Abstract: Cyanobacteria-based pigments, such as carotenoids and phycobiliproteins, have emerged in the last few years as products with great economical interest. However, only the production of a few strains has been optimized for large scale productions. As photosynthetic components, pigments have their synthesis modulated by abiotic factors, such as pH, temperature and salinity, which can lead to a huge impact on cyanobacteria production. This work aimed the optimization of biomass and pigments production by Cyanobium sp. LEGE 06113, using a factorial Box-Behnken design for three abiotic factors - temperature (20–30 °C), pH (6.0–9.0) and salinity (NaCl, 10–30 g L−1). Biomass, photosynthetic activity, carotenoid and phycobiliprotein productivity and antioxidant capacity of acetonic and aque ous extracts were measured over time and plotted into quadratic models. Results revealed that temperature and pH had a more significant impact than salinity on Cyanobium sp. metabolism and it was possible to determine a significant quadratic model for all evaluated parameters. According to the factorial modelling, the optimal condition for biomass, carotenoids and phycobiliprotein productivity was obtained at 20 °C, pH 9.0 and 10 g L−1 of NaCl, as subsequently confirmed in experimental trials, with an observed productivity of 127.12 ± 1.30 mgDW Lculture−1 day−1 for biomass; 2.04 ± 0.51 mgcarot Lculture−1 day−1 for total carotenoids; and 4.14 ± 0.71 mgphyco Lculture−1 day−1 for total phycobiliproteins

Fernando Pagels, Daniel Salvaterra, Helena M Amaro, Graciliana Lopes, Isabel Sousa-Pinto, Vitor Vasconcelos, A. Catarina Guedes