A simple model for the B12-riboswitch regulatory network in Escherichia coli is first described and the same analysis is applied when changing the strain to Salmonella enterica. Model validation is undertaken by linking the dynamics of the riboswitch model to bacterial growth and comparing the results obtained with in vivo experimental measurements. Measurements of bacterial growth are relatively straightforward to obtain experimentally, but experimental measurements relating to the operation of the riboswitch are more difficult. Using the validated model, sliding mode observer design methods are used to estimate BtuB given measurements of the concentration of vitamin B12. The sliding mode approach is selected because of its inherent robustness properties as well as for the ease of implementation. Validation of the estimates of BtuB produced by the observer is undertaken by comparing the BtuB and vitamin B12 concentrations estimated from the observer with green fluorescent protein production and the concentration of vitamin B12 obtained experimentally. These experimental results also provide further validation of the underpinning mathematical model. The results establish that using a sliding mode observer as a soft sensor is a useful approach to explore the operation of a vitamin B12 riboswitch given measurements of the concentration of vitamin B12.

中文翻译：

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使用滑模观测器根据测得的维生素 B12 浓度估算 BtuB 浓度。


首先描述了大肠杆菌中 B12-核糖开关调节网络的简单模型，并且在将菌株改为肠道沙门氏菌时应用了相同的分析。通过将核糖开关模型的动力学与细菌生长联系起来并将获得的结果与体内实验测量进行比较来进行模型验证。细菌生长的测量相对容易通过实验获得，但与核糖开关操作相关的实验测量更加困难。使用经过验证的模型，在给定维生素 B12 浓度测量值的情况下，使用滑模观测器设计方法来估计 BtuB。选择滑模方法是因为其固有的鲁棒性特性以及易于实现。通过将观察者估计的 BtuB 和维生素 B12 浓度与绿色荧光蛋白产量和实验获得的维生素 B12 浓度进行比较，对观察者产生的 BtuB 估计值进行验证。这些实验结果还进一步验证了基础数学模型。结果表明，在测量维生素 B12 浓度的情况下，使用滑模观测器作为软传感器是探索维生素 B12 核糖开关操作的有用方法。