Microalgae are valuable sources of bioactive compounds. However, their production requires strategies to enhance metabolic responses. This study explores how Chlorella vulgaris responds to different salinity conditions using a two-stage cultivation strategy, assessing the change in amino acid and carotenoid content on microalgae over time. First, microalgae were cultivated under optimal conditions, followed by exposure to different salinity levels (150 mM and 300 mM NaCl). Growth kinetics, nutrient uptake, and biochemical composition were analysed, revealing distinct salinity-induced responses. Similar specific growth rates were achieved across all assays, while nitrate removal improved under salinity and phosphate uptake decreased. Amino acid profiling showed significant declines in the content of several compounds and carotenoid content also presented declining trends, although moderate salinity mitigated degradation in key pigments. Principal component analysis identified high correlations between amino acids and carotenoids contents, forming groups of compounds with similar variations. These findings contribute to a better understanding of the salinity-induced response of C. vulgaris, offering insights for biotechnology applications. By optimising cultivation conditions, salinity could enhance bioactive compound retention, supporting the development of sustainable microalgae-based products.

Interest in microalgae-based technologies has emerged in recent years as a response to environmental challenges and the global food crisis, for providing alternative and sustainable food products. This study used temperature variations between 18 and 32 °C and nitrogen-to-phosphorus (N:P) ratios between 1.9 and 42.6 to model and optimize growth and composition of Chlorella vulgaris, a nutritionally interesting species. Lower temperatures appear ideal for this strain. An increase in average biomass productivity was observed with decreasing temperature, leading to a maximum of 122.27 mg_dw L⁻¹ d⁻¹ at 18 °C on the fourth day of cultivation. The maximum productivities for total proteins, fatty acids, carbohydrates, and pigments were, respectively, 26.9 mg L⁻¹ d⁻¹, 26.4 mg L⁻¹ d⁻¹, 16.0 mg L⁻¹ d⁻¹, and 2.41 mg L⁻¹ d⁻¹, all referring to 18 °C. The fatty acid, carotenoid, and amino acid profiles were also ascertained; several indicators suggested that cultivation of these microalgae under the aforementioned optimal conditions holds potential for the food industry. The high proportion of polyunsaturated fatty acids—including two essential fatty acids; the high production of lutein, and the presence of several essential amino acids are among the favorable indicators. Overall, the information generated by this study is helpful to support future pilot studies aimed at the commercial production of microalgae-derived products.

Interest in microalga-based technologies has emerged in recent years as a response to environmental challenges and the global food crisis for providing alternative and sustainable food products. This study used temperature variations between 18 and 32 °C, and nitrogen-to-phosphorus (N:P) ratios between 1.9 and 42.6, to model and optimize growth and composition of Chlorella vulgaris, a nutritionally interesting species. Lower temperatures appear ideal for this strain. An increase in average biomass productivity was observed with decreasing temperature, leading to a maximum of 122.27 mg_dw L^-1 d^-1 at 18 °C on the 4^th day of cultivation. The maximum productivities for total proteins, fatty acids, carbohydrates, and pigments were, respectively, 26.9 mg L^-1 d^-1, 26.4 mg L^-1 d^-1, 16.0 mg L^-1 d^-1, and 2.41 mg L^-1 d^-1, all referring to 18 °C. The fatty acid, carotenoid, and amino acid profiles were also ascertained; several indicators suggested that cultivation of this microalga under the aforementioned optimal conditions holds potential for the food industry. The high proportion of polyunsaturated fatty acids, including two essential fatty acids; the high production of lutein; and the presence of several essential amino acids are among the favorable indicators. Overall, the information generated by this study is helpful to support future pilot studies aimed at the commercial production of microalga-derived products.