Novel hydrolytic de-methylthiolation of the s-triazine herbicide prometryn by Leucobacter sp. JW-1
2017
Liu, Junwei | Hua, Rimao | Lv, Pei | Tang, Jun | Wang, Yi | Cao, Haiqun | Wu, Xiangwei | Li, Qing X.
s-Triazine herbicides have been widely used in recent decades and caused serious concern over contamination of groundwater, surface water and soil. A novel bacterial strain JW-1 was isolated from activated sludge and identified as Leucobacter sp. based on comparative morphology, physiological characteristics and comparison of the 16S rDNA gene sequence. JW-1 was capable of using methylthio-s-triazine prometryn as a sole source of carbon and energy in pure culture. Favorable conditions for prometryn degradation were found at pH7.0–9.0 and temperature of 37–42°C. The degradation half-life of prometryn at 50mgL−1 was remarkably as short as 1.1h, and increased to 6.0h when the initial concentration increased to 400mgL−1. The strain JW-1 could degrade 100% of ametryn, 99% of simetryn, 41% of propazine, 43% of atrazine, 28% of simazine, 12% of terbutylhylazine, 10% of prometon and 13% of atraton at 50mgL−1 of each herbicide in 2days. Prometryn was converted to 2-hydroxypropazine and methanthiol via a novel hydrolysis pathway. 2-Hydroxypropazine was then transformed to N-isopropylammelide and the final product cyanuric acid via two sequential deamination reactions. In addition to biodegradation by Leucobacter sp. JW-1, the hydrolytic de-methylthiolation would be valuable in biocatalysis.
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