Exploring the Physiological Multiplicity of Native Microalgae from the Ecuadorian Highland, Italian Lowland and Indoor Locations in Response to UV-B

Abstract

The differential effects of UV-B on the inhibition or activation of protective mechanisms to maintain cells photosynthetically active were investigated in native microalgae. Four strains were used, including two Chlorella sorokiniana strains, F4 and LG1, isolated from a Mediterranean inland swamp and a recycled cigarette butt’s substrate, respectively, and two isolates from an Ecuadorian highland lake related to Pectinodesmus pectinatus (PEC) and Ettlia pseudoalveolaris (ETI). Monocultures were exposed to acute UV-B (1.7 W m−2) over 18 h under controlled conditions. UV-B-untreated microalgae were used as the control. Comparative physiological responses, including photosynthetic pigments, non-enzymatic antioxidants, and chlorophyll a fluorescence, were evaluated at specific time points. Results showed that UV-B significantly compromised all the physiological parameters in F4, thereby resulting in the most UV-B-sensitive strain. Contrarily, UV-B exposure did not lead to changes in the PEC physiological traits, resulting in the best UV-B-resistant strain. This could be attributed to the acclimation to high light habitat, where maintaining a constitutive phenotype (at the photosynthetic level) is strategically advantageous. Differently, LG1 and ETI at 12 h of UV-B exposure showed different UV-B responses, which is probably related to acclimation, where in LG1, the pigments were recovered, and the antioxidants were still functioning, while in ETI, the accumulation of pigments and antioxidants was increased to avoid further photodamage. Consequently, the prolonged exposure in LG1 and ETI resulted in species-specific metabolic regulation (e.g., non-enzymatic antioxidants) in order to constrain full photoinhibition under acute UV-B.

In Vitro Characterization of Antioxidant, Antibacterial and Antimutagenic Activities of the Green Microalga Ettlia pseudoalveolaris

“…Bold) Shin Watanabe and G.L. Floyd, (accession number OP136137) freshwater microalgae isolated in the Plant Biotechnology Laboratories of the North-Technical University (Universidad Técnica del Norte, Ibarra, Ecuador Available online: (accessed on 23 May 2023)) was used [ 18 ]. Cultivation samples were pre filtered in 0.2 µm pore size filters to concentrate biomass and cultivated in 250 mL Erlenmeyer Flasks with 150 mL of culture media.…”

“…Optical densitity (OD) was measured at 750 nm three times at day by duplicate in an UV-VIS spectophotometer (Jenway 6705 UV/Vis). At the same time, cell number was measured by Neubauer chamber [ 18 ].…”

“…Finally, Saccharomyces cerevisiae yeast strain D7 was used as a model organism to determine the potential genotoxic and protective effect on oxidation-induced damage. [18]. Cultivation samples were pre filtered in 0.2 µm pore size filters to concentrate biomass and cultivated in 250 mL Erlenmeyer Flasks with 150 mL of culture media.…”

Chlamydomonas agloeformis from the Ecuadorian Highlands: Nutrients and Bioactive Compounds Profiling and In Vitro Antioxidant Activity

“…KNO 3 was used as a nitrogen source in different concentrations (1, 3, 5 g/L), and K 2 HPO 4 as a phosphate source (0.5 and 0.7 g/L). Additionally, Murashige and Skoog (Duchefa Biochemie, BH Haarlem, the Netherlands) medium (4.4 g/L) was used with extra nitrogen source as KNO 3 (2.0 g/L) and phosphate (0.5 g/L) [15]. All media were prepared with 0.3 g/L of NaHCO 3 , adjusted at pH 7, and autoclaved for sterilization.…”