Search Results (84)

This study investigated the cecal distribution of lipophilic pigments (carotenoids and chlorophylls) from Scenedesmus obliquus and their effects on the activity of the intestinal microbiota in rats. Oleoresins containing different concentrations of microalgal pigments (from 0 to 600 µg·kg⁻¹bw·d⁻¹), previously characterized by chromatographic and spectrometric analyses, were administered for four weeks. At the end of the intervention, cecal content samples were collected and analyzed for their pigment composition, short-chain fatty acids (SCFAs), and probiotic microbiota. Nine pigments were identified in the cecal samples, with all-trans-zeaxanthin and pheophytin being the most abundant in all groups. Furthermore, 15-cis-lutein, all-trans-β-cryptoxanthin, and 9-cis-β-carotene—found exclusively in microalgal oleoresin—were detected only in animals receiving doses above 300 µg·kg⁻¹bw.day⁻¹, indicating a link with the SCFA modulation. These supplementations significantly increased the levels of acetate (300 and 450 µg·kg⁻¹bw·d⁻¹ −13% and 14%), butyrate (300 µg kg⁻¹bw·d⁻¹ −19%), and propionate (600 µg·kg⁻¹bw·d⁻¹ −16%). Notably, 300 µg·kg⁻¹bw·d⁻¹ significantly increased Bifidobacterium and Lactobacillus populations. Overall, the pigment supplementation positively influenced the gut microbiota composition and SCFA production in a dose-dependent manner, particularly at 300 µg·kg⁻¹bw·d⁻¹. These results support the potential application of microalgal pigments as functional food ingredients or supplements with gut health benefits. Full article

In this study, cucumber seedlings were treated with Scenedesmus obliquus at different concentrations (0.25, 0.50, 0.75, 1 g·L⁻¹) under saline–alkali stress (60 mM and 90 mM). The effects of Scenedesmus obliquus on the repair of cucumber seedlings under saline–alkali stress were explored from physiological and morphological perspectives by measuring growth physiological indices and observing microstructure. It provides a cytological basis for the development of microalgae biofertilizer. The results showed that the addition of Scenedesmus obliquus effectively alleviated the physiological and structural damage in cucumber seedlings caused by saline–alkali stress, with the best mitigation effect at 0.75 g·L⁻¹. More specifically, the addition of Scenedesmus obliquus significantly improved seedling fresh weight and plant height under saline–alkali stress, increased stem vascular vessel diameter, thickened vessel walls, reduced structural damage, the structural recovery of mitochondria, nuclei, and other organelles in the phloem; The results showed that root xylem vessel distribution became more centralized, vessel diameter decreased, and wall thickness decreased, with other changes similar to those in the stem; The number and volume of mesophyll cells increased, chloroplast morphology recovered, and chlorophyll content rose, effectively alleviating the impact of saline–alkali stress on photosynthesis. MDA content decreased, mitigating oxidative damage caused by saline–alkali stress. Full article

Polyamines play a pivotal role in regulating the growth and metabolic adaptation of microalgae, yet their integrative regulatory roles remain underexplored. This review advances a comprehensive perspective of microalgae growth, integrating polyamine dynamics, amino acid metabolism, and redox balance. Polyamines (putrescine, spermidine, and spermine) biology in microalgae, particularly Chlamydomonas reinhardtii, is reviewed, exploring their critical function in modulating cell cycle progression, enzymatic activity, and stress responses through nucleic acid stabilization, protein synthesis regulation, and post-translational modifications. This review explores how the exogenous supplementation of polyamines modifies their intracellular dynamics, affecting growth phases and metabolic transitions, highlighting the complex regulation of internal pools of these molecules. Comparative analyses with Chlorella ohadii and Scenedesmus obliquus indicated species-specific responses to polyamine fluctuations, linking putrescine and spermine levels to important tunable metabolic shifts and fast growth phenotypes in phototrophic conditions. The integration of multi-omic approaches and computational modeling has already provided novel insights into polyamine-mediated growth regulation, highlighting their potential in optimizing microalgae biomass production for biotechnological applications. In addition, genomic-based modeling approaches have revealed target genes and cellular compartments as bottlenecks for the enhancement of microalgae growth, including mitochondria and transporters. System-based analyses have evidenced the overlap of the polyamines biosynthetic pathway with amino acids (especially arginine) metabolism and Nitric Oxide (NO) generation. Further association of the H₂O₂ production with polyamines metabolism reveals novel insights into microalgae growth, combining the role of the H₂O₂/NO rate regulation with the appropriate balance of the mitochondria and chloroplast functionality. System-level analysis of cell growth metabolism would, therefore, be beneficial to the understanding of the regulatory networks governing this phenotype, fostering metabolic engineering strategies to enhance growth, stress resilience, and lipid accumulation in microalgae. This review consolidates current knowledge and proposes future research directions to unravel the complex interplay of polyamines in microalgal physiology, opening new paths for the optimization of biomass production and biotechnological applications. Full article

