What is a turbidostat?

A turbidostat is a device that maintains a constant cell density in bacterial cultures by continuously monitoring and adjusting the culture conditions.

How does the turbidostat measure bacterial concentration?

It uses a laser diode to measure optical density, which correlates with bacterial concentration based on light scattering.

What are the benefits of using a turbidostat?

It allows for real-time monitoring and adjustments, ensuring consistent culture conditions and accurate experimental results.

What role does the mathematical algorithm play in the turbidostat?

The algorithm analyzes optical data to estimate bacterial growth rates and determine when to adjust the culture conditions.

Can the turbidostat be used for other types of cells?

While primarily used for bacteria, the principles of a turbidostat can be adapted for other cell types with appropriate modifications.

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

JoVE Encyclopedia of Experiments

Microbiology

0 views • 1:22 min • October 30th, 2025

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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.