Hydrolytic Dechlorination of Chlorothalonil by Ochrobactrum sp. CTN-11 Isolated from a Chlorothalonil-Contaminated Soil |
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Authors: | Bin Liang Rong Li Dong Jiang Jiquan Sun Jiguo Qiu Yanfu Zhao Shunpeng Li Jiandong Jiang |
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Institution: | (1) Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, Jiangsu Province, People’s Republic of China; |
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Abstract: | A bacterial strain, designated as CTN-11, capable of degrading chlorothalonil (CTN), was isolated from a chlorothalonil-contaminated
soil in China. Based on the morphological, biochemical characteristics and comparative analysis of the 16S rRNA genes, strain
CTN-11 was identified as Ochrobactrum sp. Strain CTN-11 could degrade 50 mg l−1 CTN to a non-detectable level within 48 h, and efficiently degrade CTN in a relatively broad range of temperatures from 20
to 40°C and initial pH values from 6.0 to 9.0. The new isolate differed from those previously reported CTN co-metabolic degraders
by transforming CTN in the absence of other carbon sources. A glutathione S-transferase (GST) coding gene, which showed 88%
sequence similarity with that from Ochrobactrum anthropi SH35B, was cloned from strain CTN-11. However, the gene was not functionally expressed in the presence of glutathione, indicating
that CTN was not reductively dechlorinated by thiolytic substitution catalyzed by GST in strain CTN-11. The metabolite hydroxyl-trichloroisophthalonitrile
(CTN-OH) produced during CTN anaerobic degradation was identified based on tandem MS/MS, confirming that hydrolytic dechlorination
was involved in the CTN degradation. The removal of CTN by strain CTN-11 in sterile and non-sterile soils was also studied.
In both soil samples, 50 mg kg−1 CTN could be degraded to an undetectable level within 3 days. This study highlights an important potential use of strain
CTN-11 for the cleanup of CTN-contaminated sites and presents a hydrolytic dechlorination reaction of CTN by a pure culture. |
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