Biodegradation of hexachlorobenzene by a constructed microbial consortium
- 523 Downloads
A consortium comprised of an engineered Escherichia coli DH5α and a natural pentachlorophenol (PCP) degrader, Sphingobium chlorophenolicum ATCC 39723, was assembled for degradation of hexachlorobenzene (HCB), a persistent organic pollutant. The engineered E. coli strain, harbouring a gene cassette (camA + camB + camC) that encodes the F87W/Y96F/L244A/V247L mutant of cytochrome P-450cam (CYP101), oxidised HCB to PCP. The resulting PCP was then further completely degraded by ATCC 39723. The results showed that almost 40 % of 4 μM HCB was degraded by the consortium at a rate of 0.033 nmol/mg (dry weight)/h over 24 h, accompanied by transient accumulation and immediate consumption of the intermediate PCP, detected by gas chromatography. In contrast, in the consortium comprised of Pseudomonas putida PaW340 harbouring camA + camB + camC and ATCC 39723, PCP accumulated in PaW340 cells but could not be further degraded, which may be due to a permeability barrier of Pseudomonas PaW340 for PCP transportation. The strategy of bacterial co-culture may provide an alternative approach for the bioremediation of HCB contamination.
KeywordsBiotransformation Cytochrome P-450cam Hexachlorobenzene Pentachlorophenol Sphingobiumchlorophenolicum ATCC 39723
This work was supported by the Natural Science Foundation of Hubei Province of China (2008CDB067) and the National Natural Science Foundation of China (NSFC, Project No. 31270112). We thank Luet-Lok Wong for the gift of plasmid pCWSGB-camC and Luying Xun for providing Sphingobium chlorophenolicum ATCC 39723.
- Arfmann H, Timmis KN, Wittich R (1997) Mineralization of 4-chlorodibenzofuran by a consortium consisting of Sphingomonas sp. strain RW1 and Burkholderia sp. strain JWS. Appl Environ Microbiol 63:3458–3462Google Scholar
- Chen X, Christopher A, Jones JP, Bell SG, Guo Q, Xu F, Rao Z, Wong LL (2002) Crystal structure of the F87W/Y96F/V247L mutant of cytochrome P-450cam with 1,3,5-trichlorobenzene bound and further protein engineering for the oxidation of pentachlorobenzene and hexachlorobenzene. J Biol Chem 277:37519–37526CrossRefGoogle Scholar
- Fathepure BZ, Tiedje JM, Boyd SA (1988) Reductive dechlorination of hexachlorobenzene to tri- and dichlorobenzenes in anaerobic sewage sludge. Appl Environ Microbiol 54:327–330Google Scholar
- Jacoff FS, Scarberry R, Rosa D (1986) Source assessment of hexachlorobenzene from the organic chemical manufacturing industry. IARC Sci Publ 77:31–37Google Scholar
- Jeenes DJ, Williams PA (1982) Excision and integration of degradative pathway genes from TOL plasmid pWW0. J Bacteriol 150:188–194Google Scholar
- Saber DL, Crawford RL (1985) Isolation and characterization of Flavobacterium strains that degrade pentachlorophenol. Appl Environ Microbiol 50:1512–1518Google Scholar
- Sambrook J, Russell DW (2001) Molecular cloning: a laboratory manual, 3rd edn. Cold Spring Harbor Laboratory Press, New YorkGoogle Scholar
- Williams PA, Murray K (1974) Metabolism of benzoate and the methylbenzoates by Pseudomonas putida (arvilla) mt-2: evidence for the existence of a TOL plasmid. J Bacteriol 120:416–423Google Scholar
- Yeh DH, Pavlostathis SG (2001) Development of hexachlorobenzene-dechlorinating mixed cultures using polysorbate surfactants as a carbon source. Water Sci Technol 43:43–50Google Scholar