title: Detection of algal lipid accumulation due to nitrogen limitation via dielectric spectroscopy of Chlamydomonas reinhardtii suspensions in a coaxial transmission line sample cell.
abstract: In this study, dielectric characterization of algae cell suspensions was used to detect lipid accumulation due to nitrogen starvation. Wild-type Chlamydomonas reinhardtii (CC-125) was cultivated in replete and nitrogen-limited conditions in order to achieve a range of lipid contents, as confirmed by Nile Red fluorescence measurements. A vector network analyzer was used to measure the dielectric scattering parameters of a coaxial region of concentrated cell suspension. The critical frequency fc of the normalized transmission coefficient |S21(*)| decreased with increasing lipid content but did not change with cell concentration. These observations were consistent with a decrease in cytoplasmic conductivity due to lipid accumulation in the preliminary transmission line model. This dielectric sensitivity to lipid content will facilitate the development of a rapid, noninvasive method for algal lipid measurement that could be implemented in industrial settings without the need for specialized staff and analytical facilities.
authors.affiliation: Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Bono
authors.forename: Beth A
authors.initials: BA
authors.lastname: Ahner
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Kirby
mesh_terms: D016825:Chlamydomonas reinhardtii / Q000378:metabolism*; D050356:Lipid Metabolism; D008962:Models, Theoretical; D009584:Nitrogen / Q000378:metabolism*; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D009584:Nitrogen
keywords: Biodiesel; Biofuel; Lipid measurement; Microalgae; Nutrient limitation