biomass production can be determined/expressed as:

1) absorbance (optical density) at a certain wavelength

2) biomass concentration (dry weight, g/L)

3) cells counting using a hemocytometer (cell/mL)

I think that in this case volumetric productivity (g/L/d or g/L/h) is more recommended.

Thank's for your answers. I study the effect of temperature variation on growth of microalgae. So, I calculated the specific growth rate ( µ, day-1 ) of cells on each growth temperature, which was different (as expected) with variation of growth temperature of culture. But I found the biomass production (g/L) unchanged (constant) for the three different temperature used in my experiment. my question: is it correct if we found variation only on growth rate, but not on biomass production ?

Yes, the biomass achieved (g/L) depends of the nutrients concentration (chemical stoichiometry), of course under optimal growth conditions. Moreover, parameters that relate growth to time (k, yield ...) they "measure" factors such as temperature.

Thanks again for your help. If you have a link of book or paper explaining more about this information. I will be grateful, if you share it with me.

Hello, Rebiha Adjout

Yes, if you have the information of biomass concentration in g/L, you can easily find the specific growth rate from the following formula:

Specific growth rate = (Ln(X2) - Ln (X1))/ (t2 - t1)

in which the X2 and X1 are the biomass concentration at time t2 and t1, respectively.

I hope this was helpful to you.