Biodegradability and biodegradation pathway of di-(2-ethylhexyl) phthalate by Burkholderia pyrrocinia B1213

• Published in: Chemosphere (Oxford) 2019-06, Vol.225, p.443-450
• Main Authors: Li, Jinlong, Zhang, Jingfan, Yadav, Madhav P., Li, Xiuting
• Format: Article
• Language: English
• Subjects: Biodegradation; Burkholderia pyrrocinia sp; DEHP; Kinetics; Pathway
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2019.02.194

This study was conducted to investigate the biodegradation of di-(2-ethylhexyl) phthalate (DEHP) by Burkholderia pyrrocinia B1213. The results showed that DEHP at concentration of 500 mg/L in a mineral salt medium containing 1.0% yeast extract can be almost completely degraded (98.05%) by strain B1213. The optimal condition for DEHP degradation was pH 7.0, temperature 30 °C. Moreover, B1213 shows better degradation effect on long-chain PAEs, such as DEHP, which provides a great potential for its use in bioremediation of soils contaminated with PAEs. The kinetic studies showed that DEHP depletion curves fit well to the modified Gompertz model. The mono(2-ethylhexyl) phthalate (MEHP), mono-dibutyl phthalate (MBP), phthalic acid (PA) and 4-oxo-hexanoic acid were identified as the metabolites of DEHP by HPLC-ESI-QTOFMS. The detection of MBP and 4-oxo-hexanoic acid as intermediates prompted us to propose a novel and more complete DEHP biodegradation pathway compared to the classic pathway: DEHP is first degraded to MEHP by esterases, which is then converted to MBP through β-oxidation. Then MBP is degraded to PA by esterases, which is then converted to protocatechuate (PCA) under aerobic conditions rapidly. PCA is ultimately cleaved to generate CO2 and H2O via 4-oxo-hexanoic acid. Proposed pathways for DEHP degradation by Burkholderia pyrrocinia B1213. [Display omitted] •B1213 is very efficient to degrade the PAEs with long alkyl chains (such as DEHP).•DEHP depletion curves fit well to the modified Gompertz model.•MBP and 4-oxo-hexanoic acid were the new metabolites of DEHP degradation.•A novel and more complete DEHP biodegradation pathway has been constructed.