducing dependence on chemical fertilizers. Despite its agronomic relevance, information on the taxonomic and functional diversity of microorganisms associated with peanut cultivation remains limited. This study aimed to isolate, characterize, and select microorganisms with potential to promote peanut growth and nutrition. Samples of nodules, roots, and soil were collected during the dry and rainy seasons. A total of 92 bacterial isolates were obtained and qualitatively evaluated for indole-3-acetic acid (IAA) production, phosphate solubilization, and siderophore production. Selected strains were subjected to IAA quantification and molecular identification by 16S rRNA gene sequencing. Genomic diversity was analyzed using BOX-PCR. High variability in plant growth-promoting traits was observed. The best-performing isolates were selected to establish a collection of promising strains for future in planta and field studies. This integrated approach improves understanding of the soil microbiota associated with peanut and supports the development of more sustainable agricultural strategies.