In vitro biotransformation of PBDEs by root crude enzyme extracts: Potential role of nitrate reductase (NaR) and glutathione S-transferase (GST) in their debromination

• Published in: Chemosphere (Oxford) Vol. 90; no. 6; pp. 1885 - 1892
• Main Authors: Huang, Honglin, Zhang, Shuzhen, Wang, Sen, Lv, Jitao
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.02.2013; Elsevier
• Subjects: Biodegradation of pollutants; Biodegradation, Environmental; Biological and medical sciences; Biotechnology; Biotransformation; bromination; catalase; corn; cytochrome P-450; Environment and pollution; enzyme activity; Fundamental and applied biological sciences. Psychology; glutathione transferase; Glutathione Transferase - metabolism; Halogenated Diphenyl Ethers - chemistry; Halogenated Diphenyl Ethers - metabolism; Halogenation; In vitro; Industrial applications and implications. Economical aspects; Lolium; nitrate reductase; Nitrate Reductase - metabolism; PBDEs; peroxidase; Plant Extracts - chemistry; Plants - metabolism; pumpkins; Root crude enzyme extracts; Soil Pollutants - chemistry; Soil Pollutants - metabolism; In vitro; PBDEs; Biotransformation; Root crude enzyme extracts; Dehalogenation; Extract; Persistent organic pollutant; Glutathione transferase; Polybromo diphenyl ether; Bromine Organic compounds; Below ground plant part; Debromination; Biodegradation; Ether; Root; Enzyme; Pollutant behavior; Transferases; Flame retardant; Low volatile compound; Nitrate reductase; Plant origin; Oxidoreductases; Degradation product; Enzymatic reaction
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2012.10.013

► PBDEs could be debrominated and hydroxylated by the root crude enzyme extracts. ► Debromination was the main degradation pathway. ► In vitro and in vivo exposure to PBDEs produced the similar enzyme responses. ► NaR and GST were the key enzymes in the plant degradation of PBDEs. In order to investigate the enzyme transformation of PBDEs and to track the key enzymes involved in PBDE degradation in plants, in vivo exposure of plants of ryegrass, pumpkin and maize and in vitro exposure of their root crude enzyme extracts to PBDEs were conducted. Degradation of PBDEs in the root crude enzyme solutions fit well with the first order kinetics (R2=0.52–0.97, P<0.05), and higher PBDEs degraded faster than the lower ones. PBDEs could be transformed to lower brominated PBDEs and hydroxylated-PBDEs by the root crude enzyme extracts with debromination as the main pathway which contributed over 90% of PBDE depletion. In vitro and in vivo exposure to PBDEs produced similar responses in root enzyme activities of which the nitroreductase (NaR) and glutathione-transferase (GST) activities decreased significantly, while the peroxidase, catalase and cytochrome P-450 activities had no significant changes. Furthermore, higher enzyme concentrations of NaR and GST led to higher PBDE debromination rates, and the time-dependent activities of NaR and GST in the root crude enzyme extracts were similar to the trends of PBDE depletion. All these results suggest that NaR and GST were the key enzymes responsible for PBDE degradation. This conclusion was further confirmed by the in vitro debromination of PBDEs with the commercial pure NaR and GST.