Bioreactors are considered 3D-culturing vessels with process controls to achieve an optimum environment for cell growth, and higher volumetric productivity than using 2D-culturing vessels.

In 2D culture model, cells grow attached to a 2-dimensional surface. In 3D culture model, cells grow in suspension in the bulk liquid. Culture vessel design is critical in Upstream Bioprocess Engineering because growing cells is central to Upstream Bioprocesses.

Mixing is critical in 3D culturing vessels because it ensures uniform nutrient distribution, minimizes waste accumulation, prevents cells from settling, and maintains homogeneous environmental conditions across the vessel.

The 4 main modes of bioreactor operation have different PROS and CONS. Thus, selection of the mode of operation is critical for the desired production end goal and biomanufacturing design process constraints.