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•The two mutants with contrasting photosynthetic characteristics were screened out.•S-#26 adapted to prolonged high light stress, achieving a 28.34% biomass increase.•DEPs from carbon ...metabolism mainly affect the two mutants’ biomass oppositely.•The contrasting regulation of the TCA cycle proteins was showed in the two mutants.
Microalgae’s superior ability to fix carbon dioxide into biomass and high-value bioproducts remains underutilized in biotechnological applications due to a lack of comprehensive understanding of their carbon metabolism and energy conversion. In this work, the strain improvement technique heavy-ion beams (HIB) mutagenesis was employed on the environmentally adaptable microalgae Scenedesmus quadricauda. After several rounds of screening, two contrasting mutants were identified. S-#4 showed low photosynthetic activity and biomass productivity, while S-#26 exhibited adaptability to prolonged high light stress, achieving a 28.34 % increase in biomass yield compared to the wild-type strain. Integrating their photosynthetic characteristics and comparative proteomic analysis revealed that the contrasting protein regulations from central carbon metabolism mainly affects the two mutants’ opposite biomass accumulation. Therefore, the divergent regulation of the tricarboxylic acid cycle following HIB mutagenesis could be potential targets for engineering microalgae with superior biomass and high-value products.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•R2 values of RSM represents the best fit of model for lipid content.•Nitrate/phosphate ratio is the key component responsible for lipid accumulation.•C16:0, C17:0, C18:0, C16:1, C18:1, C18:2, C18:3 ...were the main FAME constituents.•Scenedesmus quadricauda seems to be potential feedstock for biodiesel production.
Scenedesmus quadricauda isolates were tested for growth kinetics and lipid accumulation capability. Scenedesmus quadricauda revealed greater potential as a biofuel feedstock, based on data gathered on growth parameters and lipid accumulation, as well as RSM and GC–MS tests.
In the present study, Scenedesmus quadricauda was sequenced and documented through the NCBI website before performing phylogenetic analysis with amplified 18S rRNA gene sequences and amplified 18S rRNA gene fragments. RSM was used to determine not only the ideal circumstances, but also the interaction between the nutritional components that impact Scenedesmus quadricauda development. Examination of FAMEs generated by transesterification of lipids taken from Scenedesmus quadricauda using different standardized techniques was also done using GC–MS.
Sequence alignment result revealed that isolated algal strain was exhibiting 100 percent homology with Scenedesmus quadricauda and the sequence data was provided with a NCBI GenBank accession number. Heterotrophic culture of Scenedesmus quadricauda resulted in a greater growth rate and cell productivity, according to RSM. Contour plots are indicating that phosphate and nitrate have gradual increasing effect on lipid but increase in lipid accumulation occurs after little decrease of nitrate concentration (15.0 mM). Interactive effects of pH and nitrate resulted in the inhibitory effect of the both variables at higher level on lipid accumulation. Fatty acids C 16:0, C 17:0, C 18:0, C 16:1, C 18:1, C 18:2 and C 18:3 were identified during GC–MS analysis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the commercial production of microalgae biodiesel, high culture cost and low lipid production yields are two major limitations. Finding cheap carbon sources and ways to promote lipid accumulation ...can achieve low-cost cultivation and efficient lipid production. The impact of NaCl on the growth and lipid accumulation in Scenedesmus quadricauda FACHB-1297 under xylose mixotrophic cultivation was explored in this study. The results showed that when NaCl concentration were 0.88–5.85 g/L, the biomass concentration and lipid content were 2.15–2.68 and 1.19–1.80 times higher than those in BG11 medium, respectively. Under the optimal NaCl concentration of 2.63 g/L, the highest lipid content (39.33%) was achieved, with the biomass concentration of 0.72 g/L, the total nitrogen removal efficiency of 39.00%, and the total phosphorus removal efficiency of nearly 100.00%, except for a higher total sugar content of 19.26% and total protein content of 5.38%. In short, these results indicated that 2.63 g/L NaCl treatment was an efficient way to promote the lipid accumulation of S. quadricauda FACHB-1297 using xylose in papermaking waste liquid to produce biofuel.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
Microalgal biomass is a potential feedstock for biofuel production because of its oleaginous nature and fast growth rate. Furthermore, its cultivation does not compete with crop producing land and ...thereby eliminating food vs. fuel dilemma. This study describes a low-cost nutrient mediated cultivation method for growing lipid enriched algal biomass from Scenedesmus quadricauda in BG11 media in a raceway pond. A renewable heterogeneous catalyst is synthesized using calcium oxide obtained from calcination of waste egg shells and modified using cobalt nitrate hexahydrate by co-precipitation method. The synthesized catalyst is characterized by XRD, SEM, EDX, FTIR, TEM techniques. Lipid extracted from the biomass is converted to biodiesel using the synthesized catalyst. The formation of biodiesel is confirmed using 1H NMR, 13C NMR and GC-MS techniques. The result demonstrated that the CaO–Co catalyst has very high catalytic activity for biodiesel production. The integrated process described in this study has potential for producing environmentally benign fuels and a heterogeneous catalyst from renewable sources.
