Technical University of Munich , Chair of Analytical Chemistry and Water Chemistry , Marchioninistrasse 17 , 81377 Munich , Germany.
Helmholtz Zentrum München , Institute of Groundwater Ecology , Ingolstädter Landstrasse 1 , 85764 Neuherberg , Germany.
Environ Sci Technol. 2019 Feb 5;53(3):1186-1196. doi: 10.1021/acs.est.8b02498. Epub 2019 Jan 7.
We present a framework to model microbial transformations in chemostats and retentostats under transient or quasi-steady state conditions. The model accounts for transformation-induced isotope fractionation and mass-transfer across the cell membrane. It also verifies that the isotope fractionation ϵ can be evaluated as the difference of substrate-specific isotope ratios between inflow and outflow. We explicitly considered that the dropwise feeding of substrate into the reactor at very low dilution rates leads to transient behavior of concentrations and transformation rates and use this information to validate conditions under which a quasi-steady state treatment is justified. We demonstrate the practicality of the code by modeling a chemostat experiment of atrazine degradation at low dilution/growth rates by the strain Arthrobacter aurescens TC1. Our results shed light on the interplay of processes that control biodegradation and isotope fractionation of contaminants at low (μg/L) concentration levels. With the help of the model, an estimate of the mass-transfer coefficient of atrazine through the cell membrane was achieved (0.0025 s).
我们提出了一个框架，用于在暂态或准稳态条件下对恒化器和恒浊器中的微生物转化进行建模。该模型考虑了转化诱导的同位素分馏和跨细胞膜的质量传递。它还验证了同位素分馏ϵ可以评估为入口和出口之间基质特异性同位素比的差异。我们明确考虑了在非常低的稀释率下将基质滴入反应器中导致浓度和转化速率的暂态行为，并利用这些信息来验证准稳态处理合理的条件。我们通过模拟低稀释/生长速率下菌株 Arthrobacter aurescens TC1 对莠去津的降解的恒化器实验，证明了代码的实用性。我们的结果揭示了控制生物降解和污染物同位素分馏的过程在低（μg/L）浓度水平下相互作用的情况。借助该模型，实现了莠去津通过细胞膜的传质系数的估计（0.0025 s）。
