Characterization of Nitrogen Stress-induced Growth, Proximate, and Pigment Contents of Nannochloropsis sp.

Abstract

Nitrogen is one of the key growth factors and structural constituent of the cellular molecules of Nannochloropsis sp. This study aimed to determine the influence of nitrogen stress in the form of potassium nitrate (KNO3 ) by altering the standard recommended nitrogen concentration to characterize the growth performance, proximate composition, and pigments content. The nitrogen concentration was arranged in following order for the culture of Nannochloropsis sp.: 50 g/L, 75 g/L, 100 g/L (standard), 125 g/L, and 150 g/L of KNO3 . All growth parameters, proximate composition, and pigment contents showed significant (p < 0.05) changes among the treatments. Cell density was increased by 2.48 folds, SGR was increased by 56.9%, and cells were doubled in number at a pace of 12.192 hours faster at the maximum nitrogen concentration (150g/L KNO3 ). The maximum protein content was 54 ± 1.05% at 150 g/L KNO3 while the highest lipid content was 36 ± 0.32% at 75 g/L KNO3 . The highest carbohydrate content was 24 ± 2.51% at 100 g/L KNO3 . The chlorophyll a content was increased to 0.632 ± 0.049 µg/L at 150 g/L KNO3 , while the highest carotenoids content was 3.301 ± 0.052 µg/ml at the 75g/L KNO3 . On the other hand, phycobiliprotein content was the highest 0.028 mg/g for the standard concentration of KNO3 . This study provides the commercial cultivation strategy for Nannochloropsis sp. by revealing the biomass productivity, biochemical and bioactive compounds status at different nitrogen-based culture conditions that will ensure their multipurpose use in aquaculture, pharmaceuticals, and nutraceuticals sectors.