Department of Biological Systems Engineering, Washington State University, Pullman, Washington 99164, USA.
Biotechnol Bioeng. 2012 Jul;109(7):1755-68. doi: 10.1002/bit.24433. Epub 2012 Jan 23.
Numerical simulations and experimental validation were performed to understand the effects of hydrodynamics on pellet formation and cellulase production by filamentous T. reesei. The constructed model combined a steady-state multiple reference frame (MRF) approach describing mechanical mixing, oxygen mass transfer, and non-Newtonian flow field with a transient sliding mesh approach and kinetics of oxygen consumption, pellet formation, and enzyme production. The model was experimentally validated at various agitation speeds in a two-impeller Rushton turbine fermentor. Results from simulation and experimentation showed that higher agitation speeds led to increases in the pellet diameter and the proportion of pelletized (vs. filamentous) forms of the biomass. It also led to increase in dissolved oxygen mass transfer rate in shear-thinning fluid and cellulase productivity. The extent of these increases varied considerably among agitation speeds. Pellet formation and morphology were presumably affected within a viscosity-dependent shear-rate range. Cellulase activity and cell viability were shown to be sensitive to impeller shear. A maximum cellulase activity of 3.5 IU/mL was obtained at 400 rpm, representing a twofold increase over that at 100 rpm.
进行了数值模拟和实验验证，以了解水动力对丝状 T.reesei 颗粒形成和纤维素酶生产的影响。所构建的模型将稳态多参考框架 (MRF) 方法与瞬态滑网格方法和氧消耗、颗粒形成和酶生产动力学相结合，该方法描述了机械混合、氧传质和非牛顿流场。该模型在具有双叶轮 Rushton 涡轮发酵罐的各种搅拌速度下进行了实验验证。模拟和实验结果表明，较高的搅拌速度会导致颗粒直径和颗粒化（与丝状）生物质比例增加。它还导致剪切稀化流体中的溶解氧传质速率和纤维素酶生产力增加。这些增加的程度在搅拌速度之间有很大差异。颗粒形成和形态可能会受到依赖于粘度的剪切率范围的影响。纤维素酶活性和细胞活力被证明对叶轮剪切敏感。在 400rpm 时获得了 3.5IU/mL 的最大纤维素酶活性，比在 100rpm 时增加了一倍。
