Evaluation of methods to extract and quantify lipids from Synechocystis PCC 6803

• Published in: Bioresource technology Vol. 102; no. 2; pp. 1697 - 1703
• Main Authors: Sheng, Jie, Vannela, Raveender, Rittmann, Bruce E.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 2011; [New York, NY]: Elsevier Ltd; Elsevier
• Subjects: Algae; Biodiesel; Biofuel production; Biological and medical sciences; Biomass; Biotechnology; Biotechnology - methods; Chloroform; Chromatography, Gas; Chromatography, Thin Layer; Cyanobacteria; Diglycerides - analysis; Energy; Esters - analysis; Ethyl alcohol; Extraction; Fatty Acids - analysis; Feedstock; Fundamental and applied biological sciences. Psychology; Industrial applications and implications. Economical aspects; Lipid extraction; Lipids; Lipids - analysis; Lipids - isolation & purification; Methyl alcohol; Solubility; Solvents; Solvents - chemistry; Synechocystis; Synechocystis - metabolism; Synechocystis - ultrastructure; Triglycerides - analysis; Lipid extraction; Synechocystis; Biodiesel; Cyanobacteria; Methodology; Bacteria; Lipids
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2010.08.007

In order to use the photosynthetic cyanobacterium Synechocystis as a source of feedstock for carbon–neutral, nonpetroleum-based diesel fuel, we evaluated several solvents and solvent systems for their ability to extract lipid from wild-type Synechocystis PCC 6803. Chloroform + methanol-based Folch and Bligh & Dyer methods had the highest lipid recoveries. Less toxic solvents, such as methanol and MTBE, or direct trans-esterification of biomass (without pre-extraction step) gave only slightly lower lipid-extraction yields. Ethanol, isopropanol, butanol, hexane, acetic ester, and their combinations were not effective for lipid extraction from Synechocystis (>20% loss), even though they are widely used for non-polar lipid extraction from other feedstock, including algae. We confirmed the success of chloroform + methanol-based extraction by their penetration of the cell membrane system, higher polarity, and stronger interaction with hydrogen bonds. The less-polar solvents not only had lower lipid yield, but also extracted more non-lipid compounds that require extra purification to remove. We also characterized the fatty-acid profile of Synechocystis PCC 6803: C16:0 (∼60%), C16:1 (∼9.5%), C18:0 (∼1.2%), C18:1 (∼2%), C18:2 (∼9.8%), and C18:3 (∼16.5%).