Molecular analysis of the diversity of nitrogen-fixing and phosphate-solubilizing bacteria in Neltuma pallida (Humb. & Bonpl. ex Willd.) Kunth

García León M.F.; Cordova-Campos J.S.; Garcia-Garcia S.M.; Ruiz-Polo A.A.; Mialhe-Matonnier E.L.; García-Seminario R.; Mogollón-Farias C.A. · Scientia Agropecuaria (2026) · DOI: 10.17268/sci.agropecu.2026.045

Resumen

The identification of atmospheric nitrogen-fixing and phosphate-solubilizing bacteria emerges as a sustainable fertilization alternative to the use of agrochemicals that pollute the environment. The objective of this research was to molecularly analyze the diversity of nitrogen-fixing and phosphate-solubilizing bacteria in Neltuma pallida. Rhizospheric soil samples were collected from juvenile Neltuma pallida trees located in the practice field of the Forestry and Environmental Engineering program at the National University of Tumbes, in the locality of Garbanzal. Bacteria were isolated from the soil, morphologically characterized, and evaluated in nitrogen fixation assays by inoculating 5 μL of bacterial suspensions (1×10⁸ CFU/mL) in triplicate using ASHBY culture medium. Subsequently, isolates with the highest nitrogen fixation were selected for phosphate solubilization assays, which were inoculated into NBRIP medium supplemented with bromophenol blue (25 ppm), using the same bacterial concentration. Data analysis was performed using R Studio software. Finally, identification of the isolates was carried out by sequencing the 16S rRNA gene, and evolutionary relationships were established through a phylogenetic tree. In total, 50 bacterial strains were isolated, of which 41 had the ability to fix atmospheric nitrogen. Among these, 10 stood out for their high fixation efficiency and, of these, five also showed the ability to solubilize phosphate. However, only two strains exhibited high efficiency in both functions. Phylogenetic relationships grouped the species into three clades (Firmicutes, Proteobacteria, and Bacteroidetes). The species identified with dual capacity (nitrogen fixation and phosphate solubilization) were Bacillus megaterium, Erwinia spp., Bacillus flexus, Bacillus amyloliquefaciens, and Pantoea spp., whereas those that only fixed nitrogen included Bacillus endophyticus, Olivibacter spp., Pantoea septica, and Lysinibacillus xylanilyticus.

Instituciones: Universidad Nacional de Tumbes