Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia, USA.
Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee, USA.
Biotechnol Bioeng. 2021 Dec;118(12):4678-4686. doi: 10.1002/bit.27930. Epub 2021 Sep 8.
Chemotactic bacteria sense and respond to temporal and spatial gradients of chemical cues in their surroundings. This phenomenon plays a critical role in many microbial processes such as groundwater bioremediation, microbially enhanced oil recovery, nitrogen fixation in legumes, and pathogenesis of the disease. Chemical heterogeneity in these natural systems may produce numerous competing signals from various directions. Predicting the migration behavior of bacterial populations under such conditions is necessary for designing effective treatment schemes. In this study, experimental studies and mathematical models are reported for the chemotactic response of Escherichia coli to a combination of attractant (α-methylaspartate) and repellent (NiCl ), which bind to the same transmembrane receptor complex. The model describes the binding of chemoeffectors and phosphorylation of the kinase in the signal transduction mechanism. Chemotactic parameters of E. coli (signaling efficiency , stimuli sensitivity coefficient , and repellent sensitivity coefficient ) were determined by fitting the model with experimental results for individual stimuli. Interestingly, our model naturally identifies NiCl as a repellent for . The model is capable of describing quantitatively the response to the individual attractant and repellent, and correctly predicts the change in direction of bacterial population migration for competing stimuli with a twofold increase in repellent concentration.
趋化细菌感知并响应其周围环境中化学线索的时间和空间梯度。这种现象在许多微生物过程中起着关键作用，例如地下水生物修复、微生物强化采油、豆类中的氮固定以及疾病的发病机制。在这些自然系统中，化学异质性可能会从各个方向产生许多竞争信号。在这种情况下预测细菌种群的迁移行为对于设计有效的处理方案是必要的。在这项研究中，报道了实验研究和数学模型，用于研究大肠杆菌对吸引剂（α-甲基天冬氨酸）和排斥剂（NiCl ）的组合的趋化反应，它们结合到相同的跨膜受体复合物上。该模型描述了趋化效应物的结合和信号转导机制中激酶的磷酸化。通过将模型与单个刺激的实验结果拟合，确定了大肠杆菌的趋化参数（信号效率 、刺激敏感性系数和排斥敏感性系数）。有趣的是，我们的模型自然将 NiCl 识别为 的排斥剂。该模型能够定量描述对单个吸引剂和排斥剂的响应，并正确预测在排斥剂浓度增加一倍时竞争刺激物对细菌种群迁移方向的变化。
