Chapter 2 Stoichiometry
of Cellular Growth
A good starting point for discussion on cell growth is to examine what the cells are made of, that is its chemical composition. Although there are many different biological species, it turns out that a very large fraction of their mass is made of a few elements - carbon, oxygen, nitrogen and hydrogen. You will note that these are among the most abundantly found elements on earth.
In this chapter we introduced the idea of growth reaction to characterize material balance associated with cell growth. We defined a chemical formula which represents about 95% of the dry matter of biomass. We also defined yield which enables us to derive usful engineering information from literature articles that report cell yield. To carry out material balances around a fermentor requires, in general, respiratory quotient values and one other measurement.