Bioreactor
Overview about Stirred Bioreactors
Time：2018.03.16
Stirred reactors rely on stirring paddles to provide power for liquid phase stirring. They have a large operating range, good mixing and uniformity of concentration, and are therefore widely used in biological reactions. However, since animal cells have no cell wall protection, they are very sensitive to shearing action, and direct mechanical agitation can easily damage them. The traditional stirred reactor used for microorganisms is obviously not suitable for the cultivation of animal cells. Therefore, the stirred reactors in animal cell culture have all been improved, including the improvement of the oxygen supply mode, the form of the stirring paddles, and the addition of accessories in the reactor, etc.
(1) Improvement of oxygen supply
In general, stirred reactors are often accompanied by bubbling, which provides oxygen for cell growth. Because animal cells provide required oxygen for the bubbling shear cell growth and because animal cells are also very sensitive to the shear of the bubbling, therefore much work has been done to improve oxygen supply. Cage oxygen is a type of oxygen supply modes for stirred animal cell reactors, namely, the bubbles are separated by mesh and are not in direct contact with the cells. The reactor can not only ensure the mixing effect but also have as little shear force as possible to meet the requirements of cell growth. Kitano Shoichi reported on an improved stirred animal cell reactor that was pear-shaped as a whole, stirred on the bottom of the reactor, a cone-shaped stainless steel wire mesh is mounted outside the agitator shaft to rotate with the agitator shaft. The bubbling tube at the axial center is bubbled inside the screen, and the cells outside the screen are not in direct contact with the air bubbles.
(2) Improvement of stirring paddles
The form of the stirring paddle has a great influence on the cell growth. The improvement in this aspect mainly considers how to reduce the shear force applied to the cells. Some people have improved the form of the stirring paddle and added auxiliary parts in the reactor. The experiments show that the improved reactor is suitable for high-density culture of cells with sensitive shear force.
(1) Improvement of oxygen supply
In general, stirred reactors are often accompanied by bubbling, which provides oxygen for cell growth. Because animal cells provide required oxygen for the bubbling shear cell growth and because animal cells are also very sensitive to the shear of the bubbling, therefore much work has been done to improve oxygen supply. Cage oxygen is a type of oxygen supply modes for stirred animal cell reactors, namely, the bubbles are separated by mesh and are not in direct contact with the cells. The reactor can not only ensure the mixing effect but also have as little shear force as possible to meet the requirements of cell growth. Kitano Shoichi reported on an improved stirred animal cell reactor that was pear-shaped as a whole, stirred on the bottom of the reactor, a cone-shaped stainless steel wire mesh is mounted outside the agitator shaft to rotate with the agitator shaft. The bubbling tube at the axial center is bubbled inside the screen, and the cells outside the screen are not in direct contact with the air bubbles.
(2) Improvement of stirring paddles
The form of the stirring paddle has a great influence on the cell growth. The improvement in this aspect mainly considers how to reduce the shear force applied to the cells. Some people have improved the form of the stirring paddle and added auxiliary parts in the reactor. The experiments show that the improved reactor is suitable for high-density culture of cells with sensitive shear force.