Growth, lipid content, and fatty acid profile of freshwater cyanobacteria Dolichospermum affine (Lemmermann) Wacklin, Hoffmann, & Komárek by using modified nutrient media

In this study, Dolichospermum affine was cultivated under starvation and limitation conditions, using six different concentrations of nitrate (NaNO 3 ) and phosphate (K 2 HPO 4 ) in BG-11 medium. The biomass, pigments, proteins, carbohydrates, lipids, triacylglycerol-TAG, and fatty acid responses to different modified media were examined in terms of cell density, dry biomass, optical density, growth rate, chlorophyll-a, carotene content, and lipid productivity. Molecular characterization of D . affine isolates was performed using Fourier transform–infrared spectroscopy (FT-IR) and polymerase chain reaction (PCR). In the 20-day batch culture period, one of the modified media, %50 N and P limitation (N-P Limitation ), exhibited higher values than the others in terms of cell density (1.41 × 10 7 cells/mL), dry biomass (1.68 gL −1 ), optical density (1.26), growth rate (0.48 day −1 ), chlorophyll-a (3.76 μg L −1 ), and total carotenoid (12.99 μg L −1 ). The maximum percentage lipid content of D . affine was obtained in the control group at 10.67%. Fatty acid profiles have been investigated in six conditions and consisted of 10 fatty acids. The basic saturated fatty acid palmitic acid was (C16:0) for all conditions, and its rate was 40.61% for starvation of N and P (N-P Deprivation ) conditions. Oleic acid (C18:1) rate was detected in all groups, but the highest rate was found in the control group with 33.72%. In all conditions, TAG values were found similar, but the highest value was determined at 50% P and 100% N (P Limitation -N Control ) (27.5%) modified media. Carbohydrate content (20.37%) was found to be high under N and P starvation (N-P Deprivation ), while protein content (66.92%) was high under 50% N and 100% P (N Limitation -P Control ) conditions. The results obtained from this study showed that nitrogen and phosphorus starvation and limitation affecting the biomass, valuable secondary metabolites and lipid accumulation and affected the fatty acid composition of D . affine cultures.