Evaluation of glucose diffusion coefficient through cell layers for the kinetic study of an immobilized cell-bioreactor
Evaluation of glucose diffusion coefficient through cell layers for the kinetic study of an immobilized cell-bioreactor
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DOI：
10.1016/s0009-2509(96)80002-9
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发表时间：
1996-04-01
影响因子：
4.7
通讯作者：
DelBorghi, M
中科院分区：
文献类型：
--
作者：
Converti, A;Casagrande, M;DelBorghi, M
本研究的目的是通过酿酒酵母生物膜，厚度范围从0.02至1.60毫米的葡萄糖的扩散系数的评估，以进行宏观动力学研究的酒精发酵的固定化细胞生物反应器提供了不同的孔隙率的矩阵。在18 ℃和30 ℃下计算出的有效平均扩散系数分别为1.39 × 10（-6）和1.44 × 10（-6）cm（2）s（-1），与生物膜厚度没有明显的依赖性。这些值约为相同温度下在水中计算的值的20%。葡萄糖在30摄氏度下通过生物膜的扩散系数已被用来进行扩散，对流和生物反应质量速度之间的比较，沿着一个固定床柱进料淀粉水解物溶液。虽然通过生物膜的扩散是限制步骤，但生物质在高停留时间下在载体孔内大量生长，使得生物膜的最表面活性层足以几乎完全转化进料的基质。在低停留时间下，该系统不能经受底物过载的明显情况。
The aim of this study is the evaluation of the diffusion coefficient of glucose through Saccharomyces cerevisiae biofilms, with thickness ranging from 0.02 to 1.60 mm, in order to carry out the macrokinetic study of alcoholic fermentations in immobilized cell bioreactors provided with matrices with varying porosity. Effective average diffusivities of 1.39 x 10(-6) and 1.44 x 10(-6) cm(2) s(-1) have been calculated at 18 and 30 degrees C, respectively, with no appreciable dependence on biofilm thickness. These values are about 20% of those calculated in water at the same temperatures. The glucose diffusion coefficient through the biofilm at 30 degrees C has been used to carry out a comparison between diffusion, convection and bioreaction mass velocities along a fixed-bed column fed with starch hydrolysate solutions. Although diffusion through the biofilm is the limiting step, biomass grows so abundantly within the support pores at high residence time that the most superficial active layers of biofilm are enough to transform nearly completely the substrate fed. At low residence time the system is not able to stand an evident situation of substrate overloading.