Chapter 3 Thermodynamics
of Cellular Growth
Microbial growth consists of a complex network of metabolic reactions. Coupled catabolic and anabolic reactions take place so that energy released in the former is efficiently used to drive the latter. However, some energy is always lost as heat. The purpose of this chapter is to quantify the heat release due to growth. In large-scale processes it is necessary to remove this heat so that the culture is maintained at physiological temperature. In small reactors metabolic heat is removed quite easily, while in very large fermentors ( >10,000 liters) in which rapidly growing cells are cultivated, it is necessary to design adequate heat transfer area for heat removal. Bioreactor temperatures must be maintained within ± 0.5 C to maintain physiologic conditions conducive to optimal growth.