ABSTRACT
The standard fermentor has been and is the workhorse of the bioreactor stable used in biotechnology. The effects of hydrodynamic forces on animal cells in a stirred bioreactor have been most extensively studied in microcarrier systems, where the cells grow attached to the surface of spherical particles typically about 180 µm in diameter. Insect cells and animal cells can be grown well in large vessels. The Kolmogorov theory and the hypothetical killing volume model are, in this respect, the promising approaches for optimal design of large-scale animal cell bioreactors. In addition, sparged gas bubbles subject the cell to surface tension forces and to fluid mechanical forces resulting from the motion, disengagement and bursting of bubbles, and from foaming. Animal cells on microcarriers are especially susceptible to shear. In addition to the lack of a protective cell wall and their relatively large size, they also lack individual cell mobility.
