title: Microplate assay for quantitation of neutral lipids in extracts from microalgae.
abstract: Lipid quantitation is widespread in the algae literature, but popular methods such as gravimetry, gas chromatography and mass spectrometry (GC-MS), and Nile red cell staining suffer drawbacks, including poor quantitation of neutral lipids, expensive equipment, and variable results among algae species, respectively. A high-throughput microplate assay was developed that uses Nile red dye to quantify neutral lipids that have been extracted from algae cells. Because the algal extracts contained pigments that quenched Nile red fluorescence, a mild bleach solution was used to destroy pigments, resulting in a nearly linear response for lipid quantities in the range of 0.75 to 40 μg. Corn oil was used as a standard for quantitation, although other vegetable oils displayed a similar response. The assay was tested on lipids extracted from three species of Chlorella and resulted in close agreement with triacylglycerol (TAG) levels determined by thin layer chromatography. The assay was found to more accurately measure algal lipids conducive to biodiesel production and nutrition applications than the widely used gravimetric assay. Assay response was also consistent among different species, in contrast to Nile red cell staining procedures.
authors.affiliation: Department of Biological and Agricultural Engineering, University of California, Davis, Davis, CA 95616, USA.
authors.forename: Brendan T
authors.initials: BT
authors.lastname: Higgins
authors.affiliation: Department of Biological and Agricultural Engineering, University of California, Davis, Davis, CA 95616, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Thornton-Dunwoody
authors.affiliation: Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Labavitch
authors.affiliation: Department of Biological and Agricultural Engineering, University of California, Davis, Davis, CA 95616, USA. Electronic address: jsvander@ucdavis.edu.
authors.forename: Jean S
authors.initials: JS
authors.lastname: VanderGheynst
mesh_terms: D056804:Biofuels; D002708:Chlorella / Q000737:chemistry*; D008055:Lipids / Q000032:analysis*; D010936:Plant Extracts / Q000737:chemistry*
chemical_list: D056804:Biofuels; D008055:Lipids; D010936:Plant Extracts
keywords: Chlorella spp.; GC–MS; Gravimetric; Neutral lipid assay; Nile red; TLC