Degradation Of Di (2-ethylhexyl) Phthalate By A Novel Gordonia Alkanivorans Strain YC-RL2

One bacterial strain YC-RL2, isolated from petroleum contaminated soil, could utilize environmental hormone di(2-ethylhexyl) phthalate(DEHP) as sole carbon source for growth. Strain YC-RL2 was identified as Gordonia alkanivorans by 16 S rRNA gene analysis and Biolog tests.The effects of environmental factors which might affect the degrading process were optimized as 30 °C and pH 8.0. Strain YC-RL2 showed superior halotolerance and could tolerate up to 0-5% NaCl in trace element medium supplemented with DEHP, although the DEHP degradation rates slowed as NaCl concentration increased. It also showed an outstanding performance in a wide range of pH(6.0-11.0). Meanwhile, strain YC-RL2 was able to withstand high concentrations of DEHP(from 100 to 800 mg/L) and the degradation rates were all above 94 %. The DEHP metabolites were detected by HPLC-MS and the degradation pathway was deduced tentatively. DEHP was transformed into phthalic acid(PA) via mono(2-ethylhexyl) phthalate(MEHP) and PA was further utilized for growth via benzoic acid(BA). The enzyme expected to hydrolyze MEHP to PA was identified from strain YC-RL2. Further investigation found that the enzyme could catalyze the transformation of a wide range of monoalkyl phthalates(MAPs) to PA. The application potential of strain YC-RL2 in remediating contaminated sites was investigated using artificially contaminated soil and it was found that 76% of DEHP was degraded in sterilized soil treatment while only 44% was degraded in the non-sterilized soil treatment. This study is the first report about a halotolerantGordonia alkanivorans which could degrade several kinds of PAEs and indicates its application potential for bioremediation of PAEs polluted sites.