Horemans Benjamin, Bers Karolien, Ruiz Romero Erick, Pose Juan Eva, Dunon Vincent, De Mot René, Springael Dirk
Division of Soil and Water Management, KU Leuven, Heverlee, Belgium.
Laboratory of Soil Ecology, Cinvestav, Mexico City, Mexico.
Appl Environ Microbiol. 2016 Apr 18;82(9):2843-2853. doi: 10.1128/AEM.04018-15. Print 2016 May.
The abundance of libA, encoding a hydrolase that initiates linuron degradation in the linuron-metabolizing Variovorax sp. strain SRS16, was previously found to correlate well with linuron mineralization, but not in all tested environments. Recently, an alternative linuron hydrolase, HylA, was identified in Variovorax sp. strain WDL1, a strain that initiates linuron degradation in a linuron-mineralizing commensal bacterial consortium. The discovery of alternative linuron hydrolases poses questions about the respective contribution and competitive character of hylA- and libA-carrying bacteria as well as the role of linuron-mineralizing consortia versus single strains in linuron-exposed settings. Therefore, dynamics of hylA as well as dcaQ as a marker for downstream catabolic functions involved in linuron mineralization, in response to linuron treatment in agricultural soil and on-farm biopurification systems (BPS), were compared with previously reported libA dynamics. The results suggest that (i) organisms containing either libA or hylA contribute simultaneously to linuron biodegradation in the same environment, albeit to various extents, (ii) environmental linuron mineralization depends on multispecies bacterial food webs, and (iii) initiation of linuron mineralization can be governed by currently unidentified enzymes.
A limited set of different isofunctional catabolic gene functions is known for the bacterial degradation of the phenylurea herbicide linuron, but the role of this redundancy in linuron degradation in environmental settings is not known. In this study, the simultaneous involvement of bacteria carrying one of two isofunctional linuron hydrolysis genes in the degradation of linuron was shown in agricultural soil and on-farm biopurification systems, as was the involvement of other bacterial populations that mineralize the downstream metabolites of linuron hydrolysis. This study illustrates the importance of the synergistic metabolism of pesticides in environmental settings.
在能代谢利谷隆的变栖菌属菌株SRS16中，编码启动利谷隆降解的水解酶的libA丰度，此前发现与利谷隆矿化密切相关，但并非在所有测试环境中均如此。最近，在变栖菌属菌株WDL1中鉴定出另一种利谷隆水解酶HylA，该菌株在一个能使利谷隆矿化的共生细菌群落中启动利谷隆降解。替代利谷隆水解酶的发现引发了关于携带hylA和libA的细菌各自的贡献和竞争特性，以及在接触利谷隆的环境中利谷隆矿化群落与单一菌株的作用等问题。因此，将hylA以及作为参与利谷隆矿化的下游分解代谢功能标志物的dcaQ在农业土壤和农场生物净化系统（BPS）中对利谷隆处理的响应动态，与先前报道的libA动态进行了比较。结果表明：（i）含有libA或hylA的生物体在同一环境中同时对利谷隆生物降解有贡献，尽管程度不同；（ii）环境中的利谷隆矿化取决于多物种细菌食物网；（iii）利谷隆矿化的启动可能受目前尚未鉴定的酶控制。
对于细菌降解苯基脲类除草剂利谷隆，已知一组有限的不同同功分解代谢基因功能，但这种冗余在环境中利谷隆降解中的作用尚不清楚。在本研究中，表明在农业土壤和农场生物净化系统中，携带两个同功利谷隆水解基因之一的细菌同时参与利谷隆降解，利谷隆水解下游代谢产物矿化的其他细菌种群也参与其中。本研究说明了农药在环境中的协同代谢的重要性。
