Bacterial generation time. Introduction Bacterial population can be estimated by measuring the optical density or turbidity of a suspension. When several measurements are made over time, the growth rate of the bacteria can be calculated.
Optical density is directly proportional to the number of cells.
When the bacterial population doubles, the optical density of the bacterial suspension also doubles. The average time required for one bacterium to divide under optimum conditions is called the generation time. In this experiment, students will measure optical density with a spectrophotometer. As the number of cells within a given volume increases, the amount of light transmitted through the sample decreases. Therefore, light absorption is positively correlated with cell concentration.