Departamento de Ingeniería Bioquímica. Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala, Sto. Tomás, CP 11340, México, D.F., Mexico.
Appl Biochem Biotechnol. 2013 Feb;169(4):1418-30. doi: 10.1007/s12010-012-0082-1. Epub 2013 Jan 13.
The main objective of this work was to evaluate the operational stability of a laboratory-scale aerobic biobarrier designed for the treatment of water contaminated by mixtures of three herbicides frequently found in agricultural runoffs, atrazine, simazine and 2,4-dichlorophenoxyacetic acid (2,4-D). The microbial consortium used to degrade the herbicides was composed by six cultivable bacterial strains, identified as members of the genera Variovorax, Sphingopyxis, Hydrocarboniphaga, Methylobacterium, Pseudomonas and Acinetobacter. The effect caused by a seventh member of the microbial consortium, a ciliated protozoa of the genus Colpoda, on the herbicides biodegradation kinetics, was also evaluated. The biodegradation of five combinations of the herbicides 2,4-D, atrazine and simazine was studied in the biobarrier, operated in steady state continuous culture at different volumetric loading rates. In all cases, removal efficiencies determined by chemical oxygen demand (COD) and HPLC were nearly 100 %. These results, joined to the null accumulation of aromatic byproducts of atrazine and simazine catabolism, show that after 495 days of operation, in the presence of the protozoa, the adaptability of the microbial consortium to changing environmental conditions allowed the complete removal of the mixture of herbicides.
本工作的主要目的是评估用于处理受农业径流中常发现的三种除草剂混合物（莠去津、西玛津和 2,4-二氯苯氧乙酸（2,4-D））污染的水的实验室规模好氧生物屏障的运行稳定性。用于降解除草剂的微生物共生物由六种可培养的细菌菌株组成，鉴定为鞘氨醇单胞菌属、鞘氨醇单胞菌属、烃噬氢菌属、甲基杆菌属、假单胞菌属和不动杆菌属的成员。还评估了微生物共生物的第七个成员，即胶毛目纤毛虫属的纤毛原生动物对除草剂生物降解动力学的影响。在生物屏障中研究了 2,4-D、莠去津和西玛津的五种组合的生物降解，生物屏障在不同体积负荷率下以稳定状态连续培养运行。在所有情况下，通过化学需氧量（COD）和高效液相色谱法（HPLC）确定的去除效率均接近 100%。这些结果，加上莠去津和西玛津代谢过程中无芳香副产物的积累，表明在存在原生动物的情况下，微生物共生物对环境条件变化的适应性使得该混合物的除草剂能够被完全去除。
