Bacillus altitudinis GG-22: A Novel Plant Growth-Promoting Bacterium with Beneficial Agronomic Properties

Bacillus altitudinis GG-22, isolated from the phyllosphere of agricultural crops, has been identified as a promising biocontrol agent and plant growth-promoting bacterium with substantial potential in sustainable agriculture. In this study, in vitro antagonism assays demonstrated significant inhibitory effects against phytopathogenic fungi and oomycetes, such as Verticillium dahliae and Pythium sp., though GG-22 showed limited efficacy against bacterial pathogens, including Xylella fastidiosa. Transcriptomic profiling of olive trees treated with GG-22 indicated early activation of auxin transport and systemic acquired resistance (SAR) pathways, alongside substantial downregulation of cell wall remodeling genes. These findings suggest that GG-22 not only primes plant defense responses but also modulates hormonal pathways critical for growth and stress resilience. Future research should prioritize optimizing application strategies and exploring synergies with other microbial agents to fully harness the biocontrol and growth-promoting potential of GG-22. This strain holds promise for sustainable agricultural practices, particularly in managing fungal diseases and improving plant performance under stress conditions.