Xu Jun, Li Xuesheng, Xu Yanjun, Qiu Lihong, Pan Canping
Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China.
Chemosphere. 2009 Feb;74(5):682-7. doi: 10.1016/j.chemosphere.2008.09.078. Epub 2008 Nov 11.
Three bacterial strains capable of transforming pyrazosulfuron-ethyl, designated as D61, D66, and D713, were isolated from pyrazosulfuron-ethyl contaminated soils. According to the sequence analysis of the partial 16S rRNA gene, it is found that the strains D61 and D66 belong to Pseudomonas sp., and the strain D713 belongs to Bacillus sp. The effects of pyrazosulfuron-ethyl concentration, pH and temperature on biodegradation were examined. At a concentration of 10.0mgL(-1), pyrazosulfuron-ethyl was completely degraded by Pseudomonas sp. D61 after 2d and by Pseudomonas sp. D66 after 5d. At a concentration of 90.0mgL(-1), pyrazosulfuron-ethyl can be completely degraded by Pseudomonas sp. D66 and D61 after 12d. More than 85.9% degradation rate was observed with Bacillus sp. D713 after 12d. The growth of these three strains was inhibited at low pH buffers. The abiotic degradation occurs much faster at low pH than at neutral and basic pH conditions. The degradation rate of pyrazosulfuron-ethyl at 28 degrees C was faster than those at 20 degrees C and 37 degrees C by these strains, except the highest degradation rate of Bacillus sp. D713 was obtained at 37 degrees C. The pyrazosulfuron-ethyl biodegradation products were identified by liquid chromatography-mass spectroscopy with positive/negative modes and tandem MS-MS techniques. The main degradation product was detected and identified as 5-(N-(4,6-dimethoxypyrimidin-2-ylcarbamoyl)sulfamoyl)-1-methyl-1H-pyrazole-4-carboxylic acid based on mass spectral data and fragmentation patterns.
从吡嘧磺隆污染土壤中分离出三株能够转化吡嘧磺隆的细菌菌株，分别命名为D61、D66和D713。通过对部分16S rRNA基因的序列分析发现，菌株D61和D66属于假单胞菌属，菌株D713属于芽孢杆菌属。考察了吡嘧磺隆浓度、pH值和温度对生物降解的影响。在浓度为10.0mgL(-1)时，假单胞菌属D61在2d后可将吡嘧磺隆完全降解，假单胞菌属D66在5d后可将其完全降解。在浓度为90.0mgL(-1)时，假单胞菌属D66和D61在12d后可将吡嘧磺隆完全降解。芽孢杆菌属D713在12d后的降解率超过85.9%。这三株菌在低pH缓冲液中生长受到抑制。非生物降解在低pH条件下比在中性和碱性pH条件下发生得更快。除芽孢杆菌属D713在37℃时降解率最高外，这三株菌在28℃时对吡嘧磺隆的降解速率均快于20℃和37℃时。采用液相色谱-质谱正/负模式和串联质谱技术对吡嘧磺隆的生物降解产物进行了鉴定。根据质谱数据和碎片模式，检测并鉴定出主要降解产物为5-(N-(4,6-二甲氧基嘧啶-2-基氨基甲酰基)氨磺酰基)-1-甲基-1H-吡唑-4-羧酸。
