Bioremediation of Sulfamethazine Contaminated Environments by Bacillus cereus J2

Sulfamethazine (SM2), a prevalent sulfonamide antibiotic, is commonly detected as an environmental pollutant. Microbial degradation serves as an important approach to treating SM2 contamination. In this study, an SM2-degrading strain, identified as Bacillus cereus J2, was isolated from the activated sludge that had been cultured using SM2 as the exclusive carbon source, which demonstrated exceptional degradation capabilities. Under optimized conditions (30 °C, initial OD600 = 0.1, pH = 8), strain J2 completely degraded 50 mg/L SM2 within 36 h. The strain also showed high degradation efficiency for other sulfonamides, such as sulfamethoxazole and sulfadiazine, and could grow normally in a mixed system containing these compounds. The growth kinetics with SM2 as the exclusive carbon source conformed well to the Haldane model (R2 = 0.925), revealing that the strain’s maximum specific growth rate was determined to be 0.066 h−1 (µmax) at an initial SM2 concentration of 51.35 mg/L. Seven intermediate degradation products were identified using TQ-LCMS analysis, suggesting three potential degradation pathways for SM2. These findings suggest that Bacillus cereus J2 holds significant promise for the bioremediation of SM2-contaminated environments.