Microbial Dream Team: Cotton Performs Better in Salty Soil with Pseudomonas hunanensis RT-12 and Staphylococcus caprae DS-2.

Salinity is a major abiotic constraint that limits crop productivity, particularly in salt-affected soils. This study explores the synergistic potential of two rhizosphere-derived bacterial strains, Staphylococcus caprae DS-2 and Pseudomonas hunanensis RT-12, in enhancing salinity tolerance in Gossypium hirsutum (cotton). Both isolates exhibited notable halotolerance and multiple plant growth improving traits, including indole-3-acetic acid biosynthesis, phosphate solubilization, ammonia and siderophore production, catalase and protease activity, and hydrogen cyanide production. Molecular identification using 16 S rRNA gene sequencing confirmed their taxonomic placement. A controlled pot experiment under 200 mM NaCl stress was conducted to evaluate their individual and combined effects on plant performance. Co-inoculation markedly improved growth parameters (shoot length, roots length, fresh weights (g) of roots and shoots, dry weights (g) of roots and shoots, and number of leaves) and chlorophyll content compared to single-strain treatments and uninoculated controls. This enhancement correlated with elevated antioxidant enzyme activities (superoxide dismutase and peroxidase), increased proline accumulation, and reduced levels of malondialdehyde and hydrogen peroxide, indicating improved oxidative stress management. Notably, the dual-strain inoculation more effectively promoted osmotic adjustment, ionic balance, and redox homeostasis than either strain alone. These findings underscore the potential of P. hunanensis RT-12 and S. caprae DS-2 as a bioinoculant consortium for sustainable mitigation of salt stress in cotton cultivation.