Exploring the biosynthetic possibilities of hydroxylated polybrominated diphenyl ethers from bromophenols in Prorocentrum donghaiense: Implications for bioremediation

Bromophenols has been proven to synthesize hydroxylated polybrominated diphenyl ethers (OH-PBDEs), which may pose additional environmental and health risks in the process of bioremediation. In this study, the removal of 2,4-dibromophenol (2,4-DBP) and 2,4,6-tribromophenol (2,4,6-TBP) and the biosynthetic of OH-PBDEs by Prorocentrum donghaiense were explored. The removal efficiencies of 2,4-DBP and 2,4,6-TBP ranged from 32.71% to 76.89% and 31.15%–78.12%, respectively. Low concentrations of 2,4-DBP stimulated algal growth, while high concentrations were inhibitory. Furthermore, exposure to 10.00 mg L−1 2,4-DBP resulted in the detection of 2′-hydroxy-2,3′,4,5′-tetrabromodiphenyl ether (2′–OH–BDE-68) within P. donghaiense. In contrast, increasing concentrations of 2,4,6-TBP considerably inhibited P. donghaiense growth, with 4′-hydroxy-2,3′,4,5′,6-pentabromodiphenyl ether (4′–OH–BDE-121) detected within P. donghaiense under 5.00 mg L−1 2,4,6-TBP. Metabolomic analysis further revealed that the synthesized OH-PBDEs exhibited higher toxicity than their precursors and identified the oxidative coupling as a key biosynthetic mechanism. These findings confirm the capacity of P. donghaiense to remove bromophenols and biosynthesize OH-PBDEs from bromophenols, offering valuable insights into formulating algal bioremediation to mitigate bromophenol contamination.