Search Results (30)

The nanoencapsulation of bioactive compounds such as β-carotene and microalgal extracts has emerged as an effective strategy to enhance their stability, bioavailability, and biological efficacy, particularly against oxidative stress. Dunaliella tertiolecta, a microalga rich in carotenoids and chlorophylls, presents notable antioxidant and erythroprotective properties; however, its bioactive potential is limited by low bioaccessibility and degradation during processing and digestion. This study aimed to develop and evaluate nanoliposomes loaded with D. tertiolecta extract and β-carotene as sustained-release systems to improve antioxidant performance and erythroprotective effects. The methodology involved optimizing microalgal cultivation under nitrogen and salinity stress to enhance pigment accumulation, followed by extraction, nanoencapsulation via the particle dispersion method, and physicochemical characterization of the nanoliposomes. Antioxidant capacity and release kinetics were assessed through ABTS and FRAP assays, while erythroprotective activity was evaluated by monitoring oxidative hemolysis in human erythrocytes. The release kinetics revealed an anomalous transport mechanism for both systems, with β-carotene showing faster and more efficient release due to its greater lipophilic compatibility with the nanoliposomal matrix. The nanoliposomal systems demonstrated nanoscale size, high encapsulation efficiency, sustained antioxidant release, and effective erythrocyte protection, with the extract-loaded formulation exhibiting synergistic effects superior to isolated β-carotene. These findings support the potential application of this nanotechnology-based delivery system in functional foods, nutraceuticals, and biomedical formulations aimed at preventing oxidative stress-related cellular damage. Full article

Fludioxonil is a widely used fungicide that is frequently used to combat fungal plant diseases. Consequently, excessive concentrations of fludioxonil may enter and accumulate over time in aquatic systems, harming (micro) organisms in several ways. Thus, it is of great importance to evaluate the potential toxic effects of fludioxonil using bioassays. In the present study, various in vitro assays were used to assess the possible effects of fludioxonil in human cells and aquatic microorganisms. For the investigation of the toxic effects of fludioxonil on freshwater microalgae, Scenedesmus rubescens and Dunaliella tertiolecta were exposed to various environmentally relevant concentrations of the fungicide for a period of 96 h. Fludioxonil at 50–200 μg L⁻¹ significantly limited the growth of both microalgae, especially in the first 24 h of the exposure, where inhibitions up to 82.34% were calculated. The toxicity of fludioxonil was further evaluated via the Microtox test, and the studied fungicide was found to be less toxic for the bacteria Aliivibrio fischeri. Regarding human cells, the fludioxonil’s toxic and cyto-genotoxic effects were assessed using the Trypan blue exclusion test and the Cytokinesis Block MicroNucleus (CBMN) assay. Cell viability in all fludioxonil-treated concentrations was similar to control values according to the results of the Trypan blue exclusion test. However, the CBMN assay was used and revealed that fludioxonil had genotoxic potential in higher concentrations and exerted cytotoxic activity against human lymphocytes. Specifically, only the highest dose of fludioxonil, i.e., 10 μg mL⁻¹, exerted genotoxic effects against human lymphocytes, whereas treatment with 0.5, 1, and 5 μg mL⁻¹ did not lead to statistically significant induction of micronuclei (MN) frequencies compared with the control culture. However, fludioxonil-mediated cytotoxicity was statistically significant, which was demonstrated by the decreased CBPI (cytokinesis block proliferation index) values in all cases except for the lowest dose, i.e., 0.5 μg mL⁻¹. Full article

