Comparative genomics and metabolomics reveal phytohormone production, nutrient acquisition, and osmotic stress tolerance in Azotobacter chroococcum W5

Elakkya Muthu¹Luz Angela Gonzalez²Karina López-Reyes²Inês Rebelo-Romão³André Sousa³Victoria Gödde⁴Karsten Niehaus⁴Dhivya Thennappan^1,5Juan Ignacio Vilchez Morillas^3*Sangeeta Paul^1*Cuauhtemoc Licona-Cassani^6*

• ¹Division of Microbiology, ICAR-Indian Agricultural Research Institute, Delhi, India
• ²Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Monterrey, Mexico
• ³Instituto de Tecnologia Química e Biológica (ITQB)-NOVA, Lisboa, Portugal
• ⁴Proteom-und Metabolomforschung, Fakultät für Biologie, Centrum für Biotechnologie, Universität Bielefeld, Bielefeld, Germany
• ⁵Systems Plant Physiology, Texas A&M AgriLife Research and Extension Center, Uvalde, Texas, United States
• ⁶Monterrey Institute of Technology and Higher Education (ITESM), Monterrey, Mexico

Concerns about ecological degradation and reduced biodiversity have intensified the search for sustainable solutions in agriculture. The use of plant growth-promoting bacteria (PGPB) offers a promising alternative to enhance soil quality and crop yield while reducing the consumption of chemical fertilizers. Here, we characterize the plant growth-promoting potential of Azotobacter chroococcum W5 through comparative genomics, in vitro experiments, and metabolomic analyses. Comparative genomic analysis revealed plant growth-promoting traits, including phytohormone biosynthesis, nutrient acquisition, stress adaptation, and colonization in the A. chroococcum W5 strain. Experimental assays confirmed the production of auxin, gibberellic acid, phosphate solubilization, moderate nitrogen fixation, and growth on ACC. Wheat seed inoculation significantly enhanced germination metrics, seedling vigor, and altered carbohydrate metabolism in the seed endosperm. Under salt and osmotic stress, A. chroococcum W5 metabolomic profiling revealed adaptive responses, including elevated levels of osmoprotectants (proline, glycerol) and oxidative stress markers such as 2-hydroxyglutarate, while putrescine and glycine decreased. Our results show that the A. chroococcum W5 strain has great potential for the development of novel formulations. More importantly, our results highlight the potential of using plant growth-promoting microorganisms for innovative, sustainable solutions in agriculture.