Jüsten P, Paul G C, Nienow A W, Thomas C R
Centre for Biochemical Engineering, School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom.
Biotechnol Bioeng. 1996 Dec 20;52(6):672-84. doi: 10.1002/(SICI)1097-0290(19961220)52:6<672::AID-BIT5>3.0.CO;2-L.
The influence of the agitation conditions on the morphology of Penicillium chrysogenum (freely dispersed and aggregated forms) was examined using radial (Rushton turbines and paddles), axial (pitched blades, propeller, and Prochem Maxflow T), and counterflow impellers (Intermig). Culture broth was taken from a continuous fermentation at steady state and was agitated for 30 min in an ungassed vessel of 1.4-L working volume. The power inputs per unit volume of liquid in the tank, P/V(L), ranged from 0.6 to 6 kW/m(3). Image analysis was used to measure mycelial morphology. To characterize the intensity of the damage caused by different impellers, the mean total hyphal length (freely dispersed form) and the mean projected area (all dispersed types, i.e., also including aggregates) were used. [In this study, breakage of aggregates was taken into account quantitatively for the first time.]At 1.4-L scale and a given P/V(L), changes in the morphology depended significantly on the impeller geometry. However, the morphological data (obtained with different geometries and various P/V(L)) could be correlated on the basis of equal tip speed and two other, less simple, mixing parameters. One is based on the specific energy dissipation rate in the impeller region, which is simply related to P/V(L) and particular impeller geometrical parameters. The other which is developed in this study is based on a combination of the specific energy dissipation rate in the impeller swept volume and the frequency of mycelial circulation through that volume. For convenience, the function arising from this concept is called the "energy dissipation/circulation" function.To test the broader validity of these correlations, scale-up experiments were carried out in mixing tanks of 1.4, 20, and 180 L using a Rushton turbine and broth from a fed-batch fermentation. The energy dissipation/circulation function was a reasonable correlating parameter for hyphal damage over this range of scales, whereas tip speed, P/V(L), and specific energy dissipation rate in the impeller region were poor. Two forms of the energy dissipation/circulation function were considered, one of which additionally allowed for the numbers of vortices behind the blades of each impeller type. Although both forms were successful at correlating the data for the standard impeller designs considered here, there was preliminary evidence that allowing for the vortices would be valuable. (c) 1996 John Wiley & Sons, Inc.
使用径向（Rushton涡轮和桨叶）、轴向（斜叶桨、螺旋桨和Prochem Maxflow T）和逆流搅拌器（Intermig）研究了搅拌条件对产黄青霉形态（自由分散和聚集形式）的影响。发酵液取自稳态连续发酵，在工作体积为1.4 L的未通气容器中搅拌30分钟。罐中每单位液体体积的功率输入P/V(L)范围为0.6至6 kW/m³。采用图像分析来测量菌丝形态。为了表征不同搅拌器造成的损伤强度，使用了平均总菌丝长度（自由分散形式）和平均投影面积（所有分散类型，即也包括聚集体）。[在本研究中，首次对聚集体的破碎进行了定量考虑。]在1.4 L规模和给定的P/V(L)下，形态变化显著取决于搅拌器几何形状。然而，基于相同的叶端速度以及另外两个不太简单的混合参数，可以将（通过不同几何形状和各种P/V(L)获得的）形态学数据关联起来。一个基于搅拌器区域的比能耗散率，它与P/V(L)和特定搅拌器几何参数简单相关。本研究中提出的另一个参数基于搅拌器扫掠体积内的比能耗散率与菌丝体通过该体积的循环频率的组合。为方便起见，由该概念产生的函数称为“能耗散/循环”函数。为了检验这些关联的更广泛有效性，使用Rushton涡轮和补料分批发酵的发酵液，在1.4、20和180 L的搅拌罐中进行了放大实验。在这个规模范围内，能耗散/循环函数是菌丝损伤的合理关联参数，而叶端速度、P/V(L)和搅拌器区域的比能耗散率则不佳。考虑了能耗散/循环函数的两种形式，其中一种还考虑了每种搅拌器类型叶片后方的漩涡数量。尽管这两种形式都成功地关联了此处考虑的标准搅拌器设计的数据，但有初步证据表明考虑漩涡将是有价值的。(c) 1996 John Wiley & Sons, Inc.
