Simultaneous Quantification of Cellular Lipids and Carotenoids Inside Chlorella Vulgaris Using Raman Spectrometry

AbstractA rapid quantification method for lipids and carotenoids in Chlorella vulgaris is demonstrated in this study. The rapid quantification translates Raman signal intensities into abundances of lipids and carotenoids via calibration curves established by gravimetric method (lipids) and UV spectrometry (carotenoids). The Raman signal intensities and the measured amounts of lipids and carotenoids are highly correlated with R2 higher than 0.94. The quantification method is further applied to monitor the actual process of microalgae cultivation. When monitoring the culture of Chlorella vulgaris, we found that the ratio of signals from carotenoids and lipids can change as much as 75% in 1 day when nutrient depletion was induced. Since the signal of total lipids remains relatively stable after the carbon source is depleted, degradation of carotenoids is responsible for the shifting of signal ratio. These results demonstrate the possibility of using Raman spectrometry for rapid quantification of multiple cellular contents and the obtained information is highly valuable for improving cultivation strategies and screening of cells producing valuable products