Effect of nitrate depletion on lipid accumulation by the marine microalga Nannochloropsis oculata

Abstract

Nannochloropsis oculata is a marine algae with high lipid content, being a promising species for biofuel production. It is also used as food in aquaculture for larval fish and crustaceans due to its high nutritional value and compatible size with the larvae feeding. This study evaluated the lipid content in the biomass of N. oculata under nitrate depletion. The cultivation was carried out in 8 L bottles with three replications, at salinity 27, illuminance of 60 μE cm -2 s -1 and temperature 28 °C. The levels of sodium nitrate used were 15; 30; 45; 60 and 75 mg L -1 , while maintaining constant the levels of all other nutrients of the Guillard f/2 medium. The growth curve was monitored every two days by spectrophotometry at 680 nm (DO680nm) and cell counting in a Neubauer chamber. For separation of the culture medium from the cells, we used chemical flocculation method, adding 2N NaOH. The higher lipid content in the biomass was obtained at the lowest level of nitrate in the culture medium. Keywords

Plankton: Environmental and Economic Importance for a Sustainable Future

“…Algae are considered a pool of several compounds with biological activities [21,22]. The algal composition varies according to environmental conditions, thus there are species with different concentrations of proteins, polysaccharides, pigments and fatty acids [23].…”

Phytorremediation of urban and fish farming wastewater and growth performance responses of Litopenaeus vannamei using microalgae Chlorella vulgaris

“…The microalgae had an initial dry weight of 0.194, 0.196 and 0.191 g L -1 for STS, FF and SM, respectively. After eight days of cultivation, the algal biomass was recovered by chemical flocculation using 2N NaOH, washed to remove the fluctuant and dried in oven with air renewal at 60 °C for 24 h (Silva et al, 2015).…”

“…Microalgae can remove more than 95% of nitrogen compounds and 90% of phosphorus in effluents (Praveen;Loh, 2016). The use of native algae, such as Chlorella vulgaris, in the phytoremediation of wastewater is very important because the species presents rapid cell growth, CO 2 removal, oxygen production, resistance to contamination, excellent biochemical composition and efficient nutrient absorption (Rodrigues-Sousa et al, 2021;Miao et al, 2016;Silva et al, 2015). C. vulgaris was used by Wang et al (2017), to evaluate the capacity to remove nitrogen in the form of ammonia or ammonium ion, being able to drastically remove nitrogen compounds in just 48 h, showing its high potential for wastewater treatment.…”