Lipid quantification techniques for screening oleaginous species of microalgae for biofuel production

Abstract

This review examines the available literature on quantifying lipids in microalgae suitable for biofuels research. It discusses their advantages and disadvantages, their prevalence in the literature, and draws conclusions about the best way to approach choosing a suitable lipid measurement technique for microalgal biofuels research. We conclude that the method must be chosen based on the following key criteria: (1) the level of detail required in the results, and (2) the amount of biomass that can be spared for the assay. This review establishes that no method can be used as a “golden standard” for all microalgae. However, we present a systematic decision chart to choose the best measurement method or combination of methods to provide a guide to those wishing to understand the differences between the myriad of lipid measurement techniques.Practical applications: This review will allow researchers new to the field to choose the most appropriate techniques for quantifying lipids in the microalgal species under study. The review is also intended to act as a gateway to the wider literature and will enable researchers to look in depth at a particular technique before carrying out experimental work.These two figures show contrasting results obtained from one set of samples using esterification with GC (left hand figure), and Nile Red staining with fluorescence measurement (right hand figure). The Nile Red method indicates a high accumulation of lipids over time in 0.3 M NaCl, whereas the GC method indicates the opposite pattern of decreasing FAME content over time in the high salt conditions (green line in each figure). The contrasting results highlight the problem of accuracy in lipid measurement, and how it is possible to be misled if only one experimental technique is used.