Article: Bono MS, Ahner BA, Kirby BJ, (2013) Detection of Algal Lipid Accumulation Due to Nitrogen Limitation via Dielectric Spectroscopy of Chlamydomanas Reinhardtii Suspensions in a Coaxial Transmission Line Sample Cell. Biosource Technology, 143: 623-631
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 f(c) of the normalized transmission coefficient vertical bar S*(21)vertical bar 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. (c) 2013 Elsevier Ltd. All rights reserved.