Turbidity

Definition

Turbidity is a measure of the cloudiness or haziness of a fluid caused by large numbers of individual particles. In microbiology, it is often used as an indicator of microbial growth in liquid culture media.

5 Must Know Facts For Your Next Test

1. Turbidity is commonly measured using a spectrophotometer, which quantifies the degree to which particles in a sample scatter light.
2. High turbidity in a microbial culture usually indicates high cell density.
3. Turbidity measurements are non-destructive and allow for continuous monitoring of microbial growth without sampling the culture.
4. The relationship between turbidity and cell concentration can be represented by Beer's Law, up to a certain cell density where linearity no longer holds.
5. Calibration curves are necessary to correlate turbidity readings with actual cell counts.

Review Questions

• How does increased turbidity correlate with microbial growth?
• What instrument is typically used to measure turbidity in a liquid culture?
• Why might Beer's Law become inaccurate at high cell densities?

Related terms

Spectrophotometer: An instrument that measures the amount of light that passes through a sample.

Cell Density: The number of cells per unit volume in a culture.

Beer's Law: A principle stating that absorbance is proportional to concentration up to certain limits.