IGEM:IMPERIAL/2007/Projects/Hrp System/Testing/Absorbance

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The Absorbance of the cultures in the wells are measured to allow to convert our absorbance raw data into a cell count, so that cell we can relate GFP synthesis per cell.

Calibration Curve Principle

Example of Absorbance Calibration Curve
  • Cultures of the E.coli with the relevant vector are grown to various cell densities. A sample of these cultures are taken and a dilution plate is carried out to work out approximate cell densities.
  • These Cultures have their absorbance measured at 600nm to give an absorbance measurement for the various cell densities.
  • This data set is then combined, creating a graph relating the number of colony forming cells per ml to their absorbance measurements.
  • With this information, then the absorbance of each culture in the wells can be measured and converted into an approximation of the colony forming units per ml.
  • The image to the right illustrates the outcome of a absorbance calibration curve.


  • Does this calibration curve need to be performed for each device? The different vectors may have an effect, however this should be minimal. Certainly for different strains new calibration curves are needed.