Biodegradation of Chlorimuron-ethyl by the Bacterium Klebsiella jilinsis 2N3

Abstract

Enrichment culturing of sludge taken from an industrial wastewater treatment pond led to the identification of a bacterium (Klebsiella jilinsis H. Zhang) that degrades chlorimuron-ethyl with high efficiency. Klebsiella jilinsis strain 2N3 grows with chlorimuron-ethyl as the sole nitrogen source at the optimal temperature range of 30–35°C and pH values between 6.0–7.0. In liquid medium, the degradation activity was further induced by chlorimuron-ethyl. Degradation rates followed the pesticide degradation kinetic equation at concentrations between 20 and 200 mg L⁻¹. Using initial concentrations of 20 and 100 mg L⁻¹, the degradation rates of chlorimuron-ethyl were 83.5 % and 92.5 % in 12 hours, respectively. At an initial concentration higher than 200 mg L⁻¹, the degradation rate decreased slightly as the concentration increased. The 2N3 strain also degraded the sulfonylurea herbicides ethametsulfuron, metsulfuron-methyl, nicosulfuron, rimsulfuron, and tribenuron-methyl. This study provides scientific evidence and support for the application of K. jilinsis in bioremediation to reduce environmental pollution.

Keywords:

• Biodegradation
• chlorimuron-ethyl
• Klebsiella
• 16S rDNA
• phylogenetic analysis

Acknowledgments

This study is supported by grants from the Jilin Provincial Research Foundation for Basic Research (No. 20070568 to H. Zhang), International Cooperation Projects in Changchun City (09GH14 to H. Zhang), the National Science and Technology Pillar Program during the Eleventh Five-Year Plan Period (2006BAD08A08 2009BADB3B05 to H. Pan), Ministry of Agriculture Key Projects of GM. Cultivation of New Varieties (2009ZX08009-062B to H. Pan), and the Jilin Science and Technology Development Plan (20060544 to H. Pan), P. R. China. Authors thank Steven Clough of the USDA-ARS in Urbana, Illinois, USA for assistance in editing, and two anonymous reviewers for comments on the manuscript.

Yu Li, Institute of Mycology, Jilin Agricultural University, Changchun, P.R. China 130118; E-mail: [email protected]

Hao Zhang and Xianghui Zhang contributed equally to this work and should be treated as co-first authors.