Behavior and mechanism of Sr2+ adsorption by radiation-resistant Bacillus cereus BC-11

Radioactive strontium is a priority contaminant in nuclear wastewater because of its high environmental mobility and long-term health risks. In this study, a Bacillus cereus strain, BC-11, was isolated from soil surrounding an irradiation facility. BC-11 maintained growth under Sr 2+ stress and exhibited optimal adsorption at pH 7.0, 30℃, 150 rpm, and a biomass dosage of 100 mg. The Langmuir model best described the adsorption isotherm, with a theoretical maximum adsorption capacity of 26.1 mg/g, suggesting monolayer adsorption on finite and specific active sites. Sr 2+ adsorption followed the pseudo-second-order model, indicating that chemisorption dominated the uptake process. SEM-EDS confirmed progressive Sr accumulation on the bacterial surface, while FTIR analysis showed that carboxyl, phosphate, hydroxyl, amino, and amide groups participated in Sr 2+ fixation through surface complexation and ion exchange. Proteomic analysis suggested that BC-11 regulated cell wall remodeling, secretion systems, ABC transporters, and energy metabolism to control strontium transport. This study identifies a radiation-resistant Bacillus cereus strain with efficient Sr 2+ adsorption, highlighting its potential for remediating radioactive strontium-contaminated wastewater.