The frequent exposure of agricultural soils to pesticides can lead to microbial adaptation, including the development of dedicated microbial populations that utilize the pesticide compound as a carbon and energy source. Soil from an agricultural field in Halen (Belgium) with a history of linuron exposure has been studied for its linuron-degrading bacterial populations at two time points over the past decade and Variovorax was appointed as a key linuron degrader. Like most studies on pesticide degradation, these studies relied on isolates that were retrieved through bias-prone enrichment procedures and therefore might not represent the in situ active pesticide-degrading populations. In this study, we revisited the Halen field and applied, in addition to enrichment-based isolation, DNA stable isotope probing (DNA-SIP), to identify in situ linuron-degrading bacteria in linuron-exposed soil microcosms. Linuron dissipation was unambiguously linked to Variovorax and its linuron catabolic genes and might involve the synergistic cooperation between two species. Additionally, two novel linuron-mineralizing Variovorax isolates were obtained with high 16S rRNA gene sequence similarity to strains isolated from the same field a decade earlier. The results confirm Variovorax as a prime in situ degrader of linuron in the studied agricultural field soil and corroborate the genus as key for maintaining the genetic memory of linuron degradation functionality in that field.

中文翻译：

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DNA-SIP 和重复分离证实 Variovorax 是维持农业土壤中 linuron 生物降解遗传记忆的关键生物

农业土壤频繁接触杀虫剂可导致微生物适应，包括开发利用杀虫剂化合物作为碳和能源的专用微生物种群。在过去十年中的两个时间点，研究了来自 Halen（比利时）农田的土壤中的 linuron 降解细菌种群，Variovorax 被指定为关键的 linuron 降解剂。与大多数关于农药降解的研究一样，这些研究依赖于通过偏倚富集程序检索的分离物，因此可能不代表原位活跃的农药降解种群。在这项研究中，我们重新审视了 Halen 领域，并应用了除了基于富集的分离、DNA 稳定同位素探测 (DNA-SIP)、鉴定 linuron 暴露土壤微观世界中的原位 linuron 降解细菌。Linuron 耗散与 Variovorax 及其分解代谢基因明确相关，可能涉及两个物种之间的协同合作。此外，还获得了两种新的 linuron 矿化 Variovorax 分离株，其 16S rRNA 基因序列与十年前从同一领域分离的菌株具有高度相似性。结果证实 Variovorax 是所研究的农田土壤中亚麻醛原位降解剂的主要原位降解剂，并证实该属是维持该田间亚麻醛降解功能遗传记忆的关键。此外，还获得了两种新的 linuron 矿化 Variovorax 分离株，其 16S rRNA 基因序列与十年前从同一领域分离的菌株具有高度相似性。结果证实 Variovorax 是所研究的农田土壤中亚麻醛原位降解剂的主要原位降解剂，并证实该属是维持该田间亚麻醛降解功能遗传记忆的关键。此外，还获得了两种新的 linuron 矿化 Variovorax 分离株，其 16S rRNA 基因序列与十年前从同一领域分离的菌株具有高度相似性。结果证实 Variovorax 是所研究的农田土壤中亚麻醛原位降解剂的主要原位降解剂，并证实该属是维持该田间亚麻醛降解功能遗传记忆的关键。