NMR-based Metabolomics of Cellular and Developmental Changes in Lipogenic Algae

As the need for development of feasible alternative energy sources increases, understanding oil production in algae has become imperative. Our lab found that as cultures of the green algae Dunaliela primolecta develop, changes are observed in cell morphology (cell shape and size) and biochemistry (chlorophyll and neutral lipid content). Furthermore, it was observed that algal cells show similar developmental discrepancies when grown in different types of media. We therefore wanted to determine if these observed changes could be analyzed and quantified at the metabolic level using NMR spectroscopy. This method could be used to evaluate the efficacy of growth media and other precursors in promoting lipogenesis in algae.

Growth curves of D. primolecta were generated by measuring the increase in cell density every 24 hours. Based on those data, a sampling procedure was established to harvest algae cells at three landmarks in the logarithmic growth curve—designated as T1, T2, and T3. Cells were harvested at these time points and metabolites were extracted using Methanol D4. 1H NMR spectra were acquired using a Varian 400MHz spectrometer.

Analysis of spectra obtained from D. primolecta at different time points yielded significantly different spectra (particularly in the 1-4ppm region) between early-growth stage (T1) and late-growth stage (T2-T3) cultures, coincident with changes in bulk cell morphology. The next step in this project would involve testing the changes in algae cells grown in different media—the results of such an experiment would be very informative as to how media influence algal lipogenesis.