What is 3-phenoxybenzoate(3-PBA)?

3-phenoxybenzoate (Fig 1) is the main metabolite in the degradation of insecticide pyrethroids.3-phenoxybenzoate (3-PBA) is a diaryl ether compound.Fig1

Fig.1. The structure of 3-phenoxybenzoate

Fig.2. Degradation pathway of 3-phenoxybenzoate by gene cluster pbaA1A2B and pbaC

Fig.3. The figure shows the growth situation of Sphingobium wenxiniae

JZ-1^T and E.coli DH5αin different concentration of 3- phenoxybenzoateby testing OD value at the 24th hour. In every group, the left column belongs to our engineering bacteria and the right one belongs toSphingobium wenxiniae JZ-1^T.

Result

We found that our engineering bacteriagrow faster than Sphingobium wenxiniae JZ-1^T and can tolerate higher concentration of 3-phenoxybenzoate than Sphingobium wenxiniae JZ-1^T.

HPLC(High Performance Liquid Chromatography) test

We set a serious of solutions with different concentration(200umol/L, 500umol/L, 1000umol/L, 1500umol/L, 2500umol/Lto test the degradation of 3- phenoxybenzoate usingour engineering bacteria.

Fig.4. Show the degradation of 3-phenoxybenzoateusingour engineering bacteria.

At present, 20% of 3-phenoxybenzoate in solution can be degraded by our engineering bacteriain 40 hours and most of degradation occurs in 24 hours.We can also found that the higher the concentration of 3-phenoxybenzoate is， the more 3-phenoxybenzoate will be degraded. Our engineering bacteria can work in solution with 2500μmol/L of 3-phenoxybenzoate which can not be tolerated by Sphingobium wenxiniae JZ-1^T. Although our engineering bacteria can not degrade 3-phenoxybenzoatefleetly now, its tolerance can satisfy the demand of treating 3-phenoxybenzoate-enriched water. Considering Sphingobium wenxiniae JZ-1^T can lose its ability for degrading 3-phenoxybenzoate easily, our engineering bacteriahas the advantage in this respect.After several generations of propagation, we couldn’t get gene pbaA1A2B from Sphingobium wenxiniae JZ-1^T using PCR. In addition,through testing the ability of degrading 3-phenoxybenzoate of Sphingobium wenxiniae JZ-1^T using MSM which contains different concentration of 3-phenoxybenzoate,we found JZ-1 could not live in the MSM medium using 3-PBA as sole carbon source.