The effects of nitrogen sources and temperature on cell growth and lipid accumulation of microalgae

Microalgal lipids are potential sustainable biodiesel feedstocks in the future. In this study, effects of temperature, nitrogen sources and potassium ion on cell growth and lipid accumulation of Monoraphidium sp. SB2 isolated from Taiwan ponds and the cultivation in industrial wastewater were studied. The results indicated that the biomass obtained with potassium nitrate as nitrogen source was higher than with other nitrogen sources (ammonium chloride and ammonium nitrate). Potassium ion stimulated the uptake of ammonium in the artificial medium. Monoraphidium sp. SB2 could grow well under 25-35 °C but decay at 40 °C. The highest microalgal lipid content (32.9%) was obtained at 25 °C, but the highest biomass concentration (650 mg l−1) and lipid productivity (29.2 mg l-1 d-1) was achieved at 30 °C. Cultured in industrial wastewater, Monoraphidium sp. SB2 can also produce 34.7% of lipid content. Monoraphidium sp. SB2 is a promising microalgal strain for biodiesel production because of its ability to grow in industrial wastewater.