Key Laboratory of Integrated Pest Management on Crops in Southwest, Ministry of Agriculture, Institute of Plant Protection, Sichuan Academy of Agricultural Science, Chengdu, 610066, People's Republic of China.
Biodegradation. 2018 Jun;29(3):271-283. doi: 10.1007/s10532-018-9828-y. Epub 2018 Apr 10.
A bacterial strain NSA02, isolated from contaminated soil and identified as Pseudomonas nitroreducens based on partial 16S rDNA gene sequence analysis and BIOLOG microbiology analysis, was used to study biodegradation of nicosulfuron in the culture medium. The optimal degradation conditions were determined to be 30 °C and pH 7.0. Batch tests were performed for seven different initial substrate concentrations to observe substrate degradation and associated cell growth. The biodegradation kinetics was found to follow a first-order model with regression values greater than 0.98. Specific degradation rate and specific growth rate of bacterial cells were observed to follow substrate inhibition kinetics, and the maximum values of both rates were observed at 100 mg L of nicosulfuron concentration. Kinetic parameters of three substrate inhibition models (Haldane, Aiba-Edwards and Teissier-Edwards) were fitted to the relationship between those rates and substrate concentrations. With the date obtained, Haldane and Teissier-Edwards models provide better representation when compared to Aiba-Edwards model. Inoculating nicosulfuron-treated soil samples with strain NSA02 resulted in a 5-6 times higher rate of nicosulfuron removal than that in non-inoculated soil. Five metabolites of nicosulfuron degradation were detected and identified by liquid chromatography mass spectrometry, and three possible biotransformation pathways were proposed. These results highlight the potential of the isolated bacterium to be used in the bioremediation of nicosulfuron-contaminated soils.
从污染土壤中分离到的一株细菌 NSA02，根据部分 16S rDNA 基因序列分析和 BIOLOG 微生物分析鉴定为假单胞菌属硝基还原菌，用于研究培养基中烟嘧磺隆的生物降解。确定最佳降解条件为 30°C 和 pH 7.0。进行了七种不同初始底物浓度的分批试验，以观察底物降解和相关细胞生长。生物降解动力学符合一级模型，回归值大于 0.98。观察到细菌细胞的比降解速率和比生长速率遵循底物抑制动力学，在 100mg/L 烟嘧磺隆浓度下观察到这两个速率的最大值。拟合了三种底物抑制模型（Haldane、Aiba-Edwards 和 Teissier-Edwards）的动力学参数与这些速率和底物浓度之间的关系。与 Aiba-Edwards 模型相比，Haldane 和 Teissier-Edwards 模型提供了更好的拟合效果。用 NSA02 菌株接种处理过的烟嘧磺隆土壤样品，比未接种的土壤样品的烟嘧磺隆去除率高 5-6 倍。通过液相色谱-质谱联用检测和鉴定了烟嘧磺隆降解的 5 种代谢物，并提出了 3 种可能的生物转化途径。这些结果突出了分离菌在烟嘧磺隆污染土壤的生物修复中的应用潜力。
