The Efficient PAE Degradation by Glutamicibacter sp. FR1 and Its Molecular Mechanism

Phthalic acid esters (PAEs) are important plasticizers that have led to the heavy pollution of farmland, which has aroused significant and widespread concern for soil health and food safety. Microbial degradation has been recognized as an efficient pathway for removing PAEs from the environment. In this study, the PAE-degrading strain FR1 was isolated from sewage and determined to belong to Glutamicibacter. This strain degraded PAEs efficiently under a wide range of conditions—10–50 °C, pH of 6.0–11.0, and 0–8% salinity—demonstrating its great potential in PAE bioremediation. Genome sequencing provided complete genomic information, showing that the strain comprises one chromosome (3,404,214 bp) and three plasmids (112,089 bp, 80,486 bp, and 40,002 bp). The chromosome harbors 3238 protein genes, of which the PAE hydrolase genes dphGB1 and mphGB2 have been cloned. The hydrolase DphGB1 from hydrolase family I contained the catalytic triad Ser75-Asp194-His221. After heterogeneous expression and purification, the recombinant protein DphGB1, of about 30 kDa, was obtained. This hydrolase showed strong hydrolytic ability toward DEHP. The protein MphGB2 could also hydrolyze MBP. The molecular docking revealed interaction between DphGB1 and DBP. The main hydrolases of strain FR1-degrading PAEs were functionally identified. These results will promote the elucidation of the catalytic mechanisms of PAE hydrolases and the application of strain FR1 in farmland soil remediation.