Phosphorus contamination in water bodies is a major contributor to eutrophication, leading to algal overgrowth, oxygen depletion, and ecological imbalance. Conventional treatment methods, including chemical precipitation and synthetic adsorbents, are often limited by high operational costs, low biodegradability, and secondary pollutant generation. In this study, a cationic starch was synthesized through free radical graft polymerization of 3-methacrylamoylaminopropyl trimethyl ammonium chloride (MAPTAC) onto corn starch. The modified polymer exhibited a high degree of substitution (DS = 1.24), indicating successful functionalization with quaternary ammonium groups. Theoretical calculations using zDensity Functional Theory (DFT) at the B3LYP/6-311+G(d,p) level revealed a decrease in chemical hardness (from 0.10442 eV to 0.04386 eV) and a lower ionization potential (from 0.24911 eV to 0.15611 eV) in the modified starch, indicating enhanced electronic reactivity. HOMO-LUMO analysis and molecular electrostatic potential (MEP) maps confirmed increased electron-accepting capacity and the formation of new electrophilic sites. Experimentally, the cationic starch showed stable zeta potential values averaging +15.3 mV across pH 5.0–10.0, outperforming aluminum sulfate (Alum), which reversed its charge above pH 7.5. In coagulation-flocculation trials, the modified starch achieved 87% total suspended solids (TSS) removal at a low coagulant-to-biomass ratio of 0.0601 (w/w) using Scenedesmus obliquus, and 78% TSS removal in real wastewater at a 1.5:1 ratio. Additionally, it removed 30% of total phosphorus (TP) under environmentally benign conditions, comparable to Alum but with lower chemical input. The integration of computational and experimental approaches demonstrates that MAPTAC-modified starch is an efficient, eco-friendly, and low-cost alternative for nutrient and solids removal in wastewater treatment. Full article

Wastewater (WW) treatment using biofilms harboring bacteria and microalgae is considered a promising polishing solution to improve current treatment technologies present in wastewater treatment plants (WWTPs), but their interaction in a sessile community remains to be understood. In this work, multi-species biofilms of Chlorella vulgaris, Chlorella sorokiniana, or Scenedesmus obliquus were selected as representative microalgae species of interest for WW bioremediation, and Rhodococcus fascians, Acinetobacter calcoaceticus, or Leucobacter sp. were selected as the bacteria for co-cultivation in a synthetic WW since they are normally found in WW treatment processes. The attached consortia were developed in specific carriers (K5 carriers) for 168 h, and their biofilm formation ability was evaluated in a profilometer and via scanning electron microscopy (SEM) imaging. From the selected microorganisms, C. sorokiniana was the microalga that adapted best to co-cultivation with R. fascians and A. calcoaceticus, developing a thicker biofilm in these two consortia (3.44 ± 0.5 and 4.51 ± 0.8 µm, respectively) in comparison to the respective axenic cultures (2.55 ± 0.7 µm). In contrast, Leucobacter sp. did not promote biofilm growth in association with C. vulgaris and C. sorokiniana, while S. obliquus was not disturbed by the presence of this bacterium. Some bacterial clusters were observed through SEM, especially in A. calcoaceticus cultures in the presence of microalgae. In some combinations (especially when C. vulgaris was co-cultivated with bacteria), the presence of bacteria was able to increase the number of microalga cells adhered to the K5 carrier. This study shows that biofilm development was distinctly dependent on the co-cultivated species, where synergy in biofilm formation was highly dependent on the microalgae and bacteria species. Moreover, profilometry appears to be a promising method for biofilm analyses. Full article

