Complete biodegradation of di-n-butyl phthalate (DBP) by a novel Pseudomonas sp. YJB6

Nai-Xian FENG, Yu-Xi FENG, Qi-Feng LIANG, Xin CHEN, Lei XIANG, Hai-Ming ZHAO, Bai-Lin LIU, Gang CAO, Yan-Wen LI, Hui LI, Quan-Ying CAI, Ce-Hui MO, Ming Hung WONG

Research output: Contribution to journalArticlespeer-review

Abstract

Phthalate acid esters (PAEs) are environmentally ubiquitous and have aroused a worldwide concern due to their threats to environment and human health. Di-n-butyl phthalate (DBP) is one of the most frequently observed PAEs in the environment. In this study, a novel bacterium identified as Pseudomonas sp. YJB6 that isolated from PAEs-contaminated soil was determined to have strong DBP-degrading activity. A complete degradation of DBP in 200 mg/L was achieved within 3 days when YJB6 was cultivated at 31.4 °C with an initial inoculation size of 0.6 (OD600) in basic mineral salts liquid medium (MSM), pH 7.6. The degradation curves of DBP (50–2000 mg/L) fitted well the first-order kinetics model, with a half-life (t1/2) ranging from 0.86 to 1.88 d. The main degradation intermediates were identified as butyl-ethyl phthalate (BEP), mono-butyl phthalate (MBP), phthalic acid (PA) and benzoic acid (BA), indicating a new complex and complete biodegradation pathway presented by YJB6. DBP might be metabolized through de-esterification, β-oxidation, and hydrolysis, followed by entering the Krebs cycle of YJB6 as a final step. Strain YJB6 was successfully immobilized with sodium alginate (SA), polyvinyl alcohol (PVA), and SA-PVA. The immobilization significantly improved the stability and adaptability of the cells thus resulting in high volumetric DBP-degrading rates compared to that of the freely suspended cells. In addition, these immobilized cells can be reused for many cycles with well conserved in DBP-degrading activity. The ideal DBP degrading ability of the free and immobilized YJB6 cells suggests that strain YJB6, especially the SA-PVA+ YJB6 promises great potential to remove hazardous PAEs. Copyright © 2020 Elsevier B.V. All rights reserved.
Original languageEnglish
Article number143208
JournalScience of the Total Environment
Early online date27 Oct 2020
DOIs
Publication statusE-pub ahead of print - 27 Oct 2020

Citation

Feng, N.-X., Feng, Y.-X., Liang, Q.-F., Chen, X., Xiang, L., Zhao, H.-M., . . . Wong, M. H. (2020). Complete biodegradation of di-n-butyl phthalate (DBP) by a novel Pseudomonas sp. YJB6. Science of the Total Environment. Advance online publication. doi: 10.1016/j.scitotenv.2020.143208

Keywords

  • Phthalate acid esters (PAEs)
  • Degradation kinetics
  • Metabolic pathway
  • Immobilization
  • Bioremediation

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