Division of Soil and Water Management, Department of Earth and Environmental Sciences, Faculty of Bioscience Engineering, KU Leuven, Kasteelpark Arenberg 20, 3001, Leuven, Belgium,
Appl Microbiol Biotechnol. 2013 Nov;97(22):9837-46. doi: 10.1007/s00253-013-4690-7. Epub 2013 Jan 22.
In nature, pesticides are often present as micropollutants with concentrations too low for efficient biodegradation and growth of heterotrophic pollutant-degrading bacteria. Instead, organic carbon present in environmental dissolved organic matter (eDOM) constitutes the main carbon source in nature. Information on how natural organic carbon affects degradation of pollutants and micropollutants, in particular, is however poor. Linuron-degrading Variovorax sp. strains SRS16, WDL1, and PBLH6 and a triple-species bacterial consortium, from which WDL1 originated, were examined for their ability to degrade linuron at micropollutant concentrations and the effect hereon of different eDOM formulations of varying biodegradability as supplementary C-source was explored. Individual strains and the consortium degraded linuron at initial concentrations as low as 1 μg L(-1) till concentrations below 4 ng L(-1). Degradation kinetics differed among strains with rates that differed up to 70-fold at the lowest linuron concentrations and with lag phases ranging from 0 to 7 days. Linuron biodegradation by the individual strains was inhibited by an easily biodegradable compound such as citrate but stimulated by eDOM at a linuron concentration of 10 mg L(-1). Effects were strongly reduced or became non-existent at micropollutant linuron concentrations. Effects of eDOM on degradation at 10 mg L(-1) linuron by WDL1 were reduced when WDL1 was incubated together with its original consortium members. This is the first report on eDOM effects on degradation of pesticides at micropollutant concentrations and indicates these effects are limited and depend on linuron and eDOM concentrations, eDOM quality, and the bacterial culture.
在自然界中，农药通常作为浓度太低而无法有效生物降解和异养污染物降解细菌生长的微量污染物存在。相反，环境溶解有机物质（eDOM）中存在的有机碳是自然界中主要的碳源。然而，关于天然有机碳如何影响污染物和微量污染物的降解的信息却很少。本研究检测了林草隆降解菌 Variovorax sp. 菌株 SRS16、WDL1 和 PBLH6 以及源自 WDL1 的三物种细菌混合培养物在微量污染物浓度下降解林草隆的能力，以及不同可生物降解性的不同 eDOM 配方作为补充 C 源对其的影响。单个菌株和混合培养物在初始浓度低至 1μg/L 时就可以降解林草隆，直到浓度低于 4ng/L。菌株之间的降解动力学存在差异，在最低林草隆浓度下，速率差异高达 70 倍，且迟滞期从 0 到 7 天不等。在 10mg/L 的林草隆浓度下，易生物降解的化合物如柠檬酸盐会抑制单个菌株对林草隆的生物降解，但会刺激 eDOM 对林草隆的生物降解。在微量污染物林草隆浓度下，这些影响会大大减弱或消失。在 10mg/L 的林草隆浓度下，WDL1 与原始混合培养物成员一起孵育时，eDOM 对 WDL1 降解的影响会降低。这是首次报道 eDOM 对微量污染物浓度下农药降解的影响，表明这些影响是有限的，并取决于林草隆和 eDOM 浓度、eDOM 质量以及细菌培养物。