Microalgal biotechnology is gaining attention due to its potential to produce pigments, lipids, biofuels, and value-added products. However, challenges persist in terms of the economic viability of microalgal lipid production in photobioreactors due to slow growth rates, expensive media, complex downstream processing, limited product yields, and contamination risks. Recent studies suggest that co-cultivating microalgae with bacteria can enhance the profitability of microalgal bioprocesses. Immobilizing bacteria offers advantages such as protection against shear forces, the prevention of overgrowth, and continuous product secretion. Previous work has shown that biopolymeric immobilization of Paenibacillus polymyxa enhances 2,3-butanediol production. In this study, a novel co-fermentation process was developed by exploiting the chemical crosstalk between a freshwater microalga Scenedesmus obliquus, also known as Tetradesmus obliquus, and an immobilized plant-growth-promoting bacterium, Paenibacillus polymyxa. This co-cultivation resulted in increased metabolite production, with a 1.5-fold increase in the bacterial 2,3-butanediol concentration and a 3-fold increase in the microalgal growth rates compared to these values in free-cell co-cultivation. Moreover, the co-culture with the immobilized bacterium exhibited a 5-fold increase in the photosynthetic pigments and a 3-fold increase in the microalgal lipid concentration compared to these values in free-cell co-cultivation. A fixed bed photobioreactor was further constructed, and the co-cultivation bioprocess was implemented to improve the bacterial 2,3-butanediol and microalgal lipid production. In conclusion, this study provides conclusive evidence for the potential of co-cultivation and biopolymeric immobilization techniques to enhance 2,3-butanediol and lipid production. Full article

The expansion of the sugar industry has resulted in large amounts of untreated effluent, necessitating the development of energy-efficient treatment technologies, like microbial desalination cells (MDCs). However, the high cost and potential toxicity of chemical cathode catalysts limit MDC performance, making biocathodes a promising alternative. This study investigates the efficiency of a Scenedesmus obliquus-inoculated photosynthetic microbial desalination cell (PMDC) in the cathode chamber to treat sugar industry effluent, desalinate water, and generate electricity. The performance of the PMDC is compared to that of traditional MDCs. The results showed that the PMDC achieved 21.6% desalination, 73.8% anode COD removal, and a maximum power density of 6.8 mW/m², outperforming MDC by 6.43%, 18.5%, and 112.5%, respectively. These results demonstrate that the PMDC offers an effective, energy-efficient alternative to MDCs with added benefits of nutrient removal and algal biomass production at the cathode, making it a promising solution for water and wastewater treatment. Full article

This study aimed to develop and characterize biodegradable films made from pectin, pomegranate seed oil, and different microalgae (Spirulina platensis, Chlorella sp., and Scenedesmus obliquus) and to evaluate their applicability as packaging by verifying their effect on the conservation and postharvest quality of cajarana (Spondias dulcis). The films proposed in this study were assessed for their physical, optical, and mechanical attributes, as well as the physicochemical characteristics of the fruits coated with the films after 14 days of storage at 10 ± 1 °C and relative humidity of 60 ± 5%. Incorporating microalgae improved the homogeneity and mechanical properties, decreasing breaking stress, elastic modulus, and maximum tensile strength, contributing to a lower solubility and improving the barrier properties of the films compared to the control (T1). The film formulated with 6% citric pectin, 40% glycerin, 0.5 mL·L⁻¹ pomegranate seed oil (PSO), and 0.05% Scenedesmus obliquus showed better performance in solubility, water vapor permeability (WVP), and mechanical properties, maintaining gloss and transparency, approaching the performance of the commercial PVC film. The film was formulated with 6% pectin + 40% glycerin + 0.5 mL·L⁻¹ PSO + 0.05% Chlorella sp. maintained the postharvest quality of cajarana fruits, allowing the conservation of the physicochemical quality of the fruits after 14 days of storage at 10 ± 1 °C and 60 ± 5% RH. Full article

