Improving the reliability of fluorescence-based neutral lipid content measurements in microalgal cultures

• Published in: Algal research (Amsterdam) 2012-10, Vol.1 (2), p.176-184
• Main Authors: De la Hoz Siegler, H., Ayidzoe, W., Ben-Zvi, A., Burrell, R.E., McCaffrey, W.C.
• Format: Article
• Language: English
• Subjects: BODIPY; Chlorophyceae; Fluorescence; High-throughput; Microalgae; Nile Red; Trebouxiophyceae
• ISSN: 2211-9264; 2211-9264
• DOI: 10.1016/j.algal.2012.07.004

Fast and accurate determination of lipid content in microalgal cultures is a required step for algal bioprocess development and optimization. An improved high-throughput Nile Red staining protocol using a microplate fluorescence reader is proposed, resulting in an increased correlation coefficient and a reduction in the relative standard deviation of 84% when compared to previously reported staining protocols. Differences in the staining efficacy of Nile Red among different algal strains were observed, even though the performance of the proposed method was found to be satisfactory for the different Trebouxiophyceae and Chlorophyceae microalgal cultures evaluated. Therefore, the proposed Nile Red method should only be used for evaluating lipid content variations in previously standardized strains. BODIPY 505/515 was evaluated as a potential substitute for Nile Red, but was found to be unsuitable as a quantitative stain for algal lipids in the microplate-based staining technique. ► An optimized Nile-Red fluorometric method with reduced variability is proposed. ► The microplate-based technique allows fast and reliable neutral lipid quantitation. ► Confidence in the use of Nile Red as a quantitative staining agent is improved. ► Proposed method can be used for culture monitoring and process condition screening. ► BODIPY was unsuitable for quantifying oil content in the microplate-based technique.