Understanding the Bacterial Growth Curve - Foundation Figure 6.15
Bacteria reproduce by a process called binary fission. The length of time it takes for a cell to complete binary fission and form two cells is the generation time. Generation time can also be defined as the length of time required for a population to double.
When a liquid growth medium is inoculated with a few bacteria, the population can be counted at regular intervals, and the counts (logarithm of the number of bacteria) can be plotted over a length of time. In this way, we can develop a visual representation of growth, known as a bacterial growth curve. A typical bacterial growth curve shows four distinct phases: lag phase, log phase, stationary phase, and death phase. Bacterial growth cannot be sustained in this closed system because nutrients become depleted and waste products accumulate, inhibiting further growth. There are open systems, known as chemostats, that can provide a continuous supply of nutrients as well as remove older cells and waste products. Chemostats can sustain bacterial growth indefinitely as long as nutrients are provided and wastes and cells are removed.
Labeling the Phases of a Bacterial Growth Curve
Bacterial growth curves typically can be divided into four distinct phases: lag phase, log phase, stationary phase, and death phase.
Drag the following descriptions to the appropriate location on the bacterial growth curve.