Raman microspectroscopy of algal lipid bodies: β-carotene quantification

Abstract

Advanced optical instruments can serve for analysis and manipulation of individual living cells and their internal structures. We have used Raman microspectroscopic analysis for assessment of β-carotene concentration in algal lipid bodies (LBs) in vivo. Some algae contain β-carotene in high amounts in their LBs, including strains which are considered useful in biotechnology for lipid and pigment production. We have devised a simple method to measure the concentration of β-carotene in a mixture of algal storage lipids from the ratio of their Raman vibrations. This finding may allow fast acquisition of β-carotene concentration valuable, e.g., for Raman microspectroscopy assisted cell sorting for selection of the overproducing strains. Furthermore, we demonstrate that β-carotene concentration can be proportional to LB volume and light intensity during the cultivation. We combine optical manipulation and analysis on a microfluidic platform in order to achieve fast, effective, and non-invasive sorting based on the spectroscopic features of the individual living cells. The resultant apparatus could find its use in demanding biotechnological applications such as selection of rare natural mutants or artificially modified cells resulting from genetic manipulations.

Monitoring of Microalgal Processes

“…The high spatial resolution of Raman scattering allows the study of the distribution of lipid bodies in the cell and their beta-carotene content [218][219][220] and estimation of the lipid body volume in the cell by the amount of beta-carotene [221]. The degree of unsaturation and transition temperatures of lipids, which are important for the biodiesel quality [222,223] and structural changes of astaxanthin with temperature [224], were investigated using this approach.…”

Concentration of Algal Cells for Raman Analysis by Electrowetting on Dielectrics (EWOD)

“…Identification of algae species [11,12], probing the influence of environment on microalgae [13], quantification of degree of unsaturation [14] and β -carotene [15] in the lipid bodies, etc. have been reported.…”

“…Raman spectroscopy, a powerful tool to determine chemical composition of materials, has been utilized to characterize many biological systems [9]. This is because the Raman signal of water is weak and uncomplicated, the sample can be analyzed in-vivo, and sample preparation is generally not required [10].Identification of algae species [11,12], probing the influence of environment on microalgae [13], quantification of degree of unsaturation [14] and β -carotene [15] in the lipid bodies, etc. have been reported.…”

Generation of Volatile Compounds from Carotenoids ofDunaliella bardawilAlgae by Water Bath Heating and Microwave Irradiation

“…[3][4][5][6][7] The production of microalgae supplies the cosmetic and food supplement industries, and boosts the development of natural food products, an emerging and promising field for industrial application.…”

“…1,2 They produce a great diversity of compounds with high commercial value, such as polyunsaturated fatty acids, carotenoids, phycobilins, polysaccharides, vitamins and sterols. [3][4][5][6][7] The production of microalgae supplies the cosmetic and food supplement industries, and boosts the development of natural food products, an emerging and promising field for industrial application. 8 Microalgae have properties typical of higher plants (efficient oxygenic photosynthesis and simplicity of nutritional requirements), but also biotechnological attributes of microbial cells (rapid growth in culture medium and capacity to accumulate or secrete metabolites of interest), 4 supporting large scale applications.…”