To develop an easy and rapid method of quantifying lipid contents of marine dinoflagellates, we quantified lipid contents of common dinoflagellate species using a colorimetric method based on the sulpho-phospho-vanillin reaction. In this method, the optical density measured using a spectrophotometer was significantly positively correlated with the known lipid content of a standard oil (Canola oil). When using this method, the lipid content of each of the dinoflagellates Alexandrium minutum, Prorocentrum micans, P. minimum, and Lingulodinium polyedrum was also significantly positively correlated with the optical density and equivalent intensity of color. Thus, when comparing the color intensity or the optical density of a sample of a microalgal species with known color intensities or optical density, the lipid content of the target species could be rapidly quantified. Furthermore, the results of the sensitivity tests showed that only 1-3 × 10 5 cells of P. minimum and A. minutum, 10 4 cells of P. micans, and 10 3 cells of L. polyedrum (approximately 1-5 mL of dense cultures) were needed to determine the lipid content per cell. When the lipid content per cell of 9 dinoflagellates, a diatom, and a chlorophyte was analyzed using this method, the lipid content per cell of these microalgae, with the exception of the diatom, were significantly positively correlated with cell size, however, volume specific lipid content per cell was negatively correlated with cell size. Thus, this sulpho-phospho-vanillin method is an easy and rapid method of quantifying the lipid content of autotrophic, mixotrophic, and heterotrophic dinoflagellate species.Key Words: cell size; intensity of color; lipid amount; lipid content per cell; sulfo-phospho-vanilin (SPV); volume specific lipid content
INTRODUCTIONKnowing the lipid content of marine microalgae is important for understanding their metabolism and for the use of their biomass as biofuel. Among them, dinoflagellates contain large amounts of high-quality lipids and dinosterols (Piretti et al. 1997, Mansour et al. 1999.Dinoflagellates play diverse roles in the marine food web as primary producers, prey, predators, symbionts, and parasites (Muscatine 1990, Coats 1999, Jeong et al. 2010, Lee et al. 2014a, 2014b. In the last two decades, many phototrophic dinoflagellates that were previously thought to be exclusively autotrophic have been shown to be mixotrophic (Jacobson and Anderson 1996, Stoecker 1999, Jeong et al. 2005, Lee et al. 2014c. Therefore, these protists not only perform photosynthesis, but also feed on prey as energy sources. Furthermore, many dinoflagellates are important prey for mixotrophic Received October 3, 2016, Accepted December 7, 2016 *Corresponding Author E-mail: bada0@snu.ac.kr Tel: This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original wo...