Continuous Culture of Bacteria at Constant Density via Automated Growth Rate Estimation

Begin with a turbidostat, a device that maintains a constant cell density in culture.

The device contains a vessel with a bacterial culture, which is continuously aerated by stirring and maintained at a constant temperature.

A laser diode emits a light beam that is split into two paths.

One path is directed to a reference sensor to monitor laser intensity fluctuations, while the other passes through the culture.

Bacterial cells scatter and absorb light, decreasing the transmitted intensity, which is detected by a second sensor.

This reduction in intensity reflects the bacterial concentration and is measured as optical density (OD).

When the OD rises above the target threshold, a pump adds fresh medium to dilute the culture.

Simultaneously, an air pump removes excess medium through the effluent tube, maintaining a constant volume.

A mathematical algorithm continuously analyzes the optical data to estimate bacterial growth rates.