Biodegradation of Triphenyl Phosphate by Gordonia polyisoprenivorans YC-XJ4: Environmental Adaptability and Bioremediation Potential

Abstract

Triphenyl phosphate (TPHP) is a widely used organophosphate flame retardant (OPFR) with concerning environmental persistence and toxicity. Microbial degradation is a promising removal strategy, but highly efficient degraders outside the Sphingomonadaceae family remain rarely reported. In this study, a highly efficient TPHP-degrading strain, designated YC-XJ4, was isolated from plastic-waste-contaminated soil and identified as Gordonia polyisoprenivorans through genomic analysis. The strain exhibited robust degradation activity over broad ranges of temperature (15–40 °C), pH (6.0–10.0), and salinity (0–2% NaCl), with a maximum average degradation velocity of 9.41 mg/(L·h) at an initial TPHP concentration of 300 mg/L and approximately 30% degradation retained at 500 mg/L. Substrate spectrum analysis showed that YC-XJ4 preferentially degraded aryl-OPFRs (TPHP, tricresyl phosphate, and 2-ethylhexyl diphenyl phosphate), whereas no degradation was detected for chlorinated or alkyl congeners. Whole-genome sequencing revealed the absence of known OPFR phosphotriesterase genes, suggesting that TPHP degradation in strain YC-XJ4 may be mediated by novel enzymes. In simulated bioremediation experiments conducted under natural outdoor conditions, the strain effectively removed TPHP from both soil and seawater. In soil, with a 5% (v/v) inoculum, the TPHP concentration decreased from 100 mg/kg to 4.66 mg/kg within 10 h (95.34% removal), while in seawater, 86.41% removal was achieved within 20 h at the same inoculum size. Collectively, G. polyisoprenivorans YC-XJ4 represents a promising non-Sphingomonadaceae degrader with strong environmental adaptability and practical bioremediation potential, providing a valuable candidate for both application and the discovery of novel degrading enzymes.