Effects of cultivation conditions and media composition on cell growth and lipid productivity of indigenous microalga Chlorella vulgaris ESP-31

The growth and lipid productivity of an isolated microalga Chlorella vulgaris ESP-31 were investigated under different media and cultivation conditions, including phototrophic growth (NaHCO3 or CO2, with light), heterotrophic growth (glucose, without light), photoheterotrophic growth (glucose, with light) and mixotrophic growth (glucose and CO2, with light). C. vulgaris ESP-31 preferred to grow under phototrophic (CO2), photoheterotrophic and mixotrophic conditions on nitrogen-rich medium (i.e., Basal medium and Modified Bristol’s medium), reaching a biomass concentration of 2–5 g/l. The growth on nitrogen-limiting MBL medium resulted in higher lipid accumulation (20–53%) but slower growth rate. Higher lipid content (40–53%) and higher lipid productivity (67–144 mg/l/d) were obtained under mixotrophic cultivation with all the culture media used. The fatty acid composition of the microalgal lipid comprises over 60–68% of saturated fatty acids (i.e., palmitic acid (C16:0), stearic acid (C18:0)) and monounsaturated acids (i.e., oleic acid (C18:1)). This lipid composition is suitable for biodiesel production.

► Effects of medium and growth conditions on microalgal lipid production were studied.
► Mixotrophic growth was preferable for lipid production of Chlorella vulgaris ESP-31.
► The highest lipid content and productivity were 53% and 144 mg/l/d, respectively.
► Composition of the microalgal lipids is suitable for biodiesel synthesis.