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.
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Turbidity is commonly measured using a spectrophotometer, which quantifies the degree to which particles in a sample scatter light.
High turbidity in a microbial culture usually indicates high cell density.
Turbidity measurements are non-destructive and allow for continuous monitoring of microbial growth without sampling the culture.
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.
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.