Lipids detection and quantification in oleaginous microorganisms: an overview of the current state of the art

Abstract

Oleaginous microorganisms are among the most promising feedstocks for the production of lipids for biofuels and oleochemicals. Lipids are synthesized in intracellular compartments in the form of lipid droplets. Therefore, their qualitative and quantitative analysis requires an initial pretreatment step that allows their extraction. Lipid extraction techniques vary with the type of microorganism but, in general, the presence of an outer membrane or cell wall limits their recovery. This review discusses the various types of oleaginous microorganisms, their lipid accumulating capabilities, lipid extraction techniques, and the pretreatment of cellular biomass for enhanced lipid recovery. Conventional methods for lipid quantification include gravimetric and chromatographic approaches; whereas nonconventional methods are based on infrared, Raman, nuclear magnetic resonance, and fluorescence spectroscopic analysis. Recent advances in these methods, their limitations, and fields of application are discussed, with the aim of providing a guide for selecting the best method or combination of methods for lipid quantification.

Metabolite Quantification by Fourier Transform Infrared Spectroscopy in Diatoms: Proof of Concept on Phaeodactylum tricornutum

“…Scarsini (2021) showed how in N-starvation, cells are principally accumulating neutral lipids through membrane lipid remodeling. The comparison of lipid content estimation through vibrational spectroscopy and a total lipids quantification through another biochemical technique, such as gravimetric analyses ( Patel et al, 2019 ) could potentially reveal a direct linear correlation. The fatty acids measurements (2,855–2,954 cm – 1 ) do not show high correlations, especially when the normalization correction is applied (R 2 <0.43 and r<0.68), probably due to the partial overlapping of these peaks with the large water peak at 3,000–3,700 cm – 1 .…”

MBLDP-R: A Multiple Biomolecules Based Rapid Life Detection Protocol Embedded in a Rover Scientific Subsystem for Soil Sample Analysis

“…Thus, the complexity level of these methods is not suitable for the rover system and it is not convenient for executing the methods in an external environment. In contrast, colourimetric methods for lipid quantification constitute an attractive choice due to their fast response and simplified sample handling; however, they also usually require other preliminary steps such as cell disruption and lipid extraction 46 that is not convenient based on the compatibility and complexity. Furthermore, other nonconventional spectroscopic methods include infrared spectroscopy, nuclear magnetic resonance spectroscopy, Raman spectroscopy, fluorescence spectroscopy and dielectric spectrometry 46 which involve costly equipment.…”

“…In contrast, colourimetric methods for lipid quantification constitute an attractive choice due to their fast response and simplified sample handling; however, they also usually require other preliminary steps such as cell disruption and lipid extraction 46 that is not convenient based on the compatibility and complexity. Furthermore, other nonconventional spectroscopic methods include infrared spectroscopy, nuclear magnetic resonance spectroscopy, Raman spectroscopy, fluorescence spectroscopy and dielectric spectrometry 46 which involve costly equipment. The above analysis shows that the tests of nucleic acid, pigment and lipid detection do not fulfil the minimum criteria of the requirement analysis.…”

Comparison of Cellular Autofluorescence Patterns of Two Model Microalgae by Flow Cytometry

“…operational and analytical platform for the quantification of various microalgae cell components and related byproducts. To specifically analyze, label and even separate microalgae single cells, numerous high throughput methods with advanced analytical potentials including flow cytometry, electrical flow cytometry, electrical microfluidics chip and fluorescence-activated cell sorting have recently been reported[14,15,19,20]. Among them, flow cytometry allows automatic, low-cost, highspeed and simultaneous analysis of multiple parameters of microalgae cells through qualitative and quantitative measurements of biological and physical characteristics.…”