The rapid growth of the dairy industry has resulted in a significant increase in the generation of effluents, which are characterized by a high organic content that poses environmental challenges. In alignment with sustainable practices and the principles of the circular economy, this study investigates the valorization of cheese whey (CW) effluents through the cultivation of the microalga Dunaliella tertiolecta under mixotrophic conditions. The research aims to utilize cheese whey effluents as a supplemental growth medium to enhance the production of algal biomass and extracellular polymeric substances (EPSs). The results reveal that CW facilitated a 37% improvement in D. tertiolecta growth and led to an approximately eight times greater biomass productivity compared to under photoautotrophic conditions, while the EPS production increased by 30%. Chemical and techno-functional analyses of the microalgal biomass and EPSs suggest promising applications as natural product additives for the food industry. Biomass derived from photoautotrophic culture demonstrated greater antioxidant activity and total polyphenols content. Additionally, the lipid profile revealed 16 distinct fatty acids. On the other hand, biomass from the mixotrophic culture exhibited higher protein levels and eight fatty acids, indicating the influence of the cultivation mode on the biochemical composition. Regarding the EPSs, mixotrophic cultivation resulted in elevated antioxidant activity and total polyphenols content, as well as higher protein and sugar levels. Furthermore, the EPSs produced under mixotrophic conditions exhibited superior techno-functional properties compared to those of the photoautotrophic culture, making them ideal candidates for use as alternative natural food additives. Full article

Biomass harvesting represents one of the main bottlenecks in microalgae large-scale production. Solid–liquid separation of the biomass accounts for 30% of the total production costs, which can be reduced by the use of flocculants as a pre-concentration step in the downstream process. The natural polymer chitosan and the two chemical flocculants FeCl₃ and AlCl₃ were tested on freshwater Chlorella sorokiniana and two marine algae, Dunaliella tertiolecta and Tetraselmis striata. A preliminary screening at the laboratory scale was performed to detect the most suitable doses of flocculants. On the basis of these results, selected doses were tested on the pilot scale, using the flocculants for a pre-concentration step and the centrifugation as a second step to confirm the effectiveness of flocculants in a realistic operational environment. The biomass recoveries (R_pilot, %) of 100 L cultures were as follows: (1) for T. striata, R_pilot = 94.6% for 0.08 g/L AlCl₃, 88.4% for 0.1 g/L FeCl₃, and 68.3% for 0.04 g/L chitosan; (2) for D. tertiolecta, R_pilot = 81.7% for 0.1 g/L AlCl₃, 87.9% for 0.2 g/L FeCl₃, and 81.6% for 0.1 g/L chitosan; and (3) for C. sorokiniana, R_pilot = 89.6% for 0.1 g/L AlCl₃, 98.6% for 0.2 g/L FeCl₃, and 68.3% for 0.1 g/L chitosan. Flocculation reduced the harvesting costs by 85.9 ± 4.5% using chemical flocculants. Excesses of aluminum and iron in the biomass could be solved by decreasing the pH in the biomass combined with washing. This is the first study, to the best of our knowledge, that investigates the pilot-scale flocculation of three native Canarian microalgal strains. A pilot-scale pre-concentration step before centrifugation can improve the yield and reduce costs in the microalgae harvesting process. Full article

Cultured meat technology is a form of cellular agriculture where meat is produced from animal cells grown in a lab, instead of raising and slaughtering animals. This technology relies heavily on fetal bovine serum (FBS) in cell media; hence, production is costly and contributes significantly to ammonia and greenhouse gas emissions. Achieving the successful commercialization of cell-cultured food requires the critical resolution of manufacturing cost and safety concerns. Hence, our research efforts are focused on identifying commercially viable and ecologically sustainable alternatives to FBS. In this study, we evaluated the potential of twenty-six water-based algal and cyanobacterial extracts to stimulate cell growth for meat cultivation under 90% reduced serum conditions. The extracts were compared in viability, proliferation, and Trypan blue exclusion assays. In the first screening phase, the extracts were evaluated in a ZEM2S (zebrafish) cell culture in a 1% FBS regimen. Based on their ability to exhibit protein tolerance or promote cell proliferation, ten extracts were selected and further assayed in a QM7 cell culture. The QM7 cell line (myoblasts from Japanese quail) is highly relevant for meat cultivation because of its ability to differentiate into muscle fibers. Extracts derived from two microalgae species, Arthrospira platensis (Spirulina) and Dunaliella tertiolecta, demonstrated the highest tolerance in cell culture, above 10 μg/mL (expressed as total protein concentration). Tolerance at a 100 μg/mL concentration was demonstrated exclusively using an extract of blue spirulina (commercially purified Spirulina), which supported cell growth through multiple passages. Full article

