Explore the vast range of titles available.

Carbon nanotubes (CNTs), α-Fe 2 O 3 nanoparticles (nano Fe 2 O 3 ) and MgO nanoparticles (nano MgO) were evaluated for the effects on algae growth and lipid production. Nano Fe 2 O 3 promoted cell growth in the range of 0–20 mg·L −1 . CNTs, nano Fe 2 O 3 and nano MgO inhibited cell growth of Scenedesmus obliquus at 10, 40 and 0.8 mg·L −1 respectively. Neutral lipid and total lipid content increased with the increasing concentration of all tested nanoparticles. The maximum lipid productivity of cultures exposed to CNTs, nano Fe 2 O 3 and nano MgO was observed at 5 mg·L −1 , 5 mg·L −1 and 40 mg·L −1 , with the improvement by 8.9%, 39.6% and 18.5%. High dose exposure to nanoparticles limited increase in lipid productivity, possibly due to the repression on cell growth caused by nanoparticles-catalyzed reactive oxygen species (ROS) generation, finally leading to reduction in biomass and lipid production. Reduced accumulation of fatty acids of C18:3n3, C18:3n6 and C20:2 was observed in cells exposed to nanoparticles.

Biodiesel from microalgae seems to be the only renewable biofuel that has the potential to completely replace the petroleum-derived transport fuels. Therefore, improving lipid content of microalgal strains could be a cost-effective second generation feedstock for biodiesel production. Lipid accumulation in Scenedesmus obliquus was studied under various culture conditions. The most significant increase in lipid reached 43% of dry cell weight (dcw), which was recorded under N-deficiency (against 12.7% under control condition). Under P-deficiency and thiosulphate supplementation the lipid content also increased up to 30% (dcw). Application of response surface methodology in combination with central composite rotary design (CCRD) resulted in a lipid yield of 61.3% (against 58.3% obtained experimentally) at 0.04, 0.03, and 1.0 g l⁻¹ of nitrate, phosphate, and sodium thiosulphate, respectively for time culture of 8 days. Scenedesmus cells pre-grown in glucose (1.5%)-supplemented N 11 medium when subjected to the above optimized condition, the lipid accumulation was boosted up to 2.16 g l⁻¹, the value ~40-fold higher with respect to the control condition. The presence of palmitate and oleate as the major constituents makes S. obliquus biomass a suitable feedstock for biodiesel production.

Small-scale photobioreactors (PBRs) in the inoculum stage were designed with internal (red or green) and external white LED light as an initial step of a larger-scale installation aimed at fulfilling the integral biorefinery concept for maximum utilization of microalgal biomass in a multifunctional laboratory. The specific growth rate of Scenedesmus obliquus (Turpin) Kützing biomass for given cultural conditions was analyzed by using MAPLE software. For the determination of total polyphenols, flavonoids, chlorophyll “a” and “b”, carotenoids and lipids, UHPLC-HRMS, ISO-20776/1, ISO-10993-5 and CUPRAC tests were carried out. Under red light growing, a higher content of polyphenols was found, while the green light favoured the flavonoid accumulation in the biomass. Chlorophylls, carotenoids and lipids were in the same order of magnitude in both samples. The dichloromethane extracts obtained from the biomass of each PBR synergistically potentiated at low concentrations (0.01–0.05 mg/mL) the antibacterial activity of penicillin, fluoroquinolones or oregano essential oil against the selected food-borne pathogens (Staphylococcus aureus, Escherichia coli and Salmonella typhimurium) without showing any in vitro cytotoxicity. Both extracts exhibited good cupric ion-reducing antioxidant capacity at concentrations above 0.042–0.08 mg/mL. The UHPLC-HRMS analysis revealed that both extracts contained long chain fatty acids and carotenoids thus explaining their antibacterial and antioxidant potential. The applied engineering approach showed a great potential to modify microalgae metabolism for the synthesis of target compounds by S. obliquus with capacity for the development of health-promoting nutraceuticals for poultry farming.

