Fig. 6
Quantification of starch, protein and TAG contents via single-cell Raman spectra from wet algal paste and dry algal powder. a Integrity of individual algal cells under the three algal cell-storage conditions of liquid suspension culture, wet algal paste and dry algal powder (Bar = 2 μm). The PLSR models for quantifying starch, protein and TAG contents via SCRS were built for cells in the form of wet algal paste (b) or dry algal powder (c). d Measurements of starch, protein and TAG contents for each of the three algal cell-storage conditions were highly consistent between the conventional method and the SCRS-based approach. PLSR: partial least square regression. TLC–GC–MS: thin-layer chromatography coupled with gas chromatography–mass spectrometry. R 2: correlation coefficient. Larger error bar in TAG measurement might be caused by the relative low level of TAG content in C. reinhardtii cells and the multiple largely manual operations (e.g., lipid extraction and thin-layer chromatography) in determining the TAG content of the cellular biomass