Anderlei Tibor, Mrotzek Christian, Bartsch Stefan, Amoabediny Ghassem, Peter Cyril P, Büchs Jochen
Biochemical Engineering, RWTH Aachen University, Worringerweg 1, 52056 Aachen, Germany.
Biotechnol Bioeng. 2007 Dec 1;98(5):999-1007. doi: 10.1002/bit.21490.
In this paper a novel and easily applied method to measure the mass transfer resistance of the sterile closures (e.g. cotton plug) of shaken bioreactors is introduced. This method requires no investment in special equipment (e.g. an oxygen sensor) and can be performed with the materials usually available in typical laboratories. The method is based on the model of Henzler et al. (1986), which mechanistically describes mass transfer through the sterile closure of a shaken bioreactor based on diffusion coupled with Stefan convection. The concentration dependency of the multi-component diffusion coefficients is taken into account. The water loss from two equivalent shaken bioreactors equipped with sterile closures during several days of shaking is measured. One flask contains distilled water, the other a saturated salt solution. From the water evaporation rate in each of the two flasks, the new model presented calculates the relative humidity in the environment, the average diffusion coefficient of oxygen in the sterile closure (D(O2)), and the diffusion coefficient of carbon dioxide (D(CO2)) . The diffusion coefficient of carbon dioxide (D(CO2)) only depends on the density and material properties of the sterile closure and not on the gas concentrations and is, therefore, an ideal parameter for the characterization of the mass transfer resistance. This new method is validated experimentally by comparing the diffusion coefficient of oxygen (D(O2)) to a measurement by the classic dynamic method; and by comparing the calculated relative humidity in the environment to a humidity sensor measurement.
本文介绍了一种新颖且易于应用的方法，用于测量摇床式生物反应器无菌密封件（如棉塞）的传质阻力。该方法无需投资购买特殊设备（如氧气传感器），并且可以使用典型实验室中通常可用的材料来进行。该方法基于Henzler等人（1986年）的模型，该模型从机理上描述了基于扩散与斯特凡对流耦合通过摇床式生物反应器无菌密封件的传质过程。考虑了多组分扩散系数的浓度依赖性。测量了两个配备无菌密封件的等效摇床式生物反应器在几天摇动过程中的水分损失。一个烧瓶装有蒸馏水，另一个装有饱和盐溶液。根据两个烧瓶中各自的水蒸发速率，所提出的新模型计算环境中的相对湿度、无菌密封件中氧气的平均扩散系数（D(O2)）以及二氧化碳的扩散系数（D(CO2)）。二氧化碳的扩散系数（D(CO2)）仅取决于无菌密封件的密度和材料特性，而不取决于气体浓度，因此是表征传质阻力的理想参数。通过将氧气的扩散系数（D(O2)）与经典动态方法的测量值进行比较，以及将计算出的环境中的相对湿度与湿度传感器的测量值进行比较，对这种新方法进行了实验验证。
