Figure 1. Growth curve of bacteria in batch culture. The growth phases are explained in the text.

Figure 2. Apparatus for continuous culture of bacteria in a chemostat. Fresh medium is pumped into the culture vessel, and the culture volume in the vessel is kept constant by an overflow. Sterile air may be passed through the culture to support growth of respiring bacteria. Likewise, oxygen-free gas mixtures or molecular nitrogen may be used when culturing bacteria that carry out fermentations.