In this paper, the influence of culture conditions (irradiance, temperature, pH, and dissolved oxygen) on the photosynthesis rate of Scenedesmus almeriensis cultures is analyzed. Short-run experiments were performed to study cell response to variations in culture conditions, which take place in changing environments such as outdoor photobioreactors. Experiments were performed by subjecting diluted samples of cells to different levels of irradiance, temperature, pH, and dissolved oxygen concentration. Results demonstrate the existence of photoinhibition phenomena at irradiances higher than 1,000 μE/m 2  s; in addition to reduced photosynthesis rates at inadequate temperatures or pH—the optimal values being 35 °C and 8, respectively. Moreover, photosynthesis rate reduction at dissolved oxygen concentrations above 20 mg/l is demonstrated. Data have been used to develop an integrated model based on considering the simultaneous influence of irradiance, temperature, pH, and dissolved oxygen. The model fits the experimental results in the range of culture conditions tested, and it was validated using data obtained by the simultaneous variation of two of the modified variables. Furthermore, the model fits experimental results obtained from an outdoor culture of S. almeriensis performed in an open raceway reactor. Results demonstrate that photosynthetic efficiency is modified as a function of culture conditions, and can be used to determine the proximity of culture conditions to optimal values. Optimal conditions found ( T  = 35 °C, pH = 8, dissolved oxygen concentration <20 mg/l) allows to maximize the use of light by the cells. The developed model is a powerful tool for the optimal design and management of microalgae-based processes, especially outdoors, where the cultures are subject to daily culture condition variations.

Phosphorus is one of the crucial elements required for the proper functioning of metabolic processes in microalgae. Despite the crucial role of phosphate (P), the dynamics of polyphosphate accumulation with respect to nutrient availability remain unknown in freshwater microalgae. We have investigated three freshwater microalgal strains – Chlorella pyrenoidosa , Scenedesmus obliquus , and Chlamydomonas reinhardtii under varied phosphate treatments to understand the phosphate metabolic responses and polyphosphate dynamics. Our results show that the accumulation of polyP in microalgae is very dynamic and mainly depends on the availability of extracellular phosphate. Reduced P availability showed algal species-specific reduction in the polyphosphate storage with a decline in growth and total chlorophyll content. Further, an increase in lipid and carbohydrate content with a substantial decrease in protein was observed under P stress, suggesting preferential utilization of stored polyP to support cell survival. Species-specific differences in the fatty acid profiles were also observed in the GC analysis among all three algal strains, indicating varied mechanisms happening among the species to adapt and protect themselves against cellular damage under P stress. Our results suggest the existence of natural variability among the selected algal strains in their ability to accumulate polyP and metabolites with respect to P-varied conditions. Among the three microalgal species, Scenedesmus obliquus showed notably enhanced accumulation of polyphosphate, highlighting its potential application as P-rich biofertilizer.

The main goals of this study were to produce biodiesel from Scenedesmus obliquus algae using n-butanol as a green fuel and to analyse engine performance, combustion characteristics, and emission. Researchers are looking into how N-butanol affects mixes of Scenedesmus obliquus algae used to make biodiesel for use in Common Rail Direct Injection (CRDI) engines. In the studies, different combinations of Scenedesmus obliquus diesel algae were employed: 30 A (Algae), 30 A + 10% N-Butanol, 30 A + 20% N-Butanol, and 30 A + 30% N-Butanol. The pure 100% Diesel (D100) combination was also used. The butanol blends 30 A + 30% N and 30 A + 10% N both exhibit mediocre performance across the board in terms of emissions and combustion. When compared to pure diesel (D100), the ideal addition was 30 A + 20% N - Butanol, which led to a 10.96% gain in brake thermal efficiency and a 7.4% decrease in specific fuel consumption. On the other hand, because of the high concentration of D100 and the noticeable rise in exhaust temperature, there was an increase in nitrogen oxides in the exhaust gases. On the other hand, the exhaust gases concentrations of carbon monoxide and smoke opacity decreased by 19.2%, and 15%, respectively, in contrast to D100. Hydrocarbon emissions, on the other hand, dropped by 8%. The cylinder pressure and heat release rate improved by 8.6% and 36.43%, respectively, according to the combustion characteristic analysis results.

To investigate the effect of bisphenol A (BPA) on Cylindrospermopsis raciborskii (Cyanobacteria) and Scenedesmus quadricauda (Chlorophyta), we grew the two species at BPA concentrations of 0, 0.1, 1, 2, 5, 10, and 20 mg/L and examined their growth, lipid peroxidation, antioxidant enzyme activity, and chlorophyll a fluorescence. The 96-h EC50 values (effective concentration causing 50% growth inhibition) for BPA in C. raciborskii and S. quadricauda were 9.663 ± 0.047, and 13.233 ± 0.069 mg/L, respectively. A significant reduction in chlorophyll a concentration was found in C. raciborskii and S. quadricauda when BPA concentrations were greater than 1 and 2 mg/L, respectively. Furthermore, Fv/Fm, ΔF/Fm′, and qP decreased significantly at 10 mg/L BPA in C. raciborskii but started to decrease at 10 mg/L in S. quadricauda. The changes in chlorophyll fluorescence parameters (α, rETRmax) that were obtained from the rapid light response curves of both algae species showed similar responses to Fv/Fm, ΔF/Fm′, and qP under BPA-induced stress. Values for all of the chlorophyll fluorescence parameters in S. quadricauda were higher than in C. raciborskii; however, the nonphotochemical quenching measured in C. raciborskii was considerably higher than it was in S. quadricauda. In addition, lipid peroxidation (determined as MDA content) and antioxidant enzyme activities (SOD and CAT) increased in both species as the BPA concentration increased. These results suggest that C. raciborskii is more sensitive to the effects of BPA than S. quadricauda and that photosystem II might be a target for the activity of BPA in vivo.

