Institute of Natural Resources and Agrobiology of Seville, Spanish National Research Council (IRNAS-CSIC), Department of Agrochemistry, Environmental Microbiology and Soil Conservation, Seville, Spain; Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, Seville, Spain.
Institute of Natural Resources and Agrobiology of Seville, Spanish National Research Council (IRNAS-CSIC), Department of Agrochemistry, Environmental Microbiology and Soil Conservation, Seville, Spain.
Sci Total Environ. 2022 Sep 20;840:156695. doi: 10.1016/j.scitotenv.2022.156695. Epub 2022 Jun 13.
Trifluralin (TFL) is a highly persistent with a strong adsorption capacity on soil particles herbicide. This study was to isolate microbial consortia and bacterial strains from a soil with a historical application of pesticides to evaluate their potential to degrade TFL in soil. Different bioremediation techniques were considered for increasing the effectiveness of TFL degradation in soil. These techniques consisted of: i) biostimulation, using a nutrients solution (NS); ii) bioaugmentation, using a natural microbial consortium (NMC), seven individual bacterial strains isolated from NMC, and an artificial bacterial consortium formed by the seven TFL-degrading bacterial strains (ABC); iii) bioavailability enhancement, using a biodegradable compound, a randomly methylated cyclodextrin, RAMEB. Biostimulation using NS leads up to 34 % of soil TFL biodegraded after 100 d. When the contaminated soil was inoculated with NMC or ABC consortia, TFL loss increased up to 62 % and 74 %, respectively, with DT values (required time for the pollutant concentration to decline to half of its initial value) of 5.9 and 11 d. In the case of soil inoculation with the isolated individual bacterial strains, the extent of TFL biodegradation ranged widely from 2.3 % to 55 %. The most efficient bacterial strain was Arthrobacter aurescens CTFL7 which had not been previously described in the literature as a TFL-degrading bacterium. Bioaugmentation with CTFL7 bacterium was also tested in the presence of RAMEB, provoking a drastic increase in herbicide biodegradation up to 88 %, achieving a DT of only 19 d. Cyclodextrins had never been tested before for enhancement of TFL biodegradation. An ecotoxicity assay was performed to confirm that the proposed bioremediation techniques were also capable to reduce toxicity. A Microtox® test showed that after application A. aurescens CTF7 and A. aurescens CTF7 + RAMEB, the TFL-contaminated soil, which initially presented acute toxicity, became non-toxic at the end of the biodegradation experiments.
氟乐灵（TFL）是一种高度持久的土壤颗粒除草剂，具有很强的吸附能力。本研究从历史上使用过农药的土壤中分离出微生物群落和细菌菌株，以评估它们在土壤中降解 TFL 的潜力。考虑了不同的生物修复技术来提高土壤中 TFL 降解的效果。这些技术包括：i）生物刺激，使用营养溶液（NS）；ii）生物增强，使用天然微生物群落（NMC）、从 NMC 中分离出的 7 种单个细菌菌株，以及由 7 种 TFL 降解细菌菌株组成的人工细菌群落（ABC）；iii）生物有效性增强，使用可生物降解的化合物，随机甲基化环糊精，RAMEB。使用 NS 进行生物刺激可导致 100 天后土壤中 TFL 的生物降解率达到 34%。当污染土壤接种 NMC 或 ABC 群落时，TFL 的损失分别增加到 62%和 74%，DT 值（污染物浓度降至初始值一半所需的时间）分别为 5.9 和 11 天。在土壤接种分离的单个细菌菌株的情况下，TFL 生物降解的程度范围很广，从 2.3%到 55%。最有效的细菌菌株是节杆菌（Arthrobacter aurescens）CTFL7，它以前在文献中没有被描述为一种 TFL 降解细菌。在存在 RAMEB 的情况下，还测试了 CTFL7 细菌的生物增强，导致除草剂生物降解率急剧增加到 88%，仅需 19 天即可达到 DT 值。环糊精以前从未用于增强 TFL 生物降解。进行了一项生态毒性测定，以确认所提出的生物修复技术也能够降低毒性。微毒测试（Microtox® test）表明，在用 A. aurescens CTF7 和 A. aurescens CTF7+RAMEB 处理后，最初具有急性毒性的 TFL 污染土壤在生物降解实验结束时变得无毒。
