Chlorella vulgaris is being grown in bold basal's media and i need to check its optical density.
I do not like using OD for algae, but if you need to monitor OD it is best to use 750 nm.
In many other places it is mentioned that it can be done at 680nm any specific reason why at 750nm?
Typically 680nm is associated with chlorophyll absorption and has the possibility of interfering with results. 750 nm is above chlorophyll absorption.
just remember that if you use it instead than cell numbers to detect growth phases, you might end up with a wrong conclusion, since OD tend to increase with the age of culture, independently fron cell division (increase in cell dimensions but nor cell numbers, which might become fairly significant with Chlorellales, release of organic matter and pigments, bacteria growth, among others). Once said this, most OD readings are at 550 nm (minimum chlorophyll adsorpion), although you migh also take Everett's advice or even better, build your own regression line according to your needs.
@Nawar, It may varies species to species. Put a diluted sample in cuvettee in spectrophotometer. There you will find a scan button. scan the sample between 600-800nm range. select the wavelength at which you will get the higest absorption.
I feel that all distinguished colleagues who answered (including myself) failed to ask the basic question: what do you want to measure? Chlorophylls? Biomass? do you simply wish to know if your culture is growing, or do you want to control whether a continuous or semicontinuus culture is performing as expected?
Once you decide what you want to know (and keeping in mind that I fully agree with Everett's opinion on the generally poor information you get out of OD readings), the DIY (do it yorself ) approach is as always the best. Buid your own calibration curve and check periodically that the information you get is dependable.
For cell number and optical density (OD) wavelength at 540nm is suitable for Chlorella vulgaris. I agree with Domenico voltolina suggestion.
If I want to determine biomass at 660nm it's ok for Chlorella spp.?
Thank you
Do you have any literature recommendation, where 750 is used? Thank you.
Julieta Lois-Milevicich, regarding the literature suggesting 750 nm check the following paper
Interference by pigment in the estimation of microalgal biomass concentration by
optical density (Melinda J. Griffiths, Clive Garcin, Robert P. van Hille, Susan T.L. Harrison)
I have pure culture of Acutodesmus obliquus grown in bold basal's media and i need to monitor its growth via optical density.which nm should be appropriate?
@karthika menon. 750nm is better choice for you or else make a calibration curve
The best wavelength for measurement of Chlorella vulgaris optical density (OD)is 540nm.
Algal pigment contents including chlorophyll a and b are frequently changed under different environmental conditions (especially, different light intensities or photoperiods) or supplemented nutrients (especially by organic carbon sources). If you want compare growth conditions with control culture, you should avoid pigment wavelengths (Chl a; 680 nm, Chl b; 650 nm, Carotenoid; 480 nm). But if you just want know daily changes of single Chlorella sp. culture, you can measure at 680, 650 or 480 nm.
What about the Desmodesmus sp. and Acutodesmus sp.? we want to analyze the optical density, biomass anad chl a and total carotenoid daily. which nanometer is the best? and is there any stabil value that indicates the stationary phase?
thank you
All the algae irrespective of their class (green, red, brown or blue green) must be containing chl a whose absorption maxima is 680nm. And UV-Vis spectrometer measures the amount of light transmitted out of 100% after absorption. So as much is number of algal cells, that much will be absorption at 680nm and rest light will be transmitted. Thus, 680nm gives best idea about algae culture's optical density.
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