Paul GC, Nienow AW, Thomas CR
Centre for Bioprocess Engineering, School of Chemical Engineering, The University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom.
Biotechnol Bioeng. 1998 Sep 20;59(6):762-75. doi: 10.1002/(sici)1097-0290(19980920)59:6<762::aid-bit13>3.0.co;2-7.
The influence of the agitation conditions on the growth, morphology, vacuolation, and productivity of Penicillium chrysogenum has been examined in 6 L fed-batch fermentations. A standard Rushton turbine, a four-bladed paddle, and a six-bladed pitched blade impeller were compared. Power inputs per unit volume of liquid, P/VL, ranged from 0.35 to 7.4 kW/m3. The same fermentation protocol was used in each fermentation, including holding the dissolved oxygen concentration above 40% air saturation by gas blending. The mean projected area (for all dispersed types, including clumps) and the clump roughness were used to characterize the morphology. Consideration of clumps was vital as these were the predominant morphological form. For a given impeller, the batch-phase specific growth rates and the overall biomass concentrations increased with agitation intensity. Higher fragmentation at higher speeds was assumed to have promoted growth through increased formation of new growing tips. The mean projected area increased during the rapid growth phase followed by a sharp decrease to a relatively constant value dependent on the agitation conditions. The higher the speed, the lower the projected area for a given impeller type. The proportion by volume of hyphal vacuoles and empty regions decreased with speed, possibly due to fragmentation in the vacuolated regions. The specific penicillin production rate was generally higher with lower impeller speed for a given impeller type. The highest value of penicillin production as well as its rate was obtained using the Rushton turbine impeller at the lowest speed. At given P/VL, changes in morphology, specific growth rate, and specific penicillin production rate depended on impeller geometry. The morphological data could be correlated with either tip speed or the "energy dissipation/circulation function," but a reasonable correlation of the specific growth rate and specific production rate was only possible with the latter. Copyright 1998 John Wiley & Sons, Inc.
在6L补料分批发酵中，研究了搅拌条件对产黄青霉生长、形态、空泡化及生产力的影响。比较了标准的 Rushton 涡轮搅拌器、四叶桨式搅拌器和六叶斜叶涡轮搅拌器。每单位液体体积的功率输入（P/VL）范围为0.35至7.4kW/m³。每次发酵均采用相同的发酵方案，包括通过气体混合使溶解氧浓度保持在空气饱和度的40%以上。用平均投影面积（针对所有分散类型，包括菌团）和菌团粗糙度来表征形态。考虑菌团至关重要，因为它们是主要的形态形式。对于给定的搅拌器，分批培养阶段的比生长速率和总生物量浓度随搅拌强度的增加而增加。假定在较高速度下更高程度的破碎通过增加新生长尖端的形成促进了生长。在快速生长阶段平均投影面积增加，随后急剧下降至取决于搅拌条件的相对恒定值。对于给定的搅拌器类型，速度越高，投影面积越低。菌丝空泡和空区域的体积比例随速度降低，这可能是由于空泡化区域的破碎。对于给定的搅拌器类型，较低的搅拌器速度通常使青霉素比生产速率更高。使用最低速度的 Rushton 涡轮搅拌器时，青霉素产量及其速率达到最高值。在给定的P/VL下，形态、比生长速率和青霉素比生产速率的变化取决于搅拌器几何形状。形态数据可以与叶尖速度或“能量耗散/循环函数”相关，但只有后者才能使比生长速率和比生产速率有合理的相关性。版权所有1998约翰威立父子公司。
