Oxidation of polycyclic aromatic hydrocarbons by the bacterial laccase CueO from E. coli.
Laccases produced by white rot fungi are capable of rapidly oxidizing benzo[a]pyrene. We hypothesize that the polycyclic aromatic hydrocarbon (PAH)-degrading bacteria producing laccase can enhance the degree of benzo[a]pyrene mineralization. However, fungal laccases are glycoproteins which cannot be glycosylated in bacteria, and there is no evidence to show that bacterial laccases can oxidize benzo[a]pyrene. In this study, the in vitro oxidation of PAHs by crude preparations of the bacterial laccase, CueO, from Escherichia coli was investigated. The results revealed that the crude CueO catalyzed the oxidation of anthracene and benzo[a]pyrene in the same way as the fungal laccase from Trametes versicolor, but showed specific characteristics such as thermostability and copper dependence. In the presence of 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid), high amounts of anthracene and benzo[a]pyrene, 80% and 97%, respectively, were transformed under optimal conditions of 60°C, pH 5, and 5 mmol l(-1) CuCl(2) after a 24-h incubation period. Other PAHs including fluorene, acenaphthylene, phenanthrene, and benzo[a]anthracene were also oxidized by the crude CueO. These findings indicated the potential application of prokaryotic laccases in enhancing the mineralization of benzo[a]pyrene by PAH-degrading bacteria.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, People's Republic of China.
Jun
J
Zeng
Xiangui
X
Lin
Jing
J
Zhang
Xuanzhen
X
Li
Ming Hung
MH
Wong
D000873:Anthracenes / Q000378:metabolism; D001564:Benzo(a)pyrene; D003067:Coenzymes / Q000378:metabolism; D045424:Complex Mixtures / Q000302:isolation & purification / Q000378:metabolism; D003300:Copper / Q000378:metabolism; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D042845:Laccase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism*; D013696:Temperature; D055454:Trametes / Q000378:metabolism
D000873:Anthracenes; D003067:Coenzymes; D045424:Complex Mixtures; D029968:Escherichia coli Proteins; D011084:Polycyclic Aromatic Hydrocarbons; D001564:Benzo(a)pyrene; D003300:Copper; D010088:Oxidoreductases; C499679:cueO protein, E coli; D042845:Laccase; C034020:anthracene