Effects of Temperature, pH, and NaCl Concentration on Biomass and Bioactive Compound Production by Synechocystis salina

• Published in: Life (Basel, Switzerland) Switzerland), 2023-01, Vol.13 (1), p.187
• Main Authors: Assunção, Joana, Amaro, Helena M, Tavares, Tânia, Malcata, F Xavier, Guedes, A Catarina
• Format: Article
• Language: English
• Subjects: antioxidant capacity; Antioxidants; Bioactive compounds; Biodiesel fuels; Biological activity; Biomass; Bioremediation; Biotechnology; Box–Behnken model; Carotenoids; Cyanobacteria; Factorial design; Factorial experiments; Fluorescent lighting; Light; optimization; pH effects; Phycocyanin; pigments; Sodium chloride; Synechocystis salina; Temperature effects
• ISSN: 2075-1729; 2075-1729
• DOI: 10.3390/life13010187

is a cyanobacterium that has biotechnological potential thanks to its ability to synthesize several bioactive compounds of interest. Therefore, this study aimed to find optimal conditions, in terms of temperature (15-25 °C), pH (6.5-9.5), and NaCl concentration (10-40 g·L ), using as objective functions the productivities of biomass, total carotenoids, total PBPs, phycocyanin (PC), allophycocyanin (APC), phycoerythrin (PE), and antioxidants (AOXs) capacity of ( ) strain LEGE 06155, based in factorial design resorting to Box-Behnken. The model predicted higher biomass productivities under a temperature of 25 °C, a pH of 7.5, and low NaCl concentrations (10 g·L ). Maximum productivities in terms of bioactive compounds were attained at lower NaCl concentrations (10 g·L ) (except for PE), with the best temperature and pH in terms of carotenoids and total and individual PBPs ranging from 23-25 °C to 7.5-9.5, respectively. PE was the only pigment for which the best productivity was reached at a lower temperature (15 °C) and pH (6.5) and a higher concentration of NaCl (≈25 g·L ). AOX productivities, determined in both ethanolic and aqueous extracts, were positively influenced by lower temperatures (15-19 °C) and higher salinities (≈15-25 g·L ). However, ethanolic AOXs were better recovered at a higher pH (pH ≈ 9.5), while aqueous AOXs were favored by a pH of 8. The model showed that biomass production can be enhanced by 175% (compared to non-optimized conditions), total carotenoids by 91%, PC by 13%, APC by 50%, PE by 130%, and total PBPs by 39%; for AOX productivities, only water extracts exhibited a (marginal) improvement of 1.4%. This study provided insightful information for the eventual upgrading of biomass in the biotechnological market.