Harnessing Bacillus thuringiensis and Bacillus cereus for Effective Biodegradation of Endocrine Disruptor 4-Nonylphenol

4-Nonylphenol (4-NP), an important fine chemical precursor, can cause endocrine disruption, resist natural degradation, and bioconcentrate. Biodegradation is an effective and environmentally sustainable approach to its remediation. This study employed a mixture comprising equal proportions of six non-pathogenic Bacillus strains to screen and identify strains capable of degrading 4-NP, and degradation rate was measured using an ELISA kit, and metabolomic analyses and whole-genome sequencing were used to investigate the response of Bacillus to 4-NP and elucidate pathways involved in 4-NP degradation. The results revealed DY and LY strains isolated at 500 μg/L 4-NP. The DY strain was identified as Bacillus thuringiensis, and the LY strain was identified as Bacillus cereus via physiological, biochemical and PCR analyses. The degradation efficiency of a DY and LY strain mixture was 79.45% after 7 days. At 1000 μg/L 4-NP, only the LY strain was successfully isolated. Whole-genome sequencing indicated that the LY strain (accession number: CRA021210) shares the highest homology with B. cereus strain FORC-047. Notably, it showed a degradation rate of 86.34% after 7 days. Metabolomics analysis indicates that 4-NP affects the degradation pathways of aromatic compounds and benzoic acid in B. cereus. Combined with genome data, it is hypothesized that the 4-NP degradation pathway involves its conversion to p-hydroxybenzoic acid, catalyzed by monooxygenases, dioxygenases and oxidases. Subsequently, p-hydroxybenzoic acid degrades via one of two potential pathways: it produces phenol through decarboxylase or is oxidized to benzoic acid by monooxygenase. In summary, the DY and LY strains are capable of degrading 4-NP. Furthermore, we postulate potential 4-NP degradation pathways, providing insights for the remediation of 4-NP in aquatic environments.