Scenedesmus sp. is a species of the Scenedesmus genus within the phylum Chlorophyta, commonly found as a planktonic algal species in freshwater and known for its rapid growth rate. This study employs room-temperature, atmospheric-pressure plasma mutagenesis for the breeding of Scenedesmus sp., utilizing transcriptomic analysis to investigate the biosynthesis mechanism of triglycerides. Further analysis of differentially expressed genes in transcriptome by measuring the macroscopic biological indicators of mutant and original algal strains. The findings of the study suggest that the mutant strain's photosynthesis has been enhanced, leading to improved light energy utilization and CO 2 fixation, thereby providing more carbon storage and energy for biomass and lipid production. The intensification of glycolysis and the TCA (tricarboxylic acid) cycle results in a greater shift in carbon flux towards lipid accumulation. An elevated expression level of related enzymes in starch and protein degradation pathways may enhance acetyl CoA accumulation, facilitating a larger substrate supply for fatty acid production and thereby increasing lipid yield.

Scenedesmus spp. have been reported as potential microalgal species used for the lipid production. This study investigated the effects of light intensity (at three levels: 50, 250, and 400 μmol photons m −2  s −1 ) on the growth and lipid production of Scenedesmus sp. 11-1 under N-limited condition. Carotenoid to chlorophyll ratio was higher when algae 11-1 grew under 250 and 400 μmol photons m −2  s −1 than that under 50 μmol photons m −2  s −1 , while protein contents was lower. Highest biomass yield (3.88 g L −1 ), lipid content (41.1 %), and neutral lipid content (32.9 %) were achieved when algae 11-1 grew at 400 μmol photons m −2  s −1 . Lipid production was slight lower at 250 μmol photons m −2  s −1 level compared to 400 μmol photons m −2  s −1 . The major fatty acids in the neutral lipid of 11-1 were oleic acid (43–52 %), palmitic acid (24–27 %), and linoleic acid (7–11 %). In addition, polyunsaturated fatty acids had a positive correlation with total lipid production, and monounsaturated fatty acids had a negative one.

Microalgae like Scenedesmus sp. are promising alternatives for sustainable food and animal feed due to their high protein content and adaptability to different light intensities. Optimal light enhances growth and nutrient accumulation, while excessive light can reduce productivity. This study investigates the effects of different light intensities (100–300 µmol m⁻ 2  s⁻ 1 ) on the growth performance and nutritional composition of Scenedesmus sp., aiming to improve microalgae production efficiency and contribute to commercial standards for sustainable protein sources. Results show that dry biomass concentration (0.975 g L −1 ) and cell count (2.96) peaked at a light intensity of 200 μmol m −2  s −1 ( P  <  0.0001 ), while dry biomass decreased at 300 μmol m⁻ 2  s⁻ 1 . Scenedesmus sp. grown at 200 and 300 µmol m −2  s −1 had higher carbohydrate contents (50.1% and 54%, P  <  0.001 ), while the highest lipid content (42.3%) was observed at 100 µmol m −2  s −1 . The highest crude protein was recorded at 200 µmol m −2  s −1 (15.6%, P  <  0.0001 ). Regarding amino acid composition, leucine was the most abundant essential amino acid (1.20 mg/100 mg dry weight), while glutamic acid was the most abundant non-essential amino acid (1.73 mg/100 mg). For color characteristics, biomass produced at 300 µmol m −2  s −1 exhibited a darker color, with the lowest L* value (21.66), and a more yellowish hue compared to 200 µmol m −2  s −1 . These findings highlight the importance of optimizing light conditions to enhance Scenedesmus sp. productivity for sustainable animal feed applications. This study indicates that the productivity of Scenedesmus sp. could be enhanced for biomass and protein production by maintaining an optimal light regime. By maximizing biomass yield and nutrient composition, this study supports the development of microalgae-based protein sources that can serve as a viable alternative to conventional feed ingredients, contributing to more sustainable and efficient feed production systems.