Zhang Xiao-Lin, Li Yong-Mei, Yuan Zhi-Wen
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
Huan Jing Ke Xue. 2013 Jul;34(7):2889-93.
A strain which was capable of degrading nicosulfuron in the presence of glucose was isolated from nicosulfuron contaminated wetland soil, and it was identified as Klebsiella sp. based on 16S rDNA gene sequencing analysis. The strain could grow using nicosulfuron as the sole nitrogen source. The optimal temperature was 35 degrees C and the initial pH was neutral to weak acid. Hydrolysis experiments indicated that nicosulfuron remained stably under neutral and alkaline conditions, while in acidic conditions, it hydrolyzed quickly. Based on biodegradation experiments, when the concentration of glucose in culture was 5 g x L(-1), the strain could degrade 99.4% of nicosulfuron after incubation for 10 days at 35 degrees C, initial pH = 7; pH of the solution decreased from initial 7.0 to 4.0 in the meantime. When the concentration of glucose in culture solution was decreased to 500 mg x L(-1) and 100 mg x L(-1), with other conditions unchanged, only 11.7% and 6.6% of nicosulfuron were degraded, respectively, and pH of the solution remained at around 7.0. It was proposed that the degradation of nicosulfuron was caused by hydrolysis under acidic conditions at low pH which was resulted from the biodegradation of glucose by the strain. Therefore, the removal of nicosulfuron was actually caused by combined effects of microorganisms and chemical hydrolysis.
从烟嘧磺隆污染的湿地土壤中分离出一株能够在葡萄糖存在的情况下降解烟嘧磺隆的菌株，基于16S rDNA基因测序分析将其鉴定为克雷伯氏菌属。该菌株能够以烟嘧磺隆作为唯一氮源生长。最适温度为35℃，初始pH为中性至弱酸。水解实验表明，烟嘧磺隆在中性和碱性条件下保持稳定，而在酸性条件下迅速水解。基于生物降解实验，当培养物中葡萄糖浓度为5 g·L⁻¹时，该菌株在35℃、初始pH = 7的条件下培养10天后可降解99.4%的烟嘧磺隆；与此同时，溶液的pH从初始的7.0降至4.0。当培养液中葡萄糖浓度降至500 mg·L⁻¹和100 mg·L⁻¹，其他条件不变时，烟嘧磺隆的降解率分别仅为11.7%和6.6%，且溶液的pH保持在7.0左右。研究表明，烟嘧磺隆的降解是由于该菌株对葡萄糖的生物降解导致低pH下酸性条件下水解所致。因此，烟嘧磺隆的去除实际上是微生物和化学水解共同作用的结果。
