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：

---

使用滑动模式观察者，根据测量的维生素B12浓度估算BtuB浓度。

首先描述了大肠埃希氏菌中B12-核糖开关调控网络的简单模型，并且在将菌株改为小肠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，并与体内实验测量结果进行比较，进行模型验证。细菌生长的测量相对容易地通过实验获得，但是与核糖开关的操作有关的实验测量更加困难。使用经过验证的模型，在提供维生素B12浓度测量值的情况下，可使用滑模观察器设计方法来估算BtuB。选择滑模方法是因为其固有的鲁棒性以及易于实现。通过比较观察者估计的BtuB和维生素B12浓度与绿色荧光蛋白的产生以及实验获得的维生素B12的浓度，来验证观察者产生的BtuB的估计值。这些实验结果还为基础数学模型提供了进一步的验证。结果表明，使用给定的维生素B12浓度测量值，使用滑动模式观察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。这些实验结果还为基础数学模型提供了进一步的验证。结果表明，使用给定的维生素B12浓度测量值，使用滑动模式观察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。这些实验结果还为基础数学模型提供了进一步的验证。结果表明，使用给定的维生素B12浓度测量值，使用滑动模式观察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。