Accumulation of eicosapentaenoic acid in Nannochloropsis sp. in response to elevated CO2 concentrations

Abstract

To increase eicosapentaenoic acid (EPA, 20:5, n-3) content in the marine alga Nannochloropsis sp., the effect of CO 2 concentration during cultivation has been investigated. In a batch culture under normal atmospheric conditions (0.037% CO 2 ), the EPA content per cell increased during the first 1.5 days and then decreased immediately even though the cells were in an exponential growth phase. Increasing the CO 2 concentration to 0.3% and 2% over day 1.5 retained the EPA content at the higher concentration for another 1 and 2 days, respectively, suggesting that the EPA accumulation is enhanced by elevated concentrations of CO 2 . EPA accumulation in response to elevated CO 2 concentrations was also observed during a later growth phase when CO 2 was introduced after the decrease of EPA content. The addition of CO 2 caused a slight decrease in the pH of the medium though this was not the cause of the observed EPA accumulation as addition of acidic buffer did not affect the EPA content. The maximum EPA production was obtained when 2% CO 2 was supplied 12 h prior to the end of the exponential growth. The total EPA production during 4-day cultivation was about twice that obtained with ambient air. These results suggest that the available CO 2 concentration affects the EPA content in Nannochloropsis sp.

Response of Growth and Fatty Acid Compositions of Nannochloropsis sp. to Environmental Factors Under Elevated CO2 Concentration

“…was not limited by the supply of CO 2 (Hoshida et al 2005). Accordingly, nitrate and phosphate would be the key limiting nutrient for algal growth.…”

“…In recent years, there is a growing interest in improving the EPA production of this alga by optimizing environmental parameters. Elevated CO 2 or added organic carbon sources dramatically enhanced its cell growth and EPA production (Hu and Gao 2003;Hoshida et al 2005). Changes in environmental factors may, though, alter polyunsaturated fatty acids (PUFAs) content in microalgal species.…”

“…However, little is known about the environmental and nutritional effects on EPA production by Nannochloropsis sp. under elevated CO 2 concentrations (Hoshida et al 2005).…”

Assessment of the shelf life of Nannochloropsis oculata flocculates stored at different temperatures

“…It is Japanese in origin and its size varies from 2 to 3 µm . N. oculata has been suggested as a preferable foodstuff for the rotifer, Brachionus plicatilis, which efficiently transfers polyunsaturated fatty acids from the microalgae to marine fish larvae (Sukenik et al, 1993, Hoshida et al, 2005. In the study carried out by Brown et al (1999), the cultures reached densities of 8x10 6 to 20x10 6 cell mL -1 and growth rates of 0.7 to 1.13 day -¹ (López et al, 2007;Sánchez-Torres et al, 2008).…”

PRODUCCIÓN DE LA MICROALGA Nannochloropsis oculata (Droop) Hibberd EN MEDIOS ENRIQUECIDOS CON ENSILADO BIOLÓGICO DE PESCADO

“…Esta microalga pertenece a la clase Eustigmatophyceae, que agrupa a las especies que contienen la mayor cantidad de ácidos grasos poliinsaturados (PUFAs), especialmente ácido eicosapentaenoico (EPA), ácido araquidónico (ARA), docosahexaenoico (DHA) de gran importancia en la nutrición de animales marinos, especialmente en el crecimiento y desarrollo de larvas de peces, moluscos y crustáceos (Otero et al, 1997;Brown et al, 1999). La microalga N. oculata ha sido sugerida como un alimento preferible para el rotífero Brachionus plicatilis Mueller, el cual transfiere eficientemente los ácidos grasos poliinsaturados algales a las larvas de peces marinos (Sukenik, et al, 1993;Hoshida et al, 2005).…”