Unveiling the Potential of Rhizospheric Bacillus subtilis to Enhance Nitrogen Metabolism, Soil Microbiota, and Nutrient Uptake Under Cadmium Stress in Maize

ABSTRACT Cadmium (Cd) contamination in agricultural soils poses a major threat to soil health and crop productivity. This study aimed to evaluate the potential of Bacillus subtilis (BSS) in alleviating Cd‐induced stress in maize by improving soil nutrients, modulating microbial communities, reducing Cd accumulation, and enhancing plant growth and nutrient uptake. It is hypothesized that rhizospheric B. subtilis will enhance nitrogen metabolism, restore soil nutrients, improve microbes, and reduce Cd uptake in maize. A pot experiment was conducted comprising six treatments, including control, BSS ( B. subtilis ), Cd25 (25 mg kg −1 ), Cd25BSS, Cd50 (50 mg kg −1 ), and Cd50BSS. Soil properties, enzymatic activities, Cd accumulation, microbial diversity, and ionomic profiles in various maize tissues were analyzed. Application of B. subtilis significantly improved soil nutrient availability, particularly nitrogen (N), phosphorus (P), and potassium (K) under Cd stress. B. subtilis reduced Cd accumulation in maize roots by 58.0% and limited translocation to shoots and grains by 66% and 54.2%, respectively. The health risk index declined by 53.7%. B. subtilis enhanced microbial diversity, increasing the abundance of beneficial phyla such as Pseudomonadota , Bacillati , Chloroflexota , and Myxococcota . Plant biomass and enzymatic activities (nitrate reductase, urease, and glutamine synthetase) improved significantly. Ionome analysis showed significant increases in grain N, P, and K contents by 90.3%, 9.4%, and 8.0%, respectively. Additionally, Acidobacteriota , Actinomycetota , and Bacillati were positively correlated with soil nutrients. B. subtilis effectively mitigates Cd toxicity in maize by enhancing soil health, modulating microbial communities, improving nutrient cycling, and reducing Cd bioaccumulation. These findings support its application as a sustainable biotechnological strategy for remediating Cd‐contaminated soils and improving crop productivity.