University Perpignan Via Domitia, Biocapteurs-Analyses-Environnement, 66860 Perpignan, France; Laboratoire de Biodiversité et Biotechnologies Microbiennes, USR 3579 Sorbonne Universités (UPMC) Paris 6 et CNRS Observatoire Océanologique, 66650, Banyuls-sur-Mer, France.
Agroécologie, INRAE, Institut Agro, Unv. Bourgogne, University Bourgogne Franche-Comté, F-21000, Dijon, France.
Environ Sci Pollut Res Int. 2023 Jan;30(4):9932-9944. doi: 10.1007/s11356-022-22801-7. Epub 2022 Sep 6.
4-hydroxyphenylpyruvate dioxygenase (HPPD) is the molecular target of β-triketone herbicides in plants. This enzyme, involved in the tyrosine pathway, is also present in a wide range of living organisms, including microorganisms. Previous studies, focusing on a few strains and using high herbicide concentrations, showed that β-triketones are able to inhibit microbial HPPD. Here, we measured the effect of agronomical doses of β-triketone herbicides on soil bacterial strains. The HPPD activity of six bacterial strains was tested with 1× or 10× the recommended field dose of the herbicide sulcotrione. The selected strains were tested with 0.01× to 15× the recommended field dose of sulcotrione, mesotrione, and tembotrione. Molecular docking was also used to measure and model the binding mode of the three herbicides with the different bacterial HPPD. Our results show that responses to herbicides are strain-dependent with Pseudomonas fluorescens F113 HPPD activity not inhibited by any of the herbicide tested, when all three β-triketone herbicides inhibited HPPD in Bacillus cereus ATCC14579 and Shewanella oneidensis MR-1. These responses are also molecule-dependent with tembotrione harboring the strongest inhibitory effect. Molecular docking also reveals different binding potentials. This is the first time that the inhibitory effect of β-triketone herbicides is tested on environmental strains at agronomical doses, showing a potential effect of these molecules on the HPPD enzymatic activity of non-target microorganisms. The whole-cell assay developed in this study, coupled with molecular docking analysis, appears as an interesting way to have a first idea of the effect of herbicides on microbial communities, prior to setting up microcosm or even field experiments. This methodology could then largely be applied to other family of pesticides also targeting an enzyme present in microorganisms.
4-羟基苯丙酮酸双加氧酶 (HPPD) 是植物中β-三酮类除草剂的分子靶标。这种参与酪氨酸途径的酶也存在于包括微生物在内的广泛的生物体中。以前的研究集中在少数几个菌株上，并使用高浓度的除草剂，表明β-三酮类能够抑制微生物 HPPD。在这里，我们测量了农业剂量的β-三酮类除草剂对土壤细菌菌株的影响。用推荐田间剂量的除草剂磺草酮 1×或 10×测试了 6 个细菌菌株的 HPPD 活性。用推荐田间剂量的磺草酮、噻酮和涕灭威的 0.01×至 15×测试了选定的菌株。还使用分子对接来测量和模拟三种除草剂与不同细菌 HPPD 的结合模式。我们的结果表明，除草剂的反应取决于菌株，荧光假单胞菌 F113 的 HPPD 活性不受测试的任何一种除草剂的抑制，而三种β-三酮类除草剂都抑制了蜡状芽孢杆菌 ATCC14579 和希瓦氏菌 MR-1 的 HPPD。这些反应也取决于分子，涕灭威具有最强的抑制作用。分子对接还揭示了不同的结合潜力。这是第一次在农业剂量下测试β-三酮类除草剂对环境菌株的抑制作用，表明这些分子对非靶标微生物 HPPD 酶活性有潜在影响。本研究中开发的全细胞测定法与分子对接分析相结合，似乎是在进行微宇宙甚至田间实验之前，了解除草剂对微生物群落影响的一种有趣方法。然后，这种方法可以广泛应用于其他也针对微生物中存在的酶的农药家族。