•The microalgae Scenedesmus quadriacuda is a good candidate for biofuel production.•KNO3 helps in lipid enhancement.•The catalyst CaO-Co is renewable in nature.•The algal biodiesel yield is 98%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The green algae
Scenedesmus quadricauda was immobilized in alginate gel beads. The immobilized active (IASq) and heat inactivated
S.
quadricauda (IHISq) were used for the removal of Remazol Brilliant ...Blue R (CI 61200, Reactive Blue 19, RBBR) from aqueous solutions in the concentration range 25–200
mg
L
−
1
. At 150
mg
L
−
1
initial dye concentration the IASq and IHISq exhibited the highest dye uptake capacity at 30
°C, at the initial pH value of 2.0. At the same initial dye concentration in the batch system the adsorption capacity was determined for IASq as 44.2; 44.9 and 45.7
mg
g
−
1
in 30, 60 and 300
min, respectively. After 300
min the adsorption capacity hardly changed during the adsorption time. The IHISq of adsorption capacity was observed as 47.6; 47.8 and 48.3
mg
g
−
1
in 30, 60 and 300
min, respectively. After 300
min the adsorption capacity was not changed for 24
h. The Langmuir, Freundlich, Temkin, Dubinin–Radushkevich and Flory–Huggins isotherm models were used to fit the equilibrium biosorption data. The Langmuir, Freundlich and Dubinin–Radushkevich equations have better coefficients than Temkin and Flory–Huggins equation describing the RBBR dye adsorption onto IASq and IHISq. The monomolecular biosorption capacity of the biomass was found to be 68 and 95.2
mg
g
−
1
for IASq and IHISq, respectively. From the Dubinin–Radushkevich model, the mean free energy was calculated as 6.42–7.15
kJ
mol
−
1
for IASq and IHISq, indicating that the biosorption of dye was taken place in physical adsorption reactions. The experimental data were also tested in terms of kinetic characteristics and it was determined that the biosorption process of dye was well explained with pseudo-second-order kinetics.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Pyrolysis mechanism and kinetics were investigated for microalgal biomass.•Activation energy profile indicated complex degradation process in pyrolysis zone.•Positive values of ΔH & ΔG indicated ...requirement of external energy source.
Bioenergy potential of microalage Scednedesmus quadricuda through pyrolysis was investigated using kinetic and thermodynamic analyses. From model-free isoconversional methods, the estimated average activation energies were 152.37 (±20.93), 174.98 (±22.38), and 153.00 (±21.23) kJ/mol, using Friedman, OFW and advance Vyazovkin methods, respectively. Avrami-Erofeev’s A1/4 reaction model was the most probable single-step reaction mechanism determined from the combined kinetic analysis. The activation energy profile, however, indicated a complex degradation process in the active pyrolysis zone. Two independent parallel reactions were considered in the active pyrolysis zone. Average activation energy for low temperature conversion was 77.95 (±3.12) kJ/mol, pre-exponential coefficient 4.86E4 (±2.24E4) s−1, and n = 1.51 (±0.10), whereas for high temperature conversion, the activation energy was 73.26 (±17.93) kJ/mol, pre-exponential coefficient 1.32E3 (±2.61E3) s−1, and n = 1.21 (±0.16). Thermodynamic analysis of pyrolysis in terms of enthalpy, Gibbs free energy, and entropy indicated the feasibility of conversion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the present work, the photo-Fenton-like process based on the use of the Fe2.5Co0.3Zn0.2O4/CuCr-LDH composite was applied for the removal of green algal cells. First, the biological activity of the ...composite was proved with the antibacterial tests against the S. aureus; thereafter, it was used for the removal of Scenedesmus quadricauda algal cells under the photo-Fenton-like process. Interestingly, compared with the individual processes, the photo-Fenton-like process displayed a synergistic effect in the deactivation of green algal cells. The effect of various parameters such as the initial concentration of the algal cells, concentration of the hydrogen peroxide (HP), and the solution pH on the total algal. The maximuml was assessed. Maximum algal removal efficiency was obtained in the presence of the algal cell concentration of 3.5 × 109 cells mL−1, 0.1 g L−1 composite, and HP concentration of 10 mM. Furthermore, the microscopic and SEM images of the algal cells before and after the photo-Fenton-like process proved their appropriate destruction. The reduction of the chlorophyll content after 60 and 120 min of the process was observed revealing the destruction of the algal cell walls. Finally, the disintegration of the macromolecules in the algal cell walls was proved by the GC-MS technique.