Nano- and micro-sized vesicular and colloidal structures mediate cell–cell communication. They are important players in the physiology of plants, animals, and humans, and are a subject of increasing interest. We investigated the effect of three surfactants, N-cetylpyridinium chloride (CPC), sodium dodecyl sulfate (SDS), and Triton X-100 (TX100), and two anionic polyelectrolytes, sodium polystyrene sulfonate (NaPSS) and sodium polymethacrylate (NaPMA), on nanoliposomes. In addition, the effect of SDS and TX100 on selected biological membranes (erythrocytes and microalgae) was investigated. The liposomes were produced by extrusion and evaluated by microcalorimetry and light scattering, based on the total intensity of the scattered light (I_tot), hydrodynamic radius (R_h), radius of gyration (R_g), shape parameter p (=R_h/R_g,0), and polydispersity index. The EPs shed from erythrocytes and microalgae Dunaliella tertiolecta and Phaeodactylum tricornutum were visualized by scanning electron microscopy (SEM) and analyzed by flow cytometry (FCM). The R_h and I_tot values in POPC liposome suspensions with added CPC, SDS, and TX100 were roughly constant up to the respective critical micelle concentrations (CMCs) of the surfactants. At higher compound concentrations, I_tot dropped towards zero, whereas R_h increased to values higher than in pure POPC suspensions (R_h ≈ 60–70 nm), indicating the disintegration of liposomes and formation of larger particles, i.e., various POPC–S aggregates. Nanoliposomes were stable upon the addition of NaPSS and NaPMA, as indicated by the constant R_h and I_tot values. The interaction of CPC, SDS, or TX100 with liposomes was exothermic, while there were no measurable heat effects with NaPSS or NaPMA. The SDS and TX100 increased the number density of EPs several-fold in erythrocyte suspensions and up to 30-fold in the conditioned media of Dunaliella tertiolecta at the expense of the number density of cells, which decreased to less than 5% in erythrocytes and several-fold in Dunaliella tertiolecta. The SDS and TX100 did not affect the number density of the microalgae Phaeodactylum tricornutum, while the number density of EPs was lower in the conditioned media than in the control, but increased several-fold in a concentration-dependent manner. Our results indicate that amphiphilic molecules need to be organized in nanosized particles to match the local curvature of the membrane for facilitated uptake. To pursue this hypothesis, other surfactants and biological membranes should be studied in the future for more general conclusions. Full article

The salt-tolerant marine microalgae Dunaliella tertiolecta is reported to generate significant amounts of intracellular glycerol as an osmoprotectant under high salt conditions. This study highlights the phylogenetic distribution and comparative glycerol biosynthesis of seven new Dunaliella isolates compared to a D. tertiolecta reference strain. Phylogenetic analysis indicates that all Dunaliella isolates are newly discovered and do not relate to the D. tertiolecta reference. Several studies have identified light color and intensity and salt concentration alone as the most inducing factors impacting glycerol productivity. This study aims to optimize glycerol production by investigating these described factors singularly and in combination to improve the glycerol product titer. Glycerol production data indicate that cultivation with white light of an intensity between 500 and 2000 μmol m⁻² s⁻¹ as opposed to 100 μmol m⁻² s⁻¹ achieves higher biomass and thereby higher glycerol titers for all our tested Dunaliella strains. Moreover, applying higher light intensity in a cultivation of 1.5 M NaCl and an increase to 3 M NaCl resulted in hyperosmotic stress conditions, providing the highest glycerol titer. Under these optimal light intensity and salt conditions, the glycerol titer of D. tertiolecta could be doubled to 0.79 mg mL⁻¹ in comparison to 100 μmol m⁻² s⁻¹ and salt stress to 2 M NaCl, and was higher compared to singularly optimized conditions. Furthermore, under the same conditions, glycerol extracts from new Dunaliella isolates did provide up to 0.94 mg mL⁻¹. This highly pure algae-glycerol obtained under optimal production conditions can find widespread applications, e.g., in the pharmaceutical industry or the production of sustainable carbon fibers. Full article

