Andean Rhizospheric Microorganisms as Plant Growth-promoting Platforms: Characterization of Pseudomonas Protegens M2 and Bacillus Proteolyticus M9

The rhizosphere of Andean crops constitutes a unique reservoir of microorganisms with biotechnological potential for boosting plant development and phytopathogen control. In this study, the functional capacities of two microbial strains isolated from Andean tubers were evaluated: Pseudomonas protegens M2, from the rhizosphere of oca (Oxalis tuberosa), and Bacillus proteolyticus M9, isolated from the rhizosphere of mashua (Tropaeolum tuberosum). Their molecular identity was confirmed by alignment of the 16S ribosomal marker gene. Strain M2 displayed an outstanding multifunctional profile, with nitrogen-fixing activity, siderophore production, inorganic phosphate solubilization (5.06 ± 0.75 HD/CD ratio), and elevated indoleacetic acid synthesis (60.66 ± 0.44 µg/mL). Furthermore, it exhibited a high antagonistic capacity against Fusarium oxysporum (51.29 ± 0.73%) and Rhizoctonia sp. (59.89 ± 1.11%). In contrast, M9 showed limited behavior, lacking IAA production or antifungal activity. These results position P. protegens M2 as a promising microorganism for the development of biological fertilizers and microbial antagonists, promoting eco-friendly agriculture, especially in regions vulnerable to climate change.