The Influence of Temperature and Type of Illumination on the Biochemical Composition and EPA Production of Nannochloropsis gaditana

Nannochloropsis gaditana is a marine microalgae well appreciated in aquaculture due to its nutritional value and valuable chemical compounds, like EPA. Cultures of Nannochloropsis gaditana were carried out in tubular bubble reactors, sparged with a flow rate of 120 ml min−1 of air and submitted to a 12:12 h light/dark regimen. Two factors have been tested: temperature and type of illumination (fluorescent and halogen lamps). Different light intensities were also used, respectively 15 µE for fluorescent lamps and 33 µE for halogen lamps. The effect of light intensity by fluorescent lamps on the cell growth rate and cell biochemical composition was studied at 7, 11 and 16 µE. Low temperature and the type of light source were found to be determinant either on the growth rate and on pigments and fatty acids production. Fluorescent lamp illumination is more favourable. Both the use of fluorescent lamps and the increase of light intensity (low range) led to higher cell growth rates, as well as an increase of the total fatty acids content. The last increase is mainly due to the accumulation of storage lipids. However, increasing the light intensity does not favour the EPA content of the cells.