Monday, June 21, 2010

Biofuels – The Importance of Algae

Diminishing stocks of fossil fuels along with the increasing emission of greenhouse gases such as carbon dioxide as a result of fossil fuel combustion has driven the research on alternative and renewable fuel sources such as biomass-derived fuels. Microalgae represent a potential source of biomass fuel production. Microalgae is a generic term describing small prokaryotic (cyanobacteria) and eukaryotic organisms found in most freshwater and marine systems that use sunlight to fix carbon by making sugars from CO2 and water.

Unlike grain based ethanol production algal fuel production does not compete directly with food stocks, making their use more palatable. Many microalgae have the ability to produce large amounts of triacylglycerols (TAG) as a storage lipid under certain stress conditions. Unlike terrestrial plants, microalgae do not require fertile land or irrigation. Because algae consume carbon dioxide, large scale cultivation can be used to remediate the combustion exhaust of power plants. Unfortunately most of the cultured strains of photo-synthetic micro-organisms used in the laboratory were selected for their ease of cultivation or as genetic modeling systems rather than their ability to produce biofuel compounds [1].

Recent work has focused on improving lipid content of algae by identifying improved growth media, isolation of specific over-producing strains or through the use of genetic modification of microalgal metabolic enzymes [2]. Because of the large number of growth variables including light intensity, ionic strength, dark cycle length, pH, temperature, culture dish geometry, CO2 concentration, mixing, nitrogen and phosphate concentrations, water purity, media feedstock, etc., fractional factorial experimental designs [3] are often used to measure many factors in a manageable number of experimental runs. Microplates (96‐ and 384-well) make perfect culturing vehicles for assessing growth and/or TAG production from algal cultures under these numerous experimental conditions. The multimode readers from BioTek, such as the Synergy H4, Synergy 2, and Synergy Mx are ideal reader platforms for quantitation of these metrics and the many others associated with biofuel production.

References

1. Hu, Q., M. Sommerfield, E. Jarvis, M. Ghirardi, M. Posewitz, M. Seibert, and A. Darzins (2008) Microaggal triacylglycerols as feedstocks for biofuel production: perspectives and advances. The Plant Journal 54:621-639.

2. Rosenberg, J.N., G.A. Oyler, L. Wilkinson, and M.J. Betenbaugh (2008) A green light for engineered algae: redirecting metabolism to fuel a biotechnology revolution. Curr. Opin. In Biotechnology. 19:430-436.

3. Montgomery, D.C. (2001) Design and Analysis of Experiments, 5th ed. Wiley

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