With the increasing rate of the antimicrobial resistance phenomenon, natural products gain our attention as potential drug candidates. Apart from being used as nutraceuticals and for biotechnological purposes, microalgae and phytoplankton have well-recognized antimicrobial compounds and proved anti-infectious potential. In this review, we comprehensively outline the antimicrobial activity of one genus of cyanobacteria (Arthrospira, formerly Spirulina) and of eukaryotic microalgae (Dunaliella). Both, especially Arthrospira, are mostly used as nutraceuticals and as a source of antioxidants for health supplements, cancer therapy and cosmetics. Their diverse bioactive compounds provide other bioactivities and potential for various medical applications. Their antibacterial and antifungal activity vary in a broad range and are strain specific. There are strains of Arthrospira platensis with very potent activity and minimum inhibitory concentrations (MICs) as low as 2–15 µg/mL against bacterial fish pathogens including Bacillus and Vibrio spp. Arthrospira sp. has demonstrated an inhibition zone (IZ) of 50 mm against Staphylococcus aureus. Remarkable is the substantial amount of in vivo studies of Arthrospira showing it to be very promising for preventing vibriosis in shrimp and Helicobacter pylori infection and for wound healing. The innovative laser irradiation of the chlorophyll it releases can cause photodynamic destruction of bacteria. Dunaliella salina has exhibited MIC values lower than 300 µg/mL and an IZ value of 25.4 mm on different bacteria, while Dunaliella tertiolecta has demonstrated MIC values of 25 and 50 μg/mL against some Staphylococcus spp. These values fulfill the criteria for significant antimicrobial activity and sometimes are comparable or exceed the activity of the control antibiotics. The bioactive compounds which are responsible for that action are fatty acids including PUFAs, polysaccharides, glycosides, peptides, neophytadiene, etc. Cyanobacteria, such as Arthrospira, also particularly have antimicrobial flavonoids, terpenes, alkaloids, saponins, quinones and some unique-to-them compounds, such as phycobiliproteins, polyhydroxybutyrate, the peptide microcystin, etc. These metabolites can be optimized by using stress factors in a two-step process of fermentation in closed photobioreactors (PBRs). Full article

Algae-driven processes, such as direct CO₂ fixation into glycerol, provide new routes for sustainable chemical production in synergy with greenhouse gas mitigation. The marine microalgae Dunaliella tertiolecta is reported to accumulate high amounts of intracellular glycerol upon exposure to high salt concentrations. We have conducted a comprehensive, time-resolved systems biology study to decipher the metabolic response of D. tertiolecta up to 24 h under continuous light conditions. Initially, due to a lack of reference sequences required for MS/MS-based protein identification, a high-quality draft genome of D. tertiolecta was generated. Subsequently, a database was designed by combining the genome with transcriptome data obtained before and after salt stress. This database allowed for detection of differentially expressed proteins and identification of phosphorylated proteins, which are involved in the short- and long-term adaptation to salt stress, respectively. Specifically, in the rapid salt adaptation response, proteins linked to the Ca²⁺ signaling pathway and ion channel proteins were significantly increased. While phosphorylation is key in maintaining ion homeostasis during the rapid adaptation to salt stress, phosphofructokinase is required for long-term adaption. Lacking β-carotene, synthesis under salt stress conditions might be substituted by the redox-sensitive protein CP12. Furthermore, salt stress induces upregulation of Calvin–Benson cycle-related proteins. Full article

