Deciphering cadmium effects on biodegradation of triphenyl phosphate in sediments: Insights from molecular biology and computational chemistry.

The widespread co-existence of triphenyl phosphate (TPhP) and heavy metals in sediments raises significant concerns. However, uncertainty still exists regarding the degradation characteristics of TPhP in the presence of cadmium (Cd). Therefore, this research was conducted to elucidate the impacts of Cd on TPhP degradation in sediments. Results showed that the biodegradation efficiency of TPhP in sediments exceeded 90 %. The identified degradation products of TPhP indicated that the degradation pathway primarily involved oxidative cleavage, hydroxylation, and methylation, which was further supported by condensed dual descriptors (CDD). However, the presence of Cd significantly inhibited TPhP degradation, with greater inhibition at higher concentrations of both TPhP and Cd. Transcriptomic analysis revealed that xenobiotic metabolism was significantly suppressed. Furthermore, pathways associated with cell motility, membrane transport, and energy metabolism were impaired. These disruptions likely contributed to the decreased degradation efficiency and prolonged half-life of TPhP. Interestingly, biomarkers in Firmicutes were enriched in the high-concentration TPhP + Cd treatment and strongly correlated with degradation-related gene expression, suggesting their significance in TPhP degradation under heavy metal stress. Overall, this research provides insights into the inhibitory effects of Cd on TPhP degradation and offers theoretical support for the bioremediation of TPhP-contaminated sediments with heavy metals.