Biodegradation pathway and mechanism of tri (2-chloropropyl) phosphate by Providencia rettgeri

Tri (2-chloropropyl) phosphate (TCPP) was an emerging contaminant of global concern because of its frequent occurrence, potential toxic effects, and persistence in the environment. Microbial degradation might be an efficient and safe removal method, but limited information was available. In this study, Providencia rettgeri was isolated from contaminated sediment and showed it could use TCPP as unique phosphorus source to promote growth, and decompose 34.7% of TCPP (1 mg/L) within 5 days. The microbial inoculation and the initial concentration of TCPP could affect the biodegradation efficient. Further study results indicated that TCPP decomposition by Providencia rettgeri was mainly via phosphoester bond hydrolysis, evidenced by the production of bis (2-chloropropyl) phosphate (C₆H₁₃Cl₂PO₄) and mono-chloropropyl phosphate (C₃H₈ClPO₄). Both intracellular and extracellular enzymes could degrade TCPP, but intracellular degradation was dominant in the later reaction stage, and the presence of Cu²⁺ ions had a promoting effect. These findings developed novel insights into the potential mechanism of TCPP microbial degradation.