Factorial Optimization of Ultrasound-Assisted Extraction of Phycocyanin from Synechocystis salina: Towards a Biorefinery Approach

Abstract

PC is a bioactive and colorant compound widely sought in the food, nutraceutical and cosmetic industries, and one of the most important pigments produced by Synechocystis salina . However, the general extraction process is usually time-consuming and expensive, with low extraction yields—thus compromising a feasible and sustainable bioprocess. Hence, new extraction technologies (e.g., ultrasound assisted-extraction or UAE) emerged in the latest years may serve as a key step to make the overall bioprocess more competitive. Therefore, this study aimed at optimizing the yields of phycocyanin (PC) rich-extracts of S. salina by resorting to UAE; in attempts to explore this process in a more economically feasible way; valorization of the remaining cyanobacterial biomass, via extraction of other bioactive pigments and antioxidants, was tackled within a biorefinery perspective. A two-stage extraction (using ethanol and water) was thus performed (because it favors PC extraction); other bioactive pigments, including chlorophyll a (chl a), carotenoids, and other phycobiliproteins (PBPs), but also antioxidant (AOX) capacity and extraction yields were also evaluated for their optimum UAE yields. A factorial design based on Box–Behnken model was developed; and the influence of such extraction parameters as biomass to solvent ratio (B/S ratio = 1.5-8.5 mg·mL−1), duty cycle (DT = 40-100%), and percentage of amplitude (A = 40-100%) were evaluated. The model predicted higher PC yields with high B/S ratio = 6 mg·mL−1, lower DT = 80% and an A=100%. Classical extraction was compared with UAE under the optimum conditions found; the latter improved PC yields by 12.5% and 47.8%, when compared to freeze-thawing extraction, and bead beater homogenization-based extraction, respectively. UAE successive extractions allowed to valorize other important bioactive compounds than PC, by reusing biomass, supporting a favorable contribution to the economic feasibility of the S. salina-based process towards a biorefinery approach.

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

“…In the case of S. salina , it appears that the potential predictive response has to cope with low temperatures. Low temperatures and high salinities were indeed reported to enhance the PUFA content [ 8 , 56 ], as those fatty acids promote the fluidity of cell membranes, thus preserving the photosynthetic machinery and achieving physiological homeostasis [ 61 , 62 ].…”

“…Phycobiliproteins (PBPs), antioxidants, lipidic components (e.g., carotenoids and polyunsaturated fatty acids (PUFAs)), phenolic compounds, and proteins, among others, are some of the most important explored compounds recovered from cyanobacteria. Those compounds exhibit several pharmacological bioactivities, including antioxidant, antitumor, anti-inflammatory, cardiovascular, and neuro- and hepatoprotective properties [ 6 , 7 , 8 ]. Due to their non-toxic nature, they also have a potential application as natural food and feed ingredients or colorants (specifically phycobiliproteins and carotenoids in the context of cosmetic formulation, biomedical research, or clinical diagnostics) [ 4 , 5 , 9 ].…”

Ultrasonic control of aquatic macrophytes in reservoirs: An integrated review

“…Ultrasound techniques are used in various fields, such as chemical engineering for dispersing nanoparticles, accelerating chemical reactions, extracting bioactive compounds, and emulsification; in environmental engineering for Research, Society and Development, v. 13, n. 6, e2213645914, 2024 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v13i6.45914 11 applications like wastewater treatment, water disinfection, soil remediation, and controlling cyanobacteria and algae, in industrial cleaning, and in separation and extraction processes (Assunção et al, 2022;Cai et al, 2014;Fetyan & Salem Attia, 2020;Kist et al, 2020;Kitamura et al, 2023;Long et al, 2021;Pacheco-Álvarez et al, 2022); in medicine for diagnostics and treatment; in the food industry for processing and preservation (Dolas et al, 2019;Gallo et al, 2018;Song et al, 2021;Zhu et al, 2023). Ultrasound is also applied in the pharmaceutical industry and in nanotechnology for material synthesis.…”

Design of Experiments for Optimizing Ultrasound-Assisted Extraction of Bioactive Compounds from Plant-Based Sources

“…These designs, along with predictive statistical tools based on mathematical models such as response surface methodology, aim to optimize extraction conditions and generalize experimental results. This approach makes it feasible to understand the potential for process scale-up [16,19,21,[23][24][25].…”