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Absorbance "a tool to measure Growth"

The tool to measure bacterial growth is absorbance (600nm). I am amazed to measure different growth phases of bacterial growth by absorbance.

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Gaurav Gunjal
Project Assistant, Indian Institute of Science, Bangalore, India
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Can anyone tell me what are the components in broth are responsible for absorbance that we measure during bacterial growth. Is it the micro molecules like amino acids (a.a), nucleic acids, vitamins which are absorbing light (knowing that a.a & nucleic acid Abs. max is @ UV) OR as a whole bacterial cell membranes & other components responsible for showing particular absorbance?

Go to the profile of Gaurav Gunjal

Gaurav Gunjal

Project Assistant, Indian Institute of Science, Bangalore, India

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Go to the profile of Andrew Jermy
Andrew Jermy almost 5 years ago

OD600 is primarily a measure of the light scattered by cells in the cuvette rather than absorbance; most bacteria absorb very little light. This link is pretty informative on the theory and measurement of growth in cultures, especially section 4:

http://www.mpi-bremen.de/Binaries/Binary13037/Wachstumsversuch.pdf

Go to the profile of Gaurav Gunjal
Gaurav Gunjal almost 5 years ago

Thanks, the link is informative. Coming back to same minute question with some modification that 'the scattering of light is it due to whole bacterial cell or macromolecules (nucleic acid, amino acid, vitamins) ?