操作條件對酵母菌/牛血清蛋白雙成份懸浮液之掃流微過濾性能之影響

Effects of Operating Conditions on the Performance of Cross-Flow Microfiltration of Yeast/BSA Binary Suspension

黃信杰(Hsin-Chieh Hwang)

指導教授 ： 黃國楨

淡江大學/工學院/化學工程與材料工程學系碩士班/碩士(2005年)

https://doi.org/10.6846/TKU.2005.00164

摘要

本研究以酵母菌（Yeast）來模擬生物發酵槽中之培養菌，再加入牛血清蛋白（BSA）配置成雙成份之懸浮液，來探討酵母菌與牛血清蛋白懸浮液的掃流微過濾特性。我們以適當薄膜阻擋懸浮溶液中的酵母菌，而部分牛血清蛋白質則可通過薄膜，以達到分離的效果。藉由量測不同的pH值及操作條件下的濾液通量，以及牛血清蛋白質的阻擋率，並分析濾餅的性質，以期找出懸浮液性質對分離效率的影響。
由實驗結果發現，由於酵母菌等電位點接近pH = 3.0，所以在此條件下，酵母菌會發生聚集現象，使得其穩定濾速比pH = 5.0和pH = 7.0高出很多，但是對牛血清蛋白的阻擋率卻是最低的。而pH = 5.0和pH = 7.0環境之下，pH = 5.0濾速稍偏低一點、阻擋率則偏高一些，這是由於pH = 5.0時，BSA有凝聚的現象發生，使得濾餅或膜孔被BSA聚集團所阻塞，造成有比較低的濾液流量和比較高的阻擋率。由實驗得知pH＝3.0之懸浮液，在高掃流速度、低過濾壓差下會有最好的分離效率。
本研究藉由過濾基本公式和力平衡方程式，推導一擬穩定濾速與操作條件的關係式。並根據濃度極化模式、深層過濾之粒子標準捕獲方程式，再考慮剪應力對巨分子運動的影響，進而得到一理論式，藉由此理論式子來估計巨分子之阻擋率，所得到的估計值符合實驗趨勢。

關鍵字

掃流微過濾 ； 蛋白質純化 ； pH值 ； 分離效率

並列摘要

In this study, yeast cells are used to simulate the microbes in a fermentation tank. Yeast cell and BSA are suspended in a de-ionized water to prepare the binary suspension used in experiments. Yeast cells are retained by the filter membrane during a filtration, while some BSA molecules may permeate through the filter cake and the membrane into filtrate. The filtration rate, the retention of BSA and the cake properties under various operating conditions are measured and discussed.
The experimental results show that an aggregation of yeast cells occurs at pH 3 (near its isoelectric point), and the steady filtration rate is therefore quite higher than those at pH 5 and pH 7. However, the retention of BSA is the lowest at pH 3. Since BSA molecules coagulate with each other at pH 5, the BSA aggregates may foul in the cake or in the membrane pores. Therefore, the filtration rate is lower and the retention is higher at pH 5 than those at pH 7. A suspension at pH 3 under high cross-flow velocity and low filtration pressure can be concluded as the optimum operating condition.
Based on the basic filtration equation and the force balance equation, the relationships among the pseudo-steady filtration rate and operating conditions can be derived and used for flux prediction. The estimated filtration rate agrees fairly well with experimental data. Furthermore, according to the concentration polarization model, the standard capture equation for depth filtration and the effect of shear stress on the protein migration, a theoretical equation is obtained to estimate the retention of protein. The protein retentions under various conditions can be estimated accurately.

並列關鍵字

cross-flow microfiltration ； protein purification ； pH value ； separation efficiency

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