Degradation of aromatic compounds and degradative pathway of 4-nitrocatechol by Ochrobactrum sp. B2

Abstract

The potential capacity of a soil methyl parathion-degrading bacterium strain, Ochrobactrum sp. B2, for degrading various aromatic compounds were investigated. The results showed B2 was capable of degrading diverse aromatic compounds, but amino-substituted benzene compounds, at a concentration up to 100 mg L⁻¹ in 4 days. B2 could use 4-nitrocatechol (4-NC) as a sole carbon and energy source with release of nitrite ion. The pathway for 4-NC degradation via 1,2,4-benzenetriol (BT) and hydroquinone (HQ) formation in B2 was proposed based on the identification and quantification of intermediates by gas chromatography-mass spectrometry (GC-MS), and high performance liquid chromatography (HPLC). Degradation studies carried out on a plasmid-cured derivative showed that the genes for 4-NC degradative pathway was plasmid-borne in B2, suggesting that B2 degrades both p-nitrophenol and 4-NC by enzymes encoded by genes on the same plasmid.

Keywords:

• Biodegradation
• degradative pathway
• 4-nitrocatechol
• Ochrobactrum sp. B2
• plasmid

Acknowledgments

This research is financed by grants from the Innovation Program (No.KSCX2-SW-128) and the Presidential Fund of the Chinese Academy of Sciences. We would thank reviewers for valuable comments, and Ms. Xiaowei Qin for technical assistance in HPLC and GC-MS.

Current address for Qiuzan Zhong is Wenzhou Institute of Calibration and Testing for Quality and Technical Supervision. Received March 26, 2007.

Notes

^aThe metabolites were identified after comparison with standard compounds.