earticle

영어

Microalgae are photosynthetic microorganisms that can harvest solar energy and convert CO2 and water to organic macromolecules such as carbohydrates, proteins, and lipids. Lipids (especially triacylglycerols) are the main storage compounds in many microalgae, and these could be effectively utilized as a source of biodiesel with dramatically low net carbon emissions than petroleum diesel. Cellular growth and lipid accumulation of microalgae are largely affected by various environmental and nutritional factors including seed condition, kinds and compositions of medium, CO2, pH, light intensity and temperature. Chlorella sp. KR-1 was isolated from thermal power plant and has been reported to have stable growth for high CO2 concentration up to 50%. In this study, before applying KR-1 strain for the production of biodiesel from the flue gas from 2 MW coal-power plant (KIER, Korea), the effects of several cultivation parameters such as inoculum preparation, kinds of medium (namely N-8, BG-11 and KR-1), and nitrate concentration were investigated for its cellular growth and lipid synthesis in flask cultures. The inoculum was cultivated under the same condition of main cultures and transferred at 10% (v/v) with and without centrifugation. Higher specific cell growth rates and cell-densities were observed with centrifugation (4000 rpm, 10 min) irrespective of media used. After 15 day incubation, cell-density with N8 medium was higher than those with KR-1 and BG-11 media when nitrate concentration was fixed at 5 mM. When nitrate concentration was varied in the range of 1 – 30 mM, optimal cell growth (1.0 g/L) was observed at 5 – 10 mM while highest intracellular fatty acids content (348 mg/g cell) was obtained at a low concentration of 1 mM. Maximal fatty acids production obtained under present study was 213 mg/L and major fatty acids were palmitic acid (27%, w/w), oleic acid (23%), and linoleic acid (27%). Other optimization experiments are under progress.