Biomarkers such as functional gene mRNA (transcripts) and proteins (enzymes) provide direct proof of metabolic regulation during the reductive dechlorination (RD) of chlorinated ethenes (CEs). Yet, current models to simulate their spatiotemporal variability are not flexible enough to mimic the homologous behavior of RDase functional genes. To this end, we developed new enzyme-based kinetics to model the concentrations of CEs together with the transcript and enzyme levels during RD. First, the model was calibrated to existing microcosm data on RD of cis-DCE. The model mirrored the tceA and vcrA gene expression and the production of their enzymes in Dehalococcoides spp. Considering tceA and vcrA as homologous instead of nonhomologous improved fitting of the mRNA time series. Second, CEs and biomarker patterns were explored as a proof of concept under groundwater flow conditions, considering degraders occurring in immobile and mobile states. Under both microcosm and flow conditions, biomarker-rate relationships were nonlinear hysteretic because tceA and vcrA acted as homologous genes. The mobile biomarkers additionally undergo advective-dispersive transport, which increases the nonlinearity and makes the observed patterns even more challenging to interpret. The model offers a thorough mechanistic description of RD while also allowing simulation of spatiotemporal dynamic patterns of various key biomarkers in aquifers.

中文翻译：

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将基于酶的动力学整合到反应性运输模型中，以模拟氯化乙烯降解过程中生物标志物的时空动力学


功能性基因 mRNA（转录本）和蛋白质（酶）等生物标志物直接证明了氯化乙烯 （CE） 还原脱氯 （RD） 过程中的代谢调节。然而，当前模拟其时空变异性的模型不够灵活，无法模拟 RDase 功能基因的同源行为。为此，我们开发了新的基于酶的动力学来模拟 RD 期间 CEs 的浓度以及转录本和酶水平。首先，根据 cis-DCE 的 RD 的现有微观数据对模型进行校准。该模型反映了 tceA 和 vcrA 基因的表达以及它们在 Dehalococcoides spp 中的酶产生。将 tceA 和 vcrA 视为同源而不是非同源，改进了 mRNA 时间序列的拟合。其次，考虑到发生在不动和移动状态下的降解剂，探索了 CE 和生物标志物模式作为地下水流条件下的概念验证。在微观和流动条件下，生物标志物-率关系都是非线性滞后的，因为 tceA 和 vcrA 充当同源基因。移动生物标志物还经历了平流-分散传输，这增加了非线性，使观察到的模式更难解释。该模型提供了 RD 的全面机理描述，同时还允许模拟含水层中各种关键生物标志物的时空动态模式。