Sea urchins play an important role in coastal marine ecosystems and are an economically valuable resource for their gonads (roe or uni). Increased demand by Asian and European countries caused overfishing of wild stocks resulting in a sharp decline of sea urchin populations. The increased efforts in developing cost-effective protocols are focused on larval development up to pre- and post-metamorphosis stages, as they are one of the main difficulties of echinoculture. This is a preliminary study to evaluate the influence of microalgal varying diet rationing on larval development, growth, and survivorship at pre-metamorphosis of Sphaerechinus granularis echinopluteus (30 days post-fertilization). Three microalgae diets based on Dunaliella tertiolecta and Rhodomonas marina and the combination of both species were tested. Each diet used three ration treatments: low ration (500–3000 cells⋅ml⁻¹); medium ration (1000–6000 cells⋅ml⁻¹); and high ration (4000–24,000 cells⋅ml⁻¹), which were cell-density adjusted to larval development. Assays used three triplicated treatments in 8 L cylindrical–conical glass incubators. Results showed that the survival of S. granularis echinopluteus was positively influenced by diets of lower cellular densities and a combined microalgae diet. Adoption of this type of diet regime is expected to improve larval production and provide the groundwork for future research on S. granularis in aquaculture. Full article

Atomic force microscopy (AFM) is a method that provides the nanometer-resolution three-dimensional imaging of living cells in their native state in their natural physiological environment. In addition, AFM’s sensitivity to measure interaction forces in the piconewton range enables researchers to probe surface properties, such as elasticity, viscoelasticity, hydrophobicity and adhesion. Despite the growing number of applications of AFM as a method to study biological systems, AFM is not yet an established technique for studying microalgae. Following a brief introduction to the basic principles and operation modes of AFM, this review highlights the major contributions of AFM in the field of microalgae research. A pioneering AFM study on microalgae was performed on diatoms, revealing the fine structural details of diatom frustule, without the need for sample modification. While, to date, diatoms are the most studied class of microalgae using AFM, it has also been used to study microalgae belonging to other classes. Besides using AFM for the morphological characterization of microalgae at the single cell level, AFM has also been used to study the surface properties of microalgal cells, with cell elasticity being most frequently studied one. Here, we also present our preliminary results on the viscoelastic properties of microalgae cell (Dunaliella tertiolecta), as the first microrheological study of microalgae. Overall, the studies presented show that AFM, with its multiparametric characterization, alone or in combination with other complementary techniques, can address many outstanding questions in the field of microalgae. Full article

Antifouling substances play a crucial role in inhibiting fouling and adhesion due to their broad-spectrum and non-toxic advantages. Nevertheless, the excessive release of the antifouling agents shortens the service life of the antifouling coating. In this study, we investigated the antifouling performance of an ethanol extract from the root of Stellera chamaejasme (Sc) through algal adhesion experiments. The interaction between Sc and algae (Chlorella and Dunaliella tertiolecta) was further studied by using a UV spectrophotometer. Then, Sc was encapsulated with polydopamine (PDA) microcapsules to prepare Sc@SiO₂@PDA microcapsules by the template method. The release behavior of Sc@SiO₂@PDA under different pH conditions was investigated. The result demonstrates that the interaction between Sc and algae belongs to single static quenching, and the Sc@SiO₂@PDA microcapsules exhibit good antifouling performance against Chlorella and Dunaliella tertiolecta. This work will provide guiding significance for the development of eco-friendly marine antifouling coatings. Full article