Cutaneous melanoma (CM) is an aggressive and metastatic tumor, resulting in high mortality rates. Despite significant advances in therapeutics, the available treatments still require improvements. Thus, purinergic signaling emerged as a potential pathway to cancer therapy due to its involvement in cell communication, proliferation, differentiation, and apoptosis. In addition, due to safety and acceptable clinical tolerability, carotenoids from microalgae have been investigated as adjuvants in anti-melanoma therapy. Then, this work aimed to investigate the in vitro anti-melanogenic effect of carotenoid extract (CA) and total biomass (BM) of the Scenedesmus obliquus microalgae on two cutaneous melanoma cell lines (A375 and B16F10). Cells were cultivated under ideal conditions and treated with 10, 25, 50, and 100 μM of CA or BM for 24 h. The effects of the compounds on viability, oxidant status, and purinergic signaling were verified. The IC50 cell viability results showed that CA and BM decreased B16F10 viability at 24.29 μM and 74.85 μM, respectively and decreased A375 viability at 73.93 μM and 127.80 μM, respectively. Carotenoid treatment for 24 h in B16F10 and A375 cells increased the release of reactive oxygen species compared to the control. In addition, CA and BM isolated or combined with cisplatin chemotherapy (CIS) modulated the purinergic system in B16F10 and A375 cell lines through P2X7, A2AR, CD39, and 5′-nucleotidase. They led to cell apoptosis and immunoregulation by activating A2A receptors and CD73 inhibition. The results disclose that CA and BM from Scenedesmus obliquus exhibit an anti-melanogenic effect, inhibiting melanoma cell growth. Full article

Fly ash derived from the incineration of garbage is known to contain hazardous materials that can affect the growth of plants and animals and pose a threat to human health. In this study, we explored how treatment of fly ash leachate with microalgae could alter the properties of dissolved organic matter (DOM). Fly ash leachate samples obtained from a landfill site in Wenzhou were treated with the microalgae Chlorella vulgaris or Scenedesmus obliquus without and with the addition of ammonium ferric citrate (C₆H₈FeNO₇) for 24 days, and changes in DOM levels and types were measured using excitation emission matrix fluorescence technology. The following results were obtained: Analysis of three-dimensional fluorescence spectral indices indicated that the algal treatment process consistently generated new autogenous DOM, with most of the organic matter being newly formed. Additional nutrients had a minor effect on the production and composition of DOM in the system. Using a parallel factor model to analyze the three-dimensional fluorescence spectral matrices of water samples from various systems revealed common components in each group, including arginine, tryptophan-like proteins and fulvic acid-like substances. This study aimed to explore the changes in DOM properties during microalgae treatment of fly ash leachate from the perspective of three-dimensional fluorescence. Full article

The effects of toxic and non-toxic Microcystis aeruginosa on the Ceratophyllum demersum–Scenedesmus obliquus system were simulated in the laboratory, and some parameters in relation to these organisms were measured. In this experiment, C. demersum increased the biomass of S. obliquus, and both toxic and non-toxic M. aeruginosa significantly inhibited the colony formation of S. obliquus and inhibited the promotion of S. obliquus biomass. On the 14th day, the soluble polysaccharide content of C. demersum decreased when it was coexisted with S. obliquus, but it rose again because of M. aeruginosa, which significantly increased the protein content of C. demersum. The species composition and diversity of epiphytic microorganisms also vary with different treatments. Proteobacteria is dominant in all the groups, especially in the Toxic_SMC group. In addition, bacteria that can degrade organic pollutants are more abundant in Toxic_SMC group. This study focuses on the defense response of S. obliquus induced by C. demersum under the pressure of toxic or non-toxic M. aeruginosa and evaluates the changes to C. demersum and its epiphytic microorganisms, which provides insights for the study of aquatic plant–algae integrated action systems in eutrophic or cyanobacterial blooms. Full article

In order to explore the feasibility of using algae to treat the fly ash leachate from a safe landfill site, leachate samples taken from a certain safe landfill site in Wenzhou City were treated with two different microalgae, Chlorella vulgaris and Scenedesmus obliquus, and the effectiveness of each treatment was evaluated in terms of its efficiency of pollutant removal. The effects of conditions such as pretreatment of leachate by sterilization, the initial concentration of leachate, and the addition of nutrients on pollutant removal efficiency and algae growth were studied. Sterilization of the leachate was found to have a relatively small impact on the growth of C. vulgaris and S. obliquus, as well as the removal of pollutants from the leachate. Therefore, sterilization treatment may not be necessary for engineering applications. Algal growth and the removal of pollutants were optimal when the leachate was used at a concentration of 10%, but when the leachate concentration was 30% or higher, the growth of both algae was weakened. The inclusion of 0.2 g/L K₂HPO₄·3H₂O and 0.06 g/L ammonium ferric citrate in the system led to higher algal growth and pollutant removal. The chlorophyll a levels of C. vulgaris and S. obliquus were 555.53% and 265.15%, respectively, and the nitrogen removal rates were also the highest, reaching 59.51% and 56.69%, respectively. This study optimized the cultivation conditions of a microalgae treatment leachate system, providing technical support and a theoretical basis for the practical engineering of a harmless treatment of leachate. Full article

