Factorial optimization of upstream process for Cyanobium sp. pigments production

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 aqueous 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.