Study on the Relationships between Optical Density at Certain Wavelength and Cell Dry Weight and Cell Concentration of Three Microalgae

[Objective] The aim of the study was to measure the biomass of the three microalgae easily and realize the conversion between optical densities(ODs),cell dry weights and cell concentrations of the three microalgae.[Method] The OD values of three microalgae(Chlorella pyrenoidosa at 680 nm,Dunaliella salina at 630 nm and Spirulina platensis at 560 nm) and their cell dry weights,cell concentrations were tested respectively and the relationships were studied by means of the linear fitting.[Result] The OD,cell dry weights and cell concentrations of three microalgae were in good linear relationships except that of Spirulina Platensis.The linear functions were as follows:cell concentration of Chlorella pyrenoidosa(×104/ml)=1 557 OD680-34.716,cell dry weight of C.pyrenoidosa(mg/ml)=0.207 4 OD680+0.002 2;cell concentration of Dunaliella salina(×104/ml) =901.98 OD630+5.140 8,cell dry weight of D.salina(mg/ml)=0.751 6 OD630+0.015;cell dry weight of Spirulina platensis(mg/ml) = 0.239 4 OD560-0.000 1.[Conclusion] The three microalgae had good linear relationships between their OD values,cell concentrations and cell dry weights in certain ranges respectively.According to the linear functions,the three indicators of the microalgae biomass could be easily detected and converted,which would be helpful for the measurement and comparison of the the three mciroalgae's biomass.