Recovery of lipophilic products from wild cyanobacteria (Aphanizomenon flos-aquae) isolated from the Curonian Lagoon by means of supercritical carbon dioxide extraction

Abstract

Cyanobacteria are widely distributed photosynthetic microorganisms that can be found in almost every terrestrial and aquatic environment. In heavily eutrophicated water bodies, massive proliferation of cyanobacteria can lead into excessive surface water blooms. Over the last decades the presence of Aphanizomenon sp. dominated blooms have also been reported in the Curonian Lagoon. Recent reports indicate that removal of wild cyanobacterial blooms from the Curonian Lagoon as a management measure should be prioritized. In this study, the utilization of wild cyanobacteria as a potential source of high-added value products by means of supercritical CO2 extraction (SFE-CO2) is reported. Central composite design (CCD) and response surface methodology (RSM) were employed to optimize SFE-CO2 parameters (temperature, pressure and time) to obtain high yield lipophilic extracts. Under optimal conditions (42.5 MPa, 55 °C and 120 min), SFE-CO2 yielded 4.43 g/100 g DW of non-polar extract, showing 20% higher extraction efficiency at 3-fold lower extraction time as compared to the conventional Soxhlet extraction. SFE-CO2 fraction was rich in α‑linolenic acid (27% of total fatty acids) and α‑tocopherol (293 μg/g extract). Moreover, the total phenolic content and the in vitro radical scavenging capacity of extracts and solid fractions were evaluated too. Furthermore, preliminary life cycle assessment (LCA) showed that SFE-CO2 had a higher life cycle impact as compared to the hexane system. Thus, SFE-CO2 could be utilized to valorise wild cyanobacteria into valuable products with various industrial applications.