Effects of nitrogen sources on cell growth and lipid accumulation of green alga Neochloris oleoabundans

• Published in: Applied microbiology and biotechnology 2008-12, Vol.81 (4), p.629-636
• Main Authors: Li, Yanqun, Horsman, Mark, Wang, Bei, Wu, Nan, Lan, Christopher Q
• Format: Article
• Language: English
• Subjects: Algae; Aquatic plants; biodiesel; Biodiesel fuels; Biofuel; Biofuel production; Biofuels; Biological and medical sciences; Biomass; Biotechnological Products and Process Engineering; Biotechnology; Cell growth; Cellular biology; Chlorophyll; Chlorophyll - metabolism; Chlorophyta - growth & development; Chlorophyta - metabolism; Energy; Fatty acids; Fundamental and applied biological sciences. Psychology; Industrial applications and implications. Economical aspects; Life Sciences; Lipid Metabolism; Lipids; Microalgae; Microalgal oils; Microbial Genetics and Genomics; Microbiology; Neochloris oleoabundans; Nitrates; Nitrogen; Nitrogen - metabolism; Nitrogen sources; Nitrogen-starvation; Production costs; Productivity; Sodium; Studies; Sustainable production; Triglycerides
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-008-1681-1

Microalgal lipids are the oils of future for sustainable biodiesel production. However, relatively high production costs due to low lipid productivity have been one of the major obstacles impeding their commercial production. We studied the effects of nitrogen sources and their concentrations on cell growth and lipid accumulation of Neochloris oleoabundans, one of the most promising oil-rich microalgal species. While the highest lipid cell content of 0.40 g/g was obtained at the lowest sodium nitrate concentration (3 mM), a remarkable lipid productivity of 0.133 g l⁻¹ day⁻¹ was achieved at 5 mM with a lipid cell content of 0.34 g/g and a biomass productivity of 0.40 g l⁻¹ day⁻¹. The highest biomass productivity was obtained at 10 mM sodium nitrate, with a biomass concentration of 3.2 g/l and a biomass productivity of 0.63 g l⁻¹ day⁻¹. It was observed that cell growth continued after the exhaustion of external nitrogen pool, hypothetically supported by the consumption of intracellular nitrogen pools such as chlorophyll molecules. The relationship among nitrate depletion, cell growth, lipid cell content, and cell chlorophyll content are discussed.