The cultivation of microalgae from municipal wastewater, while simultaneously removing nutrients from the water column, has the potential to aid biodiesel production and carbon dioxide fixation, thereby alleviating the pressure of energy shortages. In this research, different ratios of sodium bicarbonate and glucose were used to prepare simulated municipal wastewater. The results demonstrated that microalgae were most effectively treated under one-stage direct treatment conditions. During direct culture, the most effective treatment was observed for IAA-3, which exhibited a dry weight of 1.4363 g/L and a lipid content of 25.05% after stimulation with 0.0005 M NaHCO₃. In contrast, NaHCO₃-2 demonstrated optimal performance during the secondary culture, with a dry weight of 1.6844 g/L and a lipid content of 18.05%. Finally, the economic, social and environmental benefits of direct treatment (IAA-3) and secondary treatment NaHCO₃-2 were analyzed. The benefits of direct treatment were found to be USD 0.50989/L, while those of secondary treatment were USD 0.43172/L. For each tonne of municipal wastewater treated, the carbon sequestration benefits of IAA-3 during direct treatment and NaHCO₃-2 during secondary treatment were USD 0.45645 and USD 0.85725, respectively. Full article

Microalgae-based water treatments for the removal of different types of pollution have been gaining considerable attention during the last few decades. However, information about microalgae potential in the removal of pharmaceuticals and personal care products (PPCPs) and the ecotoxicological outcomes is still limited. Therefore, in this work, we aimed at investigating salicylic acid removal from water by three different microalgae strains, namely Chlorella sorokiniana, Chlorella vulgaris and Scenedesmus obliquus. For such a purpose, photobioreactors were operated under batch and semi-continuous mode. Apart from determining the reduction in the concentration of salicylic acid attained by each strain, we used zebrafish embryo bioassays to assess the efficiency of microalgae to reduce its toxicity effects. S. obliquus was the strain that achieved the most significant decrease in the concentration and toxic effects of salicylic acid. Indeed, S. obliquus was able to rescue mortality and reduce abnormalities at practically 100%. The efficiency of C. sorokiniana and, especially, that of C. vulgaris were not so remarkable, indicating that the removal of SA and its toxic effects from water by microalgae is markedly strain dependent. The obtained results proved the importance of considering toxic effects for a more comprehensive evaluation of microalgae efficiency in the removal of PPCPs in view of an adequate selection for water treatment. Full article

Chlorella vulgaris and Scenedesmus sp. are commonly used in wastewater treatment due to their fast growth rates and ability to tolerate a range of environmental conditions. This study explored the cultivation of Chlorella vulgaris and Scenedesmus sp. using wastewater from the food industry, particularly from Italian basil pesto production tanks. The experiment involved different carbon dioxide concentrations and light conditions with a dilution rate of basil pesto wastewater at 1:2. Both microalgae strains were able to grow on pesto wastewater, and biomass characterization highlighted the influence of CO₂ supply and light irradiation. The highest lipid storage was 79.3 ± 11.4 mg g_{dry biomass}⁻¹ and 75.5 ± 13.3 mg g_{dry biomass}⁻¹ for C. vulgaris and S. obliquus under red light (5% CO₂ supply) and white light (0.04% CO₂ supply), respectively. Protein storage was detected at 20.3 ± 1.0% and 24.8 ± 1.3% in C. vulgaris and S. obliquus biomasses under white light with a 5% CO₂ and 0.04% CO₂ supply, respectively. The removal of P, N, chemical oxygen demand, and biological oxygen demand resulted in 80–100%, 75–100%, 26–35%, and 0–20%, respectively. Full article