Xinjiang has a vast area of saline-alkali soil, accounting for one-third of China’s total saline-alkali land, and soil salinization severely restricts sustainable agricultural development. Lycium ruthenicumMurr., a pioneer plant in Xinjiang’s saline-alkali regions, exhibits strong salt tolerance and medicinal value, but its growth is still limited by nitrogen availability. Azotobacter chroococcum, an aerobic free-living nitrogen-fixing bacterium, can convert atmospheric N₂ into plant-available nitrogen, secrete plant growth regulators, and solubilize insoluble soil nutrients, making it a promising candidate for saline-alkali soil improvement and crop yield enhancement. A salt-tolerant Azotobacter chroococcumstrain A4 isolated from the rhizosphere of Lycium ruthenicumshows excellent salt tolerance and nitrogen-fixing ability, but its unoptimized fermentation conditions limit large-scale application. This study combined AI-assisted design with single-factor experiments and response surface methodology to optimize the fermentation medium for strain A4, aiming to improve its biomass and nitrogenase activity, and provide theoretical and technical support for the development of nitrogen-fixing microbial agents dedicated to saline-alkali lands.

Lycium ruthenicumMurr, Azotobacter chroococcum, Fermentation Condition Optimization, Response Surface Methodology, Cost-benefit Analysis