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•Effective removal of Scenedesmus quadricauda algal cells from contaminated water.•Antibacterial activity of the composite of Fe2.5Co0.3Zn0.2O4 and CuCr-LDH.•Photo-Fenton-like degradation process showed maximum algal removal efficiency.•Microscopic and SEM images showed effective algal cell destructions.•GC-MS analysis revealed the destruction of algal cell walls to small molecules.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Oxidation treatment of algae-laden water may cause cells rupture and emission of intracellular organics, thus restricting its further popularization. As a moderate oxidant, calcium sulfite could be ...slowly released in the liquid phase, thus exhibiting a potential to maintain the cells integrity. To this end, calcium sulfite oxidation activated by ferrous iron was proposed integrated with ultrafiltration (UF) for removal of Microcystis aeruginosa, Chlorella vulgaris and Scenedesmus quadricauda. The organic pollutants were significantly eliminated, and the repulsion between algal cells was obviously weakened. Through fluorescent components extraction and molecular weights distribution analyses, the degradation of fluorescent substances and the generation of micromolecular organics were verified. Moreover, the algal cells were dramatically agglomerated and formed larger flocs under the premise of maintaining high cell integrity. The terminal normalized flux was ascended from 0.048–0.072 to 0.711–0.956, and the fouling resistances were extraordinarily decreased. Due to the distinctive spiny structure and minimal electrostatic repulsion, Scenedesmus quadricauda was easier to form flocs, and its fouling was more readily mitigated. The fouling mechanism was remarkably altered through postponing the formation of cake filtration. The membrane interface characteristics including microstructures and functional groups firmly proved the fouling control efficiency. The reactive oxygen species (i.e., SO4•− and 1O2) generated through the principal reactions and Fe–Ca composite flocs played dominant roles in alleviating membrane fouling. Overall, the proposed pretreatment exhibits a brilliant application potential for enhancing UF in algal removal.
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•CaSO3 activated by Fe(II) was proposed for the removal of various types of algae.•The sustained-release property of CaSO3 helped to maintain the cells integrity.•The formation of complex flocs positively affected the aggregation of algal cells.•The CaSO3/Fe(II) integrated strategy efficiently alleviated membrane fouling.•A mass of oxygen species (i.e., SO4.•− and 1O2) were generated in the process.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Microalgae are a potential source of a wide range of food and novel value‐added products. The versatility of microalgae to produce different kind of pigments is gaining interest as a sustainable ...source of natural carotenoids. Currently, commercial production of carotenoids from selected microalgae requires special culture conditions which are difficult to maintain. The present study has been undertaken to optimize culture conditions for growth and carotenoid production by a new isolate Scenedesmus quadricauda PUMCC 4.1.40. The results revealed that test organism produced 1.54 mg dry biomass/ml with a content of 40 μg carotenoids/mg dry biomass during stationary phase. The growth and carotenoid production was increased by 2.4‐fold under combined optimized culture conditions. The optimized conditions were growth medium, Chu‐10; pH 8.5; temperature, 30°C; nitrogen, 20 mM nitrate; phosphate, 0.22 mM; NaCl, 0.42 mM and blue light. Separation and identification of four important carotenoids through high‐performance thin‐layer chromatography (HPTLC) followed by purification using flash chromatography and quantification by HPLC revealed 23.8, 19.0, 6.5, and 4.0 μg astaxanthin, β‐carotene, lutein, and canthaxanthin /mg dry biomass, respectively. The amount of total carotenoids (98 μg/mg dry biomass) containing 40% valuable astaxanthin and β‐carotene produced under optimized conditions was significantly higher than control cultures. This justifies that S. quadricauda is a promising candidate for scale‐up production of carotenoid.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