Biodiesel is being considered a possible alternative fuel due to its similarity with diesel and environmental benefits. This current work involves a numerical investigation of CI engine characteristics operating on D100 (diesel) and Dunaliella tertiolecta (DMB20), Scenedesmus obliquus (SOMB20), Scenedesmus dimorphu (SDMB20), and Chlorella protothecoides (CMB20) microalgae biodiesel blend. A diesel engine of 3.7 kW was used with variable compression ratios (CRs) (15.5, 16.5, 17.5, and 18.5) and constant speed (1500 rpm). Comparative analysis was performed for engine characteristics, including emission, combustion, and performance. Cylinder pressure, heat release rate, brake thermal efficiency, specific fuel consumption, particulate matter, oxide of nitrogen, carbon dioxide, etc., were evaluated using the blended fuel. The results show that the maximum cylinder pressure falls, SFC increases, and EGT and BTE were reduced for all blends at full load. In terms of emission characteristics, PM and smoke were lowered when compared to diesel, but a slight increment in NOx and CO₂ was observed. Among all the blends, SOMB20 shows the most decrement in PM and smoke emissions by 14.16% and 11.6%, respectively, at CR 16.5. CMB20 shows a maximum increment in SFC by 3.22% at CR 17.5. A minimum reduction in CP and HRR was shown by DMB20 irrespective of CRs. Full article

The photocatalytic degradation of Acid Red 26 was examined utilizing a graphitic carbon nitride (g-C₃N₄) catalyst and a UV-A light in this study. We investigated how successfully the photocatalytic approach removed Acid Red 26 from synthetic and actual municipal wastewater. Both aqueous matrices allowed for extremely high clearance rates. Wastewater degraded at a slower rate than the other matrices, this might be ascribed to the wastewater’s complicated chemical composition. Using a liquid chromatography-mass spectrometry (LC-MS), the IPs in both synthetic and actual municipal effluent were determined. The photocatalytic degradation mechanisms of Acid Red 26 are hypothesised to comprise oxidation, dealkylation, and methoxy group cleavage based on the observed intermediate products (IPs). Using proven scavengers, we were also able to investigate the role of reactive species in the degradation process and illustrate the significance of h⁺ and O₂^• in the reaction. Chlorococcum sp. and Dunaliella tertiolecta microalgae were also utilised to assess the development of ecotoxicity. We observed low toxicity throughout the process when clean water was used as the matrix, with no production of hazardous IPs. In the case of actual municipal wastewater, there was an early rise in toxicity, which scientists believe was caused by the matrix’s chemical make-up. To lower the toxicity, a heterogeneous photocatalysis was used, and at the end of the treatment, nearly full detoxification was obtained. Full article

In the present study, the photocatalytic degradation of amisulpride using g-C₃N₄ catalyst under UV-A irradiation was investigated. The photocatalytic process was evaluated in terms of its effectiveness to remove amisulpride from ultrapure and real municipal wastewater. High removal percentages were achieved in both aqueous matrices. However, a slower degradation rate was observed using wastewater as matrix that could be attributed to its complex chemical composition. The transformation products (TPs) were identified with liquid chromatography–mass spectrometry (LC–MS) in both ultrapure and real municipal wastewater. Based on the identified TPs, the photocatalytic degradation pathways of amisulpride are proposed which include mainly oxidation, dealkylation, and cleavage of the methoxy group. Moreover, the contribution of reactive species to the degradation mechanism was studied using well-documented scavengers, and the significant role of h⁺ and O₂^•− in the reaction mechanism was proved. The evolution of ecotoxicity was also estimated using microalgae Chlorococcum sp. and Dunaliella tertiolecta. Low toxicity was observed during the overall process without the formation of toxic TPs when ultrapure water was used as matrix. In the case of real municipal wastewater, an increased toxicity was observed at the beginning of the process which is attributed to the composition of the matrix. The application of heterogeneous photocatalysis reduced the toxicity, and almost complete detoxification was achieved at the end of the process. Our results are in accordance with literature data that reported that heterogeneous photocatalysis is effective for the removal of amisulpride from aqueous matrices. Full article