ABSTRACT
Multi-stage complex systems might be therefore advantageous and optimal for most microbial processes and giving the lowest total holding time needed to achieve a desired stage of conversion. The increase of cell mass, i.e., the growth rate, is a complex function of many variables and can be considered as an indicator of the physiological state of the culture of microorganisms. Complex systems may reveal their advantages when the substrate, even a multiple one in a complex medium, is to be effectively consumed or when it is necessary to cultivate cells in a particular physiological state, i.e., cells having a particular quality and ability to produce a product of interest. Issuing from the knowledge of the process some regulatory mechanisms can be eliminated, and models less complex may be obtained. A dialysis culture of microorganisms can also be classified as a complex system.
