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Optical density

Definition

noun

(1) The measure of transmittance of an optical medium for a given wavelength. The higher the OD the lower the transmittance, the higher protection factor by a filter (e.g. goggles, viewing windows, etc.).

(2) The measure of the amount of light absorbed by a suspension of bacterial cells or a solution of an organic molecule with the use of a colourimeter or spectrophotometer.


Supplement

In microbiology, the values can be used to measure turbidity, which in turn is used to estimate the number of bacteria (or concentration of molecules like proteins) in a solution.


Abbreviation: OD

Synonym: absorbance.
See also: absorption.


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Results from our forum


Problem with Lab result

... you dilute your sample, you have less bacteria per volume and thus the optical density decreases.

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by JackBean
Sat Feb 18, 2012 9:26 am
 
Forum: Microbiology
Topic: Problem with Lab result
Replies: 2
Views: 1769

Problem with Lab result

... the undiluted culture?___I didn't get this answer :oops: Second Part: Optical density determination Dilution --- Optical Density 1:1 --- 30% T; 0.56 A 1:2 --- 50% T ; 0.33 ...

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by Layd33foxx
Sat Feb 18, 2012 5:33 am
 
Forum: Microbiology
Topic: Problem with Lab result
Replies: 2
Views: 1769

Incubation of Soil Fungi

... of grown colonies. To make it easier later, measure also OD600 (the optical density at 600 nm) and make some correlation graph.

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by JackBean
Thu Nov 03, 2011 9:23 am
 
Forum: Microbiology
Topic: Incubation of Soil Fungi
Replies: 4
Views: 3089

E.coli cell counting by OD

... some stuff on google, if you type in "e coli cell counting using optical density" then the third hit down "Laboratory 6" gives you the background and ...

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by Kezzer
Wed Dec 22, 2010 9:03 am
 
Forum: Microbiology
Topic: E.coli cell counting by OD
Replies: 1
Views: 1690

Measuring OD

... first, but I think, it should be OK (although you will have smaller optical density!).

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by JackBean
Fri Dec 10, 2010 6:40 am
 
Forum: Cell Biology
Topic: Measuring OD
Replies: 5
Views: 4503
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