Effect of irradiance and nitrogen source on the growth, cell size, and the content of proteins, carbohydrates and lipids of Scenedesmus acuminatus
摘要
This study evaluated the effects of nitrogen source and irradiance on the growth, cell size, biomass production and proximate composition of Scenedesmus acuminatus, a native strain isolated from Baja California, Mexico. Cultures were maintained with two nitrogen sources (nitrate and ammonium) at a final concentration of 17.66 × 10–4 M and three irradiance levels (50, 100, and 200 μmol photons m−2 s−1). The highest growth rate (0.479 ± 0.01 divisions day−1) was obtained under low irradiance (50 μmol photons m⁻2 s⁻1) with ammonium. Increased irradiance promoted greater cell width under nitrate, particularly during the stationary phase. Protein content during the stationary phase with ammonium under low irradiance peaked at 26.5% (50 μmol photons m−2 s−1) and 27.1% (100 μmol photons m−2 s−1). The highest lipid content (28.0%) was observed during the exponential phase with ammonium at 50 μmol photons m−2 s−1, while maximum carbohydrate content (39.5%) occurred under nitrate at 200 μmol photons m−2 s−1 during exponential growth. Nitrate and irradiances of 100 and 200 μmol photons m−2 s−1 promoted higher values of total dry weight, whereas the use of ammonium increased the growth rate. These findings advance our understanding of S. acuminatus physiology and demonstrate its versatility for aquaculture and biotechnological applications. Its ability to accumulate proteins under low irradiance (50–100 μmol photons m−2 s−1), together with lipid and carbohydrate accumulation at higher light levels (200 μmol photons m−2 s−1), makes S. acuminatus a promising candidate for tailored biomass production—from larval feed and functional additives to substrates for biofuel generation—depending on specific culture objectives.