Proteomics, Metabolomics and Docking Analyses Provide Insights into Adaptation Strategies of Staphylococcus warneri CPD1 to Osmotic Stress and Its Influence on Wheat Growth

Staphylococcus warneri is a gram-positive mesophilic bacterium, resilient to extreme environmental conditions. To unravel its Osmotic Tolerance Response (OTR), we conducted proteomic and metabolomic analyses under drought (PEG) and salt (NaCl) stresses. Our findings revealed 1340 differentially expressed proteins (DEPs) across all treatments. Interestingly, majority of these DEPs were part of common pathways activated by S. warneri. CPD1 in response to osmotic stress. Notably, the bacterial isolate exhibited increased expression of lysophospholipases associated with biofilm formation and protection from environmental stresses, transglycosylases involved in peptidoglycan biosynthesis, and acetoin reductase linked to acetoin metabolism. The upregulation of global ion transporters, including ABC transporters, potassium ion transport, and glutamate transport, indicated the bacterium's ability to maintain ionic balance under stress conditions. Protein-protein docking analysis revealed highest interactions with thioredoxin and alpha-acetolactate decarboxylase, highlighting their crucial roles in the mechanisms of osmotic stress tolerance in S. warneri CPD1. Metabolomic results demonstrated significant alterations in fatty acids and amino acids. In the greenhouse experiment, the bacterial isolate significantly enhanced wheat biomass, nutrient content, photosynthesis, and proline levels under stress conditions, making it a promising bacterial inoculant and biostimulant for improving crop productivity in challenging environments.