In the laboratory, at least, one can culture cells in an unrestricted fashion for a number of generations, after which time the cells are considered to be in balanced growth , i.e., they double not only their numbers but their macromolecular constituents at the same rate each generation. By taking a single measurement, the absolute rate of synthesis of a component can also be calculated. Balanced growth is a very reproducible state to achieve, therefore different laboratories can compare their data. In practice, however, we ideally want to use techniques for sampling growth that are accurate, cheap, rapid, and convenient. Based on the assumption that each bacterium in a suspension is capable of forming a single colony.
Bacteria pass through a small orifice and their passage is monitored by a voltage change.
Fast and accurate, but expensive and not widely available. Dry weight measurement. Turbidometric measurements . May be impractical if the medium itself is cloudy or contains materials which absorb strongly in the wavelength range used. Above this value, the culture must be accurately diluted for linearity to be maintained.