Bioremediation of triphenyl phosphate by Brevibacillus brevis: Degradation characteristics and role of cytochrome P450 monooxygenase

Triphenyl phosphate (TPHP) has been detected with increasing frequency in environmental samples, which has aroused great attention regarding its potential adverse effects. In this study, biodegradation of TPHP by Brevibacillus brevis was investigated. The results revealed that the highest degradation efficiency of 3μmol/L TPHP by B. brevis reached 92.1% at pH7 and 30°C. The major metabolites of TPHP, diphenyl phosphate and phenyl phosphate were detected within 5days of incubation with the maximum concentrations at 308.2 and 11.8nmol/L, respectively. The activities of superoxide dismutase and catalase along with malondialdehyde content also increased significantly, indicating that TPHP caused a severe oxidative stress on B. brevis. Meanwhile, the addition of cytochrome P450 (CYP) inhibitor piperonyl butoxide markedly decreased the degradation of TPHP by B. brevis. Further transcription studies using quantitative real-time RT-PCR confirmed that the expression of CYP gene in B. brevis were significantly down-regulated. These findings demonstrated the important role of CYP in the degradation of TPHP. To our best knowledge, this is the first report about the biodegradation of TPHP by B. brevis. Overall, this study provides new insights into the potential mechanisms of TPHP biodegradation by microorganisms.