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This study investigates the biomass and carbon fixation rate of Chlorella sp. by the main valuable elements in converter steel slag in F/2 seawater medium. The results indicate that Ca, Mg, P, Si, Fe, and Mn can increase the biomass and carbon fixation rate of Chlorella sp. , while Cu, Zn, Cr, and Al can decrease the biomass and carbon fixation rate of Chlorella sp.. Three machine learning methods known as Back Propagation neural network (BPNN), decision tree (DT), and random forest (RF) were applied to construct the prediction model for the carbon fixation rate of Chlorella sp. based on real-life experimental data obtained from single factor experiments. The overall results exhibited that the BPNN model is better than the DT model and RF model to predict the carbon fixation rate of Chlorella sp.. Finally, the maximum carbon fixation rate for Chlorella sp. predicted by BPNN model is 50.86 mg/(L·d), which was 2.46 times that of the control group, under the optimum conditions of Ca 5.77 g/L, Mg 4.74 g/L, P 1.27 g/L, Si 6.31×10−1 g/L, Fe 6.50×10−4 g/L, Mn 5.00×10−5 g/L, Cu 2.51×10−6 g/L, Zn 4.98×10−6 g/L, Cr 0 g/L, and Al 0 g/L in F/2 seawater medium. [ABSTRACT FROM AUTHOR]

Microalga of the genus Chlorella has developed a stