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Bold Basal Medium (BBM) is a standard but expensive medium for Chlorella ellipsoidea culture. This study evaluated the effect of biofloc wastewater (BWW) on the growth and pigment content of C. ellipsoidea and also investigated its bioremediation potential. The experiment was conducted for 24 d in five treatments, each with three replications. BBM was replaced with BWW at 0, 25, 50, 75, and 100% levels and considered as control (0% BWW), 25% BWW, 50% BWW, 75% BWW, and 100% BWW treatment, respectively. During the exponential period, the cell dry weight, optical density, cell density, specific growth rate, chlorophyll a, b, and β-carotene content were significantly (P ˂ 0.05) higher in 75% BWW treatment, which was followed by 0% BWW, 50% BWW, 100% BWW, and 25% BWW, correspondingly. NH3, NO2, and PO4 recovery efficiency were also higher in 75% BWW treatment. Therefore, the study proves that 75% BWW has the potential to culture C. ellipsoidea as an alternative to expensive BBM along with nutrient recovery from BWW. [ABSTRACT FROM AUTHOR]

The influence of elevated CO2 concentrations on the growth and viability of various microalgae strains was studied. Arthrospira platensis, Chlorella ellipsoidea, Chlorella vulgaris, Gloeotila pulchra, and Elliptochloris subsphaerica were tested. The cultivation of microalgae was carried out at constant CO2 concentrations (0.04, 3, 6, or 9%—sequentially from lower to higher concentrations), under constant (24 h·day−1) illumination with an intensity of 74.3 µmol quanta·m−2·s−1, and a constant temperature of 23.5 ± 0.5 °C. The optical density of the microalgae biomass, pH, and the chemical composition of the culture medium were measured. Microscopy (including the cytochemical microscopic method) was conducted to monitor the state of the microalgae. The highest biomass growth rate (0.37 g·L−1·day−1), among all experiments, was achieved for Chlorella vulgaris at CO2 = 3% and for Chlorella ellipsoidea at CO2 = 6 and 9%. The lowest growth rate (0.12 g·L−1·day−1) was achieved for Arthrospira platensis at CO2 = 3 and 9%. The microscopy results showed the absence or a minimum number of dead cells of the strains under selected conditions. The ability to maintain the viability of cultures up to significant concentrations of CO2 = 9% was due to adaptation (gradual increase in CO2 concentrations in the experiments). [ABSTRACT FROM AUTHOR]

The objective of this work was to investigate the potential of pumpkin rind and seed on antidiabetic and anti-inflammatory activities and the underlying mechanism. Therefore, this work was carried out to determine the antidiabetic activity using inhibitory activities of pumpkin rind and seeds extracts on α - glucosidase and the anti-inflammatory activity via inhibitory activity on nitric oxide production. And also, the potential of the pumpkin rind and seeds on culture of Chlorella ellipsoidea was determined. Determination of inhibitory activity on α - glucosidase was performed using α - glucosidase assay, while the Griess assay was employed for the inhibition on Nitric oxide (NO) -production. The pumpkin seed extract inhibited α - glucosidase more potent than the pumpkin rind extract (IC50 of 321.36 vs. 326.18 µg/mL). However, the activities of the extracts were less potent than that of Acarbose (IC50 of 317.26 µg/mL). Application of the extracts at the highest concentration, 500 µg/mL, the pumpkin seed extract displayed the inhibition of NO production higher than the pumpkin rind extract did (18.01 ± 1.57 % vs. 14.99 ± 1.94 %). Study on the effects of pumpkin rind and seeds on C. ellipsoidea culture revealed that the optimum media was the 7th medium (NPK+ mixture of pumpkin seed water and Blue-Green Medium (BG- 11), 1:4) which generated the growth of C. ellipsoidea for 28 days with the Optical Density (OD) value of 1.43 ± 0.01 followed by BG-11 medium OD value of 1.41 ± 0.02) and the 3rd medium (NPK+ mixture of pumpkin rind water and BG-11, 1:1, OD value of 1.32 ± 0.01), respectively. The chemical contents of C. ellipsoidea cultured in 7th medium contained 54.25 ± 0.06 % protein, 15.95 ± 0.87 % carbohydrates, 9.35 ± 0.05 % fat, and 20.30 ± 0.33 % ash, meanwhile 53.37 ± 0.77 % protein, 12.83 ± 0.62 % carbohydrates, 17.80 ± 0.23 % fat, and 23.30 ± 1.33 % ash in the 3rd medium. The results obtained from this investigation indicate that pumpkin rind and seeds not only can be exploited for the antidiabetic and anti-inflammatory components but also can be applied instead of the conventional medium for the culture of C. ellipdoidea. Therefore, bio-waste from pumpkin could be potentially utilized as the source of natural antidiabetic inhibitors, anti-inflammatory drugs and the effective components of C. ellipdoidea culture media. [ABSTRACT FROM AUTHOR]

The present study investigated the phycoremediation efficacy of two freshwater green microalgae Chlorella ellipsoidea and Desmodesmus opoliensis for treatment of water of Ellenga beel, a wetland located in the vicinity of Nagaon paper mill and into which effluents of the paper mill are drained-off. After inoculation of water samples with the two freshwater green microalgae, the culture medium were analyzed for various physicochemical parameters such as pH, electrical conductivity, total dissolved solids, phosphate, nitrate, potassium, chloride, phenol, cyanide, biological oxygen demand, chemical oxygen demand and heavy metals at every seven days interval for a period of 42 days. A reduction of phosphate (85%), sulfate (96%), nitrate (76%) and chloride (48%) was observed after 42 days of incubation in the tested beel water. The micro algal incubation also resulted in decrease of heavy metal such as Pb (54%), Zn (98%), Cr (59%), and Cu (61%). Comparison of Fourier transform infrared spectra of beel water samples (control) with those inoculated with the test micro algal species showed presence of binding sites for certain functional groups like phosphate, amide, carbohydrate and alkyl halides in inoculated samples. D. opoliensis exhibited higher phycoremediation efficiency than C. ellipsoidea in removal of pollutants from the beel water samples. [ABSTRACT FROM AUTHOR]

Chlorella ellipsoidea is a freshwater green microalga that has great prospect for the sustainable development of aquaculture industry. Microalgae require optimal lighting conditions for efficient photosynthesis. The key to cost-effective algal biomass production is to optimize algae growth conditions. This study aimed to investigate the effects of various wavelengths viz. white (380–750 nm), green (510 nm), blue (475 nm), and red (650 nm) light-emitting diodes (LEDs) on the growth, pigment content (chlorophyll-a, chlorophyll-b, and β-carotene), and proximate composition of C. ellipsoidea with a photoperiod of 12 h:12 h light: dark cycle under indoor environmental conditions. C. ellipsoidea was cultured in Bold's Basal Medium for 18 days. The cell density (125.36×105 cells ml−1), cell dry weight (58.9 ± 4.57 mg L−1), optical density (1.66 ± 0.08 g L−1), chlorophyll-a (7.31 ± 0.04 μg ml−1), chlorophyll-b (2.73 ± 0.13 μg ml−1), and β-carotene (0.39 ± 0.04 μg ml−1) content of C. ellipsoidea were significantly (P < 0.05) higher at 15th-day when cultured under blue LED light exposure. Significantly lower growth and nutritional values were obtained under red LED light exposure compared to the control and other LEDs spectra. In Pearson correlation analysis, the cell density and cell dry weight values showed a strong positive correlation with the values of pigment contents of C. ellipsoidea in all the treatments. The LEDs light spectra showed significant effects on proximate composition of C. ellipsoidea. Protein and lipid contents of C. ellipsoidea were significantly higher in blue LED growth conditions compared to white, green, and red LEDs. C. ellipsoidea cells were 3˗7.04 μm in size and the maximum area of the cell was 38.94 μm2 in blue LED treatment. Results of this study demonstrated that blue LED light spectra was the most suitable condition to induce nutritionally rich biomass production of C. ellipsoidea, which can be used as a potential source of fish feed towards sustainable aquaculture.

Microalgae are considered to be a highly promising source for the production of biodiesel. However, the regulatory mechanism governing lipid biosynthesis has not been fully elucidated to date, and the improvement of lipid accumulation in microalgae is essential for the effective production of biodiesel. In this study, LEAFY COTYLEDON1 (LEC1) from Arabidopsis thaliana, a transcription factor (TF) that affects lipid content, was transferred into Chlorella ellipsoidea. Compared with wild-type (WT) strains, the total fatty acid content and total lipid content of AtLEC1 transgenic strains were significantly increased by 24.20–32.65 and 22.14–29.91%, respectively, under mixotrophic culture conditions and increased by 24.4–28.87 and 21.69–30.45%, respectively, under autotrophic conditions, while the protein content of the transgenic strains was significantly decreased by 18.23–21.44 and 12.28–18.66%, respectively, under mixotrophic and autotrophic conditions. Fortunately, the lipid and protein content variation did not affect the growth rate and biomass of transgenic strains under the two culture conditions. According to the transcriptomic data, the expression of 924 genes was significantly changed in the transgenic strain (LEC1-1). Of the 924 genes, 360 were upregulated, and 564 were downregulated. Based on qRT-PCR results, the expression profiles of key genes in the lipid synthesis pathway, such as ACCase, GPDH, PDAT1, and DGAT1, were significantly changed. By comparing the differentially expressed genes (DEGs) regulated by AtLEC1 in C. ellipsoidea and Arabidopsis, we observed that approximately 59% (95/160) of the genes related to lipid metabolism were upregulated in AtLEC1 transgenic Chlorella. Our research provides a means of increasing lipid content by introducing exogenous TF and presents a possible mechanism of AtLEC1 regulation of lipid accumulation in C. ellipsoidea.

Antimicrobial peptides are short peptides with broad-spectrum antimicrobial properties. Heliomicin, a peptide from Heliothis virescens, was re-engineered to have both antifungal and bacterial activities and renamed as HeM. Chlorella is a perfect bioreactor candidate due to fast growth, high photosynthetic efficiency, and easy large-scale culture. This study describes the successful transformation of HeM into Chlorella ellipsoidea F962. A binary expression vector pGcp4 was constructed that carried the antimicrobial peptide gene HeM and the gene encoding neomycin phosphotransferase II (NPT II). The pGcp4 was introduced into C. ellipsoidea F962 by magnetic nanoparticle-mediated transformation method. The positive transformants were obtained by G418 resistance screening. Molecular and genetic analyses on transformants revealed that the antimicrobial peptide gene and the NPT II gene had successfully entered C. ellipsoidea and expressed antimicrobial activity in transgenic cells. This method can provide a new way to produce transgenic Chlorella as well as explore wide utilization of Chlorella through magnetic transformation methods to mediate the production of antimicrobial peptides by C. ellipsoidea. [ABSTRACT FROM AUTHOR]

A facile, convenient and green method has been employed for the synthesis of silver nanoparticles (AgNPs) using dried biomass of a green alga, Chlorella ellipsoidea. The phytochemicals from the alga, as a mild and non‐toxic source, are believed to serve as both reducing and stabilizing agents. The formation of silver nanoparticles was confirmed from the appearance of a surface plasmon resonance band at 436 nm and energy dispersive X‐ray spectroscopy. The transmission electron microscopy images showed the nanoparticles to be nearly spherical in shape with different sizes. A dynamic light scattering study revealed the average particle size to be 220.8 ± 31.3 nm. Fourier transform infrared spectroscopy revealed the occurrence of alga‐derived phytochemicals attached to the outer surface of biogenically accessed silver nanoparticles. The powder X‐ray diffraction study revealed the face‐centred cubic crystalline structure of the nanoparticles. The as‐synthesized biomatrix‐loaded AgNPs exhibited a high photocatalytic activity for the degradation of the hazardous pollutant dyes methylene blue and methyl orange. The catalytic efficiency was sustained even after three reduction cycles. A kinetic study indicated the degradation rates to be pseudo‐first order with the degradation rate being 4.72 × 10−2 min−1 for methylene blue and 3.24 × 10−2 min−1 for methyl orange. The AgNPs also exhibited significant antibacterial activity against four selected pathogenic bacterial strains. [ABSTRACT FROM AUTHOR]

An experiment of algal culture was conducted in natural light and temperature conditions at a balcony of a room at the 2nd floor of Fisheries Faculty Building facing the north. The experiment was done to evaluate the growth of Chlorella ellipsoidea in four different media, viz, medium I (inorganic), medium II (organic, whole pulse powder extract), medium III (organic, whole lentil powder extract) and medium IV (organic, whole gram powder extract) under natural environment conditions during January-June, 2015. Growth rates of the algal species in four different media were found not significantly different. The alga, C. ellipsoidea attained maximum cell density of 28.89×106 cell ml-1 in the 15th day in medium I, of 30.69×106 cell ml-1 in the 13th day in medium II, of 26.18×106 cell ml-1 in the 15th day in medium III and of 21.12×106 cell ml-1 in the 13th day in medium IV. The ranges of air temperature, water temperature and light intensity were 21°C to 38°C, 23°C to 36°C and 2.28×103to 9.60×103 Lux respectively during the culture period. The average sunshine period was 5.87±2.82 hrs. Total alkalinity, free CO2, pH , NO3-N and PO4-P of algal culture media I, II, III and IV were 128, 540, 554 and 322 mgL-1; 32, 162, 102, 70 mgL-1; 7.4, 8, 7.9 and 7.9; 180, 36.6, 62.4 and 150 mgL-1, and 25.2, 48.2, 42.4 and 45.6 mgL-1, respectively. According to ANOVA of cell densities of cultures of C. ellipsoidea under treatments are not significantly different (F=1.441077). It is clear that differences between them are not significant i.e. mean algal cell densities are more or less same as differences between treatments are less than 20%.

The successful production of microalgal biomass requires the precise coordination of many different steps. Cell harvesting is a central process in all methods currently used for the production of microalgal biomass. Therefore, improving the harvesting process itself, and using a harvesting method that is compatible with adjacent steps, is necessary to prevent problems that may occur during downstream processing. This study examined the potential of the cationic biopolymer ε-poly-l-lysine (ε-PLL) for use in the harvest of microalgae (Chlorella ellipsoidea). The effects of ε-PLL concentration and mixing intensity on flocculation efficiency and operating costs were determined. We found that ε-PLL was not toxic to microalgal cells at concentrations of up to 25 mg/L, based on the photosystem II quantum yield. A recovery rate of 95% was achieved using 19 mg/L ε-PLL, and the estimated harvest cost was 20 US$/ton of harvested biomass. Moreover, ε-PLL displayed antimicrobial properties, leaving the harvested biomass intact and pure. Therefore, the use of ε-PLL-induced flocculation appears to be an attractive option when harvesting microalgal biomass for use as low- and high-value commodities for humans or animals. [ABSTRACT FROM AUTHOR]

α-Glucosidase inhibitors are used therapeutically to treat type-2 diabetes mellitus. Through a bioassay-guided fractionation technique, three carotenoids, (all-E)-lutein, (all-E)-zeaxanthin and (9-Z)-zeaxanthin, were purified from the green alga Chlorella ellipsoidea, in which (all-E)-lutein and (9-Z)-zeaxanthin had potent α-glucosidase inhibitory activity. IC50 values of (all-E)-lutein and (9-Z)-zeaxanthin were 70 and 53.5 μmol L−1 against Saccharomyces cerevisiae α-glucosidase, respectively, with non-competitive inhibition. In addition, IC50 values of (9-Z)-zeaxanthin against Bacillus stearothermophilus and rat-intestinal α-glucosidase were 805.1 and 671.2 μmol L−1, respectively. The Ki values of (all-E)-lutein and (9-Z)-zeaxanthin against S. cerevisiae α-glucosidase were 78.1 and 16.5 μmol L−1, respectively. Therefore, C. ellipsoidea carotenoids might be utilized as a novel candidate to prevent type-2 diabetes mellitus related disorders in food and medical industry. [ABSTRACT FROM AUTHOR]

Microalgae have been extensively studied for the production of various products. However, to date, microalgal biomass has not become economically feasible, mainly due to different issues such as contamination from various sources that occurs during downstream processes, and which leads to low quality biomass with limited application. In this study, to overcome contamination by flocculants and other microorganisms, the cationic biopolymer α-Poly- l -lysine (α-PLL) was applied. The cationic amine moiety and polymeric chain of α-PLL rendered microalgal harvesting efficient. With increasing α-PLL chain length, efficient dose- and time-dependent harvesting was achieved. In addition to efficient flocculation performance, biomass harvested using α-PLL showed suppressed biological contamination through the inherent antimicrobial activity of α-PLL. Thus, it is possible to upgrade the quality and storability of produced microalgal biomass using α-PLL-induced flocculation. [ABSTRACT FROM AUTHOR]

We investigated the effects of the protein and sulfate content, as well as the molecular weight ( M w ), of green alga Chlorella ellipsoidea polysaccharides on their immunomodulatory activity. The deproteinized (DP 1-3 ), desulfated (DS 1-3 ), and hydrolyzed (DH 1-3 ) derivatives of C. ellipsoidea polysaccharides were prepared by enzymatic hydrolysis, desulfation, and acid hydrolysis, respectively, of differing durations, resulting in preparations containing various amounts of proteins (2.41%–8.97%), sulfates (1.36%–4.89%), and M w (51.5–193.4 kDa). The DH 1-3 -induced production of nitric oxide (NO) by RAW264.7 cells, decreased as the M w of DH 1-3 decreased. In addition, the sulfate content and M w of DS 1-3 affected the release of NO. However, lower protein content did not affect DP 1-3 -induced NO release and cytokine mRNA expression in RAW264.7 cells. Based on a multiple regression analysis of the effects of protein content, sulfate content, and M w , on NO release, we found that M w was a key factor for the stimulation of RAW264.7 cells, as it affected cytokine production, and activation of the nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. Therefore, the M w of C. ellipsoidea polysaccharides played an important role in their immunomodulatory activities. [ABSTRACT FROM AUTHOR]

Background: Oil in the form of triacylglycerols (TAGs) is quantitatively the most important storage form of energy for eukaryotic cells. Diacylglycerol acyltransferase (DGAT) is considered the rate-limiting enzyme for TAG accumulation. Chlorella, a unicellular eukaryotic green alga, has attracted much attention as a potential feedstock for renewable energy production. However, the function of DGAT1 in Chlorella has not been reported. Results: A full-length cDNA encoding a putative diacylglycerol acyltransferase 1 (DGAT1, EC 2.3.1.20) was obtained from Chlorella ellipsoidea. The 2,142 bp open reading frame of this cDNA, designated CeDGAT1, encodes a protein of 713 amino acids showing no more than 40% identity with DGAT1s of higher plants. Transcript analysis showed that the expression level of CeDGAT1 markedly increased under nitrogen starvation, which led to significant triacylglycerol (TAG) accumulation. CeDGAT1 activity was confirmed in the yeast quadruple mutant strain H1246 by restoring its ability to produce TAG. Upon expression of CeDGAT1, the total fatty acid content in wild-type yeast (INVSc1) increased by 142%, significantly higher than that transformed with DGAT1s from higher plants, including even the oil crop soybean. The over-expression of CeDGAT1 under the NOS promoter in wild-type Arabidopsis thaliana and Brassica napus var. Westar significantly increased the oil content by 8-37% and 12-18% and the average 1,000-seed weight by 9-15% and 6-29%, respectively, but did not alter the fatty acid composition of the seed oil. The net increase in the 1,000-seed total lipid content was up to 25-50% in both transgenic Arabidopsis and B. napus. Conclusions: We identified a gene encoding DGAT1 in C. ellipsoidea and confirmed that it plays an important role in TAG accumulation. This is the first functional analysis of DGAT1 in Chlorella. This information is important for understanding lipid synthesis and accumulation in Chlorella and for genetic engineering to enhance oil production in microalgae and oil plants. [ABSTRACT FROM AUTHOR]

Polysaccharides of green alga Chlorella ellipsoidea were extracted using hot water and fractionated using an anion-exchange chromatography to investigate their molecular characteristics and immunomodulatory activities. The crude polysaccharide and two fractions (F 1 and F 2 ) consisted mainly of carbohydrate (68.1–89.7%) and protein (2.0–11.8%) with small amounts of sulfate (1.9–6.1%) and uronic acid (0.5–6.1%). Glucose (58.8–97.6%) was the major monosaccharide of these polysaccharides, with different levels of rhamnose (0.2–11.6%), mannose (0.4–2.6%), and galactose (1.8–27.0%). The average molecular weights ( M w ) of the crude, F 1 , and F 2 were 175.8 × 10 3 , 126.9 × 10 3 , and 237.0 × 10 3 g/mol, respectively. The crude, F 1 , and F 2 stimulated murine macrophage, RAW264.7 cells, to produce considerable amounts of nitric oxide (NO) and various cytokines via up-regulation of their mRNA expression by the activation of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. The fraction F 2 with higher M w and protein content showed stronger immunomodulatory activity. The main backbone of the fraction F 2 was mainly connected via (1 → 4)-linked glucose and (1 → 6)-linked galactose with branches at C-3 and C-4 positions in (1 → 3,4)-linked glucose and (1 → 4,6)-linked galactose residues, respectively. [ABSTRACT FROM AUTHOR]

Growth of Chlorella ellipsoidea was analyzed using various autotrophic media viz. Bold's basal medium (BBM), wright's cryptophyte medium (WC), closterium medium (C), and blue green medium (BG11) medium. BG11 was showed to be the most excellent medium for growth and biomass production (3.2 g L − 1 ). WC was the best medium for lipid production. Maximum lipid production 1184 mg L − 1 (a mass fraction of 37% on dry weight basis) was achieved when the cells in the late-exponential growth phase in BG11 medium were collected by centrifugation and reinoculated into WC media. The findings of gravimetric method were comparable with nile red fluorescence method of lipid determination. Total fatty acid (TFA) composition varies with culture media composition. Highest TFA yield of 2.2 g L − 1 and a TFA content of a mass fraction of 24.1% (DW) with a mass fraction of 95% TFA C18 (a mass fraction of ~ 71.5%) and C16 (a mass fraction of ~ 23.5%) was obtained with BG11 medium after reinoculation into WC media. C . ellipsoidea was discovered as rich source of protein and carbohydrate also. [ABSTRACT FROM AUTHOR]

Residues of iprodione, used for the control of fungal diseases in crops, endanger both human health and ecosystem functioning. In this study, we isolated an iprodione-degrading bacteria, Pseudarthrobacter sp. Y-5, able to grow on iprodione as the sole carbon source. To achieve the high-level stable synthesis of iprodione hydrolase (IpaH), an unmarked genetic engineering approach was used to construct Bacillus subtilis WB800- ipaH , which showed the extracellular secretion and expression of the ipaH gene. Strain WB800- ipaH had superior degradability and showed cost-effectiveness potential for the bioremediation of iprodione-polluted environments than those of strain Y-5. Furthermore, iprodione suppressed Chlorella ellipsoidea growth and was toxic to Daphnia magna , while strains Y-5 and WB800- ipaH were both capable of degrading iprodione to relieve its toxicity. Both Y-5 (107 CFU g−1 soil) and WB800- ipaH (105 CFU g−1 soil) could eliminate >90% of 5 and 20 mg kg−1 iprodione in field soil within 9 d and 15 d, respectively. This work provides strain resources for eliminating the residue of iprodione in the environment. [Display omitted] • An iprodione-degrading strain Pseudarthrobacter sp. Y-5 was isolated. • An unmarked engineered strain Bacillus subtilis WB800- ipaH was constructed. • The extracellular expression of ipaH was first reported. • Degradation of iprodione relieved its toxicity against C. ellipsoidea and D. magna. • Strain WB800- ipaH showed cost-effective potential in iprodione degradation than Y-5. [ABSTRACT FROM AUTHOR]

[Display omitted] • Composition controllable CuS nanoparticles have been synthesized using a facile and sustainable strategy. • An edible freshwater green alga, Chlorella ellipsoidea has been used. • The CuS NPs showed enhanced photocatalytic activity for degradation of methylene blue. A facile, convenient and green method has been devised for the synthesis of a covellite phase copper sulfide nanoparticles (CuSNPs) using aqueous extract of a green alga, Chlorella ellipsoidea. The algal phytochemicals are conjectured to have served as both reducing and capping agent. The absorption features in the NIR region of the UV–visible-NIR spectrum confirmed the formation of covellite copper sulfide nanostructures. The FTIR spectrum of the as-synthesized CuSNPs indicated the involvement of functional groups of biomolecule as surface-ligands on the outer surface of the nanoparticle. The XRD reflections were indexed to hexagonal phase covellite CuS structure. The TEM study revealed a predominantly spherical morphology of particle size in the range of 9–23 nm with some agglomeration. The dark field microscope images also confirm the formation of CuS nanoparticles. EDX analysis of the synthesized nanoparticles confirms the presence of only 'Cu' and 'S' indicating formation of pure CuS nanoparticles. The as-synthesized nanoparticles exhibited excellent photocatalytic property for the degradation of a water soluble toxic methylene blue dye under scattered sunlight. The dye degradation (rate = 0.03692 min−1) was ascertained to be pseudo-first order with regression coefficient, R2 being 0.96884. The photocatalyst is readily recoverable and showed excellent stability even after four cycles. [ABSTRACT FROM AUTHOR]

Background The lipid content of microalgae is regarded as an important indicator for biodiesel. Many attempts have been made to increase the lipid content of microalgae through biochemical and genetic engineering. Significant lipid accumulation in microalgae has been achieved using biochemical engineering, such as nitrogen starvation, but the cell growth was severely limited. However, enrichment of lipid content in microalgae by genetic engineering is anticipated. In this study, GmDof4 from soybean (Glycine max), a transcription factor affecting the lipid content in Arabidopsis, was transferred into Chlorella ellipsoidea. We then investigated the molecular mechanism underlying the enhancement of the lipid content of transformed C. ellipsoidea. Results We constructed a plant expression vector, pGmDof4, and transformed GmDof4 into C. ellipsoidea by electroporation. The resulting expression of GmDof4 significantly enhanced the lipid content by 46.4 to 52.9%, but did not affect the growth rate of the host cells under mixotrophic culture conditions. Transcriptome profiles indicated that 1,076 transcripts were differentially regulated: of these, 754 genes were significantly upregulated and 322 genes were significantly downregulated in the transgenic strains under mixotrophic culture conditions. There are 22 significantly regulated genes (∣log2 ratio∣ >1) involved in lipid and fatty acid metabolism. Quantitative real-time PCR and an enzyme activity assay revealed that GmDof4 significantly up-regulated the gene expression and enzyme activity of acetylcoenzyme A carboxylase, a key enzyme for fatty acid synthesis, in transgenic C. ellipsoidea cells. Conclusions The hetero-expression of a transcription factor GmDof4 gene from soybean can significantly increase the lipid content but not affect the growth rate of C. ellipsoidea under mixotrophic culture conditions. The increase in lipid content could be attributed to the large number of genes with regulated expression. In particular, the acetyl-coenzyme A carboxylase gene expression and enzyme activity were significantly upregulated in the transgenic cells. Our research provides a new way to increase the lipid content of microalgae by introducing a specific transcription factor to microalgae strains that can be used for the biofuel and food industries. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fe3O4–PEI nanocomposites with large amount of NH2 groups were synthesized. [•] 97% of harvesting efficiency for microalgal cells was obtained with the nanocomposites. [•] Magnetic separation provides a powerful tool for microalgae harvesting in practice. [ABSTRACT FROM AUTHOR]

Highlights: [•] A magnetic separator was developed for microalgae harvesting. [•] 95% of harvesting efficiency was achieved in both batch and continuous operation. [•] Microalgae harvesting performance was stable in optimized operation conditions. [ABSTRACT FROM AUTHOR]

Highlights: [•] Chlorella ellipsoidea cells were cultivated in bubble column bioreactors. [•] Microalgal cells were able to quickly adapt to the outdoor conditions. [•] Biomass production cost in outdoor culture was lower than that in indoor culture. [ABSTRACT FROM AUTHOR]

Dimethachlon, a broad-spectrum dicarboximide fungicide, poses a hazard to the safety of human and ecosystem due to its residue in the environment. A high-efficient dimethachlon degrading bacteria JH-1 belonging to Paenarthrobacter sp. was isolated and characterized. Strain JH-1 can utilize high concentration of dimethachlon as sole carbon source for growth and degrade 98.53% of 300 mg·L−1 dimethachlon within 72 h. Crude enzyme of strain JH-1 could degrade 99.76% of 100 mg·L−1 dimethachlon within 2 h. The optimum degradation condition of dimethachlon by strain JH-1 was at 35 °C and pH 7.0. Dimethachlon was degraded in Paenarthrobacter sp. JH-1 as following: it was firstly converted to 4-(3,5-dichloroanilino)-4-oxobutanoic acid and then subjected to the hydrolysis to 3,5-dichloroaniline and succinic acid, the latter was further degraded. Dimethachlon inhibited the growth of Chlorella ellipsoidea , while Paenarthrobacter sp. JH-1 could degrade dimethachlon to relieve its toxicity. This work facilitates our knowledge of the degradation mechanism of dimethachlon and offers potential resource of microbial strains for the bioremediation of dimethachlon-contaminated environments in the future. • A Gram-positive dimethachlon-degrading strain Paenarthrobacter sp. JH-1 was first reported. • Strain JH-1 could utilize high concentration of dimethachlon for growth. • Strain JH-1 could eliminate dimethachlon and relieve its toxicity against Chlorella ellipsoidea. • Strain JH-1 provides a potential candidate for bioremediation of dimethachlon-contaminated environments. [ABSTRACT FROM AUTHOR]

Chlorella ellipsoidea is a single-celled eukaryotic green microalgae with high nutritional value. Its value may be further increased if a simple, reliable and cost-effective transformation method for C. ellipsoidea can be developed. In this paper, we describe a novel transformation method for C. ellipsoidea . This system is based on treatment of C. ellipsoidea cells with cellulolytic enzymes to weaken their cell walls, making them become competent to take up foreign DNA. To demonstrate the usefulness and effectiveness of this method, we treated C. ellipsoidea cells with a cell wall-degrading enzyme, cellulase, followed by transformation with plasmid pSP-Ubi-GUS harbouring both the zeocin resistance gene and the beta-glucuronidase (GUS) reporter gene that serve as selective makers for transformation. Transformants were readily obtained on zeocin selection medium, reaching transformation efficiency of 2.25 × 10 transformants/μg of plasmid DNA. PCR analysis has also demonstrated the presence of the GUS reporter gene in the zeocin-resistant transformants. Histochemical assays further showed the expression of the GUS activity in both primary transformants and transformants after long-term growth (10 months) with antibiotic selection on and off. Availability of a simple and efficient transformation system for C. ellipsoidea will accelerate the exploration of this microalga for a broader range of biotechnological applications, including its use as a biologic factory for the production of high-value human therapeutic proteins. [ABSTRACT FROM AUTHOR]

The total zeaxanthin level in Chlorella ellipsoidea, a green microalga, was more than nine times that of red pepper, a plant source of zeaxanthin. Additionally, the zeaxanthin in C. ellipsoidea consisted of the free form, while those in other plants exist as zeaxanthin mono- and diesters. Pressurized liquid extraction (PLE) was used to extract zeaxanthin from C. ellipsoidea. Both the extraction temperature and extraction time, the two main factors in PLE, were optimized with a central composite design to obtain the highest extraction efficiency of zeaxanthin. Hexane, ethanol, and isopropanol were used as PLE extraction solvents. Ethanol extracted zeaxanthin most efficiently from C. ellipsoidea. Temperature was the parameter with the strongest influence on the extraction of zeaxanthin. The optimum extraction temperature and time for zeaxanthin were 115.4°C and 23.3 min, respectively. The maximum predicted value of 4.28 mg g agreed with the experimental value of 4.26 mg g, supporting the quality of the fitted model. These results indicate that PLE using ethanol may be a useful method for extracting zeaxanthin from C. ellipsoidea. [ABSTRACT FROM AUTHOR]

Abstract: Protein derived the marine Chlorella ellipsoidea was hydrolyzed using different proteases (papain, trypsin, pepsin and α-chymotrypsin) for production of antioxidative peptide, and the antioxidant activities of their hydrolysates were investigated using free radical scavenging assay by electron spin resonance spin-trapping technique. Among the hydrolysates, the peptic hydrolysate exhibited the highest antioxidant activity compared to other hydrolysates. To identify antioxidant peptide, the peptic hydrolysate was purified using consecutive chromatographic methods, and the antioxidant peptide was identified to be Leu-Asn-Gly-Asp-Val-Trp (702.2Da) by Q-TOF ESI mass spectroscopy. The antioxidant peptide scavenged peroxyl, DPPH and hydroxyl radicals at the IC50 values of 0.02, 0.92 and 1.42mM, respectively. The purified peptide enhanced cell viability against AAPH-induced cytotoxicity on normal cells. Furthermore, the purified peptide reduced the proportion of apoptotic and necrotic cells induced by AAPH, as demonstrated by decreased sub-G1 hypodiploid cells and decreased apoptotic body formation by flow cytometry. [Copyright &y& Elsevier]

Abstract: A simple and rapid harvesting method by in situ magnetic separation with naked Fe3O4 nanoparticles has been developed for the microalgal recovery of Botryococcus braunii and Chlorella ellipsoidea. After adding the magnetic particles to the microalgal culture broth, the microalgal cells were adsorbed and then separated by an external magnetic field. The maximal recovery efficiency reached more than 98% for both microalgae at a stirring speed of 120r/min within 1min, and the maximal adsorption capacity of these Fe3O4 nanoparticles reached 55.9mg-dry biomass/mg-particles for B. braunii and 5.83mg-dry biomass/mg-particles for C. ellipsoidea. Appropriate pH value and high nanoparticle dose were favorable to the microalgae recovery, and the adsorption mechanism between the naked Fe3O4 nanoparticles and the microalgal cells was mainly due to the electrostatic attraction. The developed in situ magnetic separation technology provides a great potential for saving time and energy associated with improving microalgal harvesting. [Copyright &y& Elsevier]

Abstract: The contamination of groundwater by methyl tert-butyl ether (MTBE) is one of the most serious environmental problems around the world. MTBE degradation in a closed algal–bacterial symbiotic system, containing a mixed culture of Methylibium petroleiphilum PM1 and Chlorella ellipsoidea, was investigated. The algal–bacterial symbiotic system showed increased MTBE degradation. The MTBE-degradation rate in the mixed culture (8.808±0.007mgl−1 d−1) was higher than that in the pure bacterial culture (5.664±0.017mgl−1 d−1). The level of dissolved oxygen was also higher in the mixed culture than that in the pure bacterial culture. However, the improved efficiency of MTBE degradation was not in proportional to the biomass of the alga. The optimal ratio of initial cell population of bacteria to algae was 100:1. An immobilized culture of mixed bacteria and algae also showed higher MTBE degradation rate than the immobilized pure bacterial culture. A mixed culture with algae and PM1 immobilized separately in different gel beads showed higher degradation rate (8.496±0.636mgl−1 d−1) than that obtained with algae and PM1 immobilized in the same gel beads (5.424±0.010mgl−1 d−1). [ABSTRACT FROM AUTHOR]

The goal of the present investigation was to study the effect of pH on growth and biochemical responses of Dunaliella bardawil and Chlorella ellipsoidea when exposed to different pH values. The two tested microalgae could grow in a wide range of pH (4–9 for D. bardawil and 4–10 for C. ellipsoidea). The dry weight gain and the biochemical components of D. bardawil were greatly enhanced at pH 7.5. In contrast, dry weight and carbohydrate content of C. ellipsoidea attained their maximum values at the alkaline pH. On the other hand, the protein content of C. ellipsoidea recorded its highest value at pH 4, while the pigment content of the same alga was highest at pH 4, 6, and 7.5 and decreased at alkaline pH. Both pH 6 and pH 9 stimulated the accumulation of β-carotene, vitamin E and vitamin C in D. bardawil, with the highest values of the three compounds recorded at pH 9. In the case of C. ellipsoidea, β-carotene content increased at pH 6 and pH 10 as compared with the control, but the amount of β-carotene was much higher at pH 6 than at pH 10. Vitamin E content was higher in C. ellipsoidea cells at pH 10 than at pH 6. Both pH 6 and pH 10 caused a significant decline in vitamin C content of C. ellipsoidea. [ABSTRACT FROM AUTHOR]

Eight bacterial strains identified as P1, P2, Y1, Y2, W1, W2, G, and R were isolated from a long-term laboratory culture of the green alga Chlorella ellipsoidea. Although it is unknown how these bacterial strains have been maintained with the C. ellipsoidea culture, all appeared to promote the growth of C. ellipsoidea. Co-inoculation of each bacterial strain with C. ellipsoidea resulted in 0.5–3 times greater algal growth than that of C. ellipsoidea alone. The most effective bacterium (i.e., strain P1) was selected and further characterized. Biochemical analysis and transmission electron microscopy revealed that strain P1 is closely related to the genus Brevundimonas. Sequence analysis of the 16S rRNA of strain P1 showed 99.9 and 99.4% nucleotide sequence identity to that of B. nasdae and B. vesicularis, respectively. In addition to the growth promotion of C. ellipsoidea by strain P1, the growth of strain P1 was also significantly enhanced by co-culturing with C. ellipsoidea, indicating a symbiotic relationship between the bacterium and alga. Scanning electron microscopy showed the direct adhesion of strain P1 cells to the surface of C. ellipsoidea cells, as well as the development of abundant crinkles on the surface of co-cultured C. ellipsoidea cells. [ABSTRACT FROM AUTHOR]

The effects of temperature and salinity on growth of green algae Chlorella ellipsoidea and Nannochloris oculata were determined to compare the optimum culture conditions. A four-temperature (15, 20, 25, and 30°C) × three-salinity (10, 20, and 30) factorial design with triplicates was applied. Specific growth rate (SGR), maximum density, and duration to reach maximum density of C. ellipsoidea were significantly affected by both temperature and salinity. The highest SGR was observed in C. ellipsoidea at 25°C and salinity 10, but the maximum density was very low. The highest maximum density was achieved in C. ellipsoidea at 15°C and 10. The slope constant of the linear relationship between semilogarithmic growth of C. ellipsoidea and day of culture was highest at 15°C and 10. The SGR and duration to reach maximum density of N. oculata were significantly affected by both temperature and salinity. However, maximum density of N. oculata was significantly affected by temperature, but not salinity. The highest maximum density was achieved in N. oculata at 25°C and 30, but SGR was significantly lower than that of N. oculata at 25°C and 10. The slope constant of the linear relationship between semilogarithmic growth of N. oculata and day of culture was highest at 25°C and 30. Based on these results, the condition of 15°C and salinity 10 seemed to be optimal for maximum density of C. ellipsoidea, and the condition of 25°C and 10 and 30 for SGR and maximum density for N. oculata, respectively. [ABSTRACT FROM AUTHOR]

A highly efficient system was developed for the expression of foreign genes in Chlorella ellipsoidea cells. The effect of five promoters on the expression efficiency of β-glucuronidase (GUS) gene was evaluated by transient expression of the UidA gene. Among these promoters, Ubiquitin-Ω was found to be the most efficient and was selected to drive the expression of foreign genes in Chlorella cells. A gene encoding the mature rabbit neutrophil peptide-1 (NP-1) was introduced into the cells. Integration of the gene for NP-1 into the Chlorella genome was confirmed by PCR and Southern blot analysis. In vitro anti-microbial testes demonstrated the expression of biologically active NP-1 by the transgenic Chlorella cells. [ABSTRACT FROM AUTHOR]

Chlorella ellipsoidea is a freshwater green microalga that has great prospect for the sustainable development of aquaculture industry. Microalgae require optimal lighting conditions for efficient photosynthesis. The key to cost-effective algal biomass production is to optimize algae growth conditions. This study aimed to investigate the effects of various wavelengths viz. white (380-750 nm), green (510 nm), blue (475 nm), and red (650 nm) light-emitting diodes (LEDs) on the growth, pigment content (chlorophyll-a, chlorophyll-b, and β-carotene), and proximate composition of C. ellipsoidea with a photoperiod of 12 h:12 h light: dark cycle under indoor environmental conditions . C. ellipsoidea was cultured in Bold's Basal Medium for 18 days. The cell density (125.36×10 5 cells ml -1 ), cell dry weight (58.9 ± 4.57 mg L -1 ), optical density (1.66 ± 0.08 g L -1 ), chlorophyll-a (7.31 ± 0.04 μg ml -1 ), chlorophyll-b (2.73 ± 0.13 μg ml -1 ), and β-carotene (0.39 ± 0.04 μg ml -1 ) content of C. ellipsoidea were significantly (P < 0.05) higher at 15 th -day when cultured under blue LED light exposure. Significantly lower growth and nutritional values were obtained under red LED light exposure compared to the control and other LEDs spectra. In Pearson correlation analysis, the cell density and cell dry weight values showed a strong positive correlation with the values of pigment contents of C. ellipsoidea in all the treatments. The LEDs light spectra showed significant effects on proximate composition of C. ellipsoidea . Protein and lipid contents of C. ellipsoidea were significantly higher in blue LED growth conditions compared to white, green, and red LEDs. C. ellipsoidea cells were 3-7.04 μm in size and the maximum area of the cell was 38.94 μm 2 in blue LED treatment. Results of this study demonstrated that blue LED light spectra was the most suitable condition to induce nutritionally rich biomass production of C. ellipsoidea , which can be used as a potential source of fish feed towards sustainable aquaculture., Competing Interests: The authors declare no conflict of interest., (© 2021 The Author(s).)

This article focuses on the pH-dependent regulation of carbonic anhydrase induction and change in photosynthesis during adaptation of Chlorella cells to low carbon dioxide. Algal cells grown in ordinary air exhibit higher affinity for carbon dioxide in photosynthesis and higher activity of carbonic anhydrase (CA) than those grown in carbon dioxide-enriched air. Those changes induced during adaptation to low carbon dioxide have been reported to be regulated by several environmental factors. For example, light plays an important role in CA induction and its effect is different depending on algal species.

The composition and positional distribution of fatty acids in the polar lipids from 4 strains of Chlorella differing in chilling susceptibility and frost hardiness were analyzed by enzymatic hydrolysis and gas‐liquid chromatography. Analysis of the polar lipids from chilling‐sensitive, chilling‐resistant and chilling‐sensitive revertant strains of Chlorella ellipsoidea IAM C‐102 showed that the sum of palmitic and trans‐3‐hexadecenoic acid in phosphatidylglycerol (PG) is about 60% for the sensitive strains and 53% for the resistant strain. The sum of dipalmitoyl and 1‐palmitoyl‐2‐(trans‐3‐hexadecenoyl) PG as estimated from the positional distribution of their fatty acids, is about 10% in the case of each of the three strains. The contents of unsaturated fatty acids in phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were higher in the resistant than in the sensitive strain. This suggests that unsaturation of fatty acids in not only PG but also PC and PE is involved in chilling sensitivity of Chlorella. On the other hand, lipid changes during the development of frost hardiness of C. ellipsoidea IAM C‐27, a frost hardy strain, were examined. The results showed that fatty acids in most lipid classes are unsaturated in the hardening process but their degree of unsaturation is not greatly different from that of the chilling‐resistant strain, suggesting that not only unsaturation of fatty acids in lipids but also other factors are necessary for the development of frost hardiness. [ABSTRACT FROM AUTHOR]

The uptake and accumulation of inorganic carbon has been investigated in Chlorella ellipsoidea cells grown at acid or alkaline pH. Carbonic anhydrase (CA) was detected in cell extracts but not in intact cells and CA activity in acid-grown cells was considerably less than that in alkali-grown cells. Both cell types demonstrates low K&frac1,2 (CO2) values in range pH 7.0-8.0 and these were unaffected by O2 concentration. The CO2 compensation concentration of acid- and alkali-grown cells suspended in aqueous media were not significantly different in the range of pH 6.0-8.0, but at pH 5.0, the CO2 compensation concentrations of acid-grown cells (79.2 cm³ m-3). The rate of photosynthetic O2 evolution in the range pH 7.5-8.0 exceeded the calculated rate of CO2 supply two- to three-fold, in both acid- and alkali-grown cells, indicating that HCO3- was taken up by the cells. Accumulation of inorganic carbon was measured at pH 7.5 y silicone-oil centrifugation, and the concentration of unfixed inorganic carbon was found to be 5.1 mol m-3 in acid-grown and 6.4 mol m-3 in alkali-grown cells. These concentrations were 4.6- and 5.9-fold greater than in the external medium. These results indicate that photorespiration is suppressed in both acid- and alkali-grown cells by an intracellular accumulation of inorganic carbon due, in part, to an active uptake of bicarbonate. [ABSTRACT FROM AUTHOR]

Significant progress has been made toward the successful genetic engineering of microalgal species with high potential for fuel production. Foreign DNA has been transferred into a green alga, Chlorella ellipsoidea, and has been successfully expressed in this heterologous system. In addition, electroporation has shown promise as a means of introducing DNA into intact algal cells. We have analyzed the composition of DNA from several algal species and demonstrated the presence of elevated GC contents in several green algal species. These results suggest that homologous selectable markers may be required for the development of stable transformation systems for the algae; the development of nitrate reductase and orotidine-5′-phosphate decarboxylase as homologous selectable markers for Monoraphidium minutum and for Cyclotella cryptica is in progress. We have constructed a cDNA expression library for Cyclotella cryptica, and are constructing cDNA and genomic libraries for several other algal species. The libraries will be screened with heterologous or homologous probes for nitrate reductase and acetyl-CoA carboxylase in order to clone these genes, which appear to influence lipid accumulation in the algae. This work represents important steps toward the genetic improvement of micro-algae for fuel production. [ABSTRACT FROM AUTHOR]

We report here on the development of a transient expression system for Chlorella ellipsoidea using a heterologous gene, firefly luciferase. Cells of this unicellular green alga were converted to protoplasts and treated with plasmid pDO432, which bears luciferase under the control of the CaMV 35S promoter. This treatment resulted in detectable luciferase activity in cell extracts. Expression required Cellulysin treatment, active cell metabolism, and the addition of carrier DNA and polyethylene glycol. Linearization of the luciferase plasmid did not significantly alter the activity. A time course of expression showed that luciferase is made rapidly, within about 7 h after addition of DNA, but that the activity disappears over the course of a few days. These experiments represent an important first step in the development of a Chlorella transformation system. [ABSTRACT FROM AUTHOR]

A 243 by intron was found within the 23S rRNA gene of the unicellular green alga Chlorella ellipsoidea. This intron is A+T-rich (63.7%) compared with the 23S rRNA (50.5%) and is located in domain II of the 23S rRNA. In contrast to rRNA introns so far known, this intron is considerably small and does not posses features of group I introns in spite of its possible folded secondary structure; this is a new type rRNA intron. The complete nucleotide sequence of the 23S rRNA gene (2,965 bp) was also compared with that of tobacco chloroplasts and E. coli. [ABSTRACT FROM AUTHOR]

Chlorella ellipsoidea was incubated in nitrogendeficient medium to examine the changes in the relative DNA content per nucleus, which were measured by epifluorescent microspectrophotometry combined with Feulgen-pararosaniline staining. The results were compared with synchronous multiplication in the basal medium. The minimum and maximum measured DNA values per nucleus were 2.5 and 280, which were related to 1 C and 112 C respectively. The mode of the DNA value moved reciprocally between 8 C and 4 C levels under multiplication in basal medium, which one mother cell producing four autospores in each synchronous division. The average value of the modes over 5 days of nitrogen starvation was 8 C. The frequency distribution of the relative DNA value consisted of at most five levels, 1-3.2 C, 4-12 C, 28 C, 32 C, and 40-112 C. The modal changes suggested the occurrence of DNA synthesis caused by some intracellular nitrogen pools. During the nitrogen starvation, 10-fold cell multiplication and a small amount of cell growth occurred. [ABSTRACT FROM AUTHOR]