Microalgae triacylglycerols content by FT-IR spectroscopy

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Microalgae triacylglycerols content by FT-IR spectroscopy Roberta Miglio & Stefano Palmery & Mario Salvalaggio & Lino Carnelli & Federico Capuano & Raffaella Borrelli

Received: 30 August 2012 / Revised and accepted: 13 February 2013 / Published online: 20 March 2013 # Springer Science+Business Media Dordrecht 2013

Abstract The present study aims to develop a methodology via Fourier transform infrared (FT-IR) spectroscopy for the semiquantitative determination of triacylglycerols (TAGs) in microalgal consortia, consistent with the use of the technique as process control. FT-IR spectroscopy has proved to be a powerful analytical tool for the identification of macromolecular pools (e.g., proteins, lipids, and carbohydrates) and in monitoring biochemical changes (including lipids) in response to nutrient stress or environmental modifications. In the Oocystis-based consortium under examination, the synthesis of neutral lipid in the form of TAGs can be induced, applying stress condition, and these lipids are suitable as biodiesel precursors. In the exponential growing phase, the consortium shows a low TAGs content, in the order of 5 %w, that can be increased till around 22 %w on ash free dry matter, after nitrogen starvation. Keywords Microalga . Starvation . FT-IR . Triacylglycerol . Lipid

Introduction Recent reports on next-generation biofuels produced via biomass are showing significant improvements on greenhouse gases emission savings, carbon footprint, and environmental sustainability with respect to first-generation biofuels. In the group of biomasses, phototrophic algae are R. Miglio (*) : S. Palmery : M. Salvalaggio : L. Carnelli : R. Borrelli ENI–Research Center for Non Conventional Energies, via Fauser, 4 28100 Novara, Italy e-mail: [email protected] F. Capuano ENI–Refining & Marketing Division, via Laurentina 441, Rome, Italy

extremely promising, also for their ability to mitigate aquatic pollution and to sequester CO2 from power plants. In the photosynthetic pathway, algae are able to produce lipids, in the order of 10–60 % by weight, and other compounds like proteins and polysaccharides, which are reconverted among each others during different growing phases (Richardson et al. 1969). An important challenge for algal-derived biofuels is the utilization of open ponds (OPs) for large-scale cultivation. The environmental in and around OPs cannot be completely controlled and a number of factors can interfere with the growing phases and can influence productivity and biomass quality (consortium population). A key factor for microalgae in the energy market is the lipid content (Griffiths and Harrison 2009), which must be maximized and preferentially routed to high content of triacylglycerols (TAGs). An accurate method for lipid quantification in algal biomass is necessary for the purpose of identifying optimum species and growth conditions. Moreover, the availability of efficient and rapid analytical techniques, providing biomass and lipid screening, is essential as process control on large scale and could b