Genome Characterisation of <i>Priestia megaterium</i> mj1212 and Its Synergistic Effect With N‐Acetylglucosamine in Enhancing Soybean Salt Stress Tolerance

As a sustainable alternative to inorganic fertilisers, the combined application of plant-growth promoting microbes and organic amendments offers an efficient biological approach to enhance plant growth under stress conditions. In this study, we present the complete genome sequence and functional annotation of the soil bacterial strain Priestia megaterium mj1212 (formerly classified as Bacillus megaterium), supporting its recent taxonomic reclassification and revealing its potential for secondary metabolites production, plant growth promotion, and adoption to environmental stresses. Our results showed that the combined application of N-acetylglucosamine (GlcNAc) and mj1212 exhibited a synergistic effect, significantly increasing the length and weight of soybean shoots and roots by up to 24.36% and 42.22%, and 10.95% and 14.51%, respectively, under 150 mM NaCl stress. In addition, both sole and combined treatments of GlcNAc and mj1212 significantly enhanced root nodules formation, photosynthetic parameters, and relative water contents. Similarly, the individual and combined treatments of GlcNAc and mj1212 significantly increased polyphenol oxidase and flavonoid content, while reducing superoxide oxidase and catalase (CAT) activities. Organic acids analysis revealed increased levels of citric acids, and malic acids, while succinic acids and lactic acids levels decreased significantly under both conditions, with a slight antagonistic effect observed under stress. Notably, nitric oxide (SNO) levels, which decreased by 60.59% under NaCl stress, were restored by 492.55% of the stress level (nM/µg) with the combined treatment of GlcNAc and mj1212. The findings also suggested that GlcNAc and mj1212 treatments could improve soybean tolerance to salt stress by modulating abscisic acids biosynthesis. These findings underscore the potential of mj1212 and GlcNAc as effective biofertilizers for enhancing salt stress tolerance and promoting sustainable crop growth.