Biotransformation of quinoline and methylquinolines in anoxic freshwater sediment |
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Authors: | Shiu-Mei Liu W Jack Jones John E Rogers |
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Institution: | (1) University of Georgia, 30602 Athens, Ga, USA;(2) Environmental Research Laboratory, US Environmental Protection Agency, 30605 Athens, Ga, USA;(3) Present address: Institute of Marine Biology, National Taiwan Ocean University, Taiwan, ROC |
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Abstract: | Quinoline (Q) and some isomers of methylquinoline (MQ) were transformed to hydroxylated products in freshwater sediment slurries incubated under methanogenic conditions at 25 °C. Methylquinoline transformation was not affected by a methyl group on the C-3 or C-4 carbon atom of the pyridine ring; 2-MQ, however, was not transformed. All isomers of dimethylquinoline (DMQ) tested (2,4-, 2,6-, 2,7-, and 2,8-DMQ) with a methyl group at the number 2 carbon also persisted in sediments after anaerobic incubation for one year at 25 °C.In most experiments, quinoline initially was transformed to 2-hydroxyquinoline (2-OH-Q), which was further metabolized to unidentified products. A second product, 4-CH3-2-OH-Q, was detected in some experiments. This product accumulated and was not further transformed. 6-, 7-, and 8-Methylquinoline (6-, 7-, 8-MQ) were hydroxylated to form the respective 2-OH-MQ products. These hydroxylated products accumulated and were not further transformed. Hydroxylation of Q and 6-, 7- and 8-MQ at the 2-carbon position was confirmed by GC/FTIR and GC/MS analyses. The transformations of Q and MQs were pH dependent with an optimal pH of 7–8.The results of this study suggest that two pathways may exist for the anaerobic transformation of quinoline; one pathway leads to the formation of a hydroxylated intermediate and the other to a methylated and hydroxylated intermediate. In addition, our results suggest that a methyl substituent on the number 2 carbon inhibits the anaerobic transformation of quinoline derivatives.Abbreviations GC
gas chromatography
- GC/FTIR
gas chromatography/Fourier transform infrared spectrometry
- GC/MS
gas chromatography/mass spectrometry
- HPLC
high performance liquid chromatography
- MQ
methylquinoline
- Q
quinoline |
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Keywords: | biodegradation quinoline methylquinolines anaerobic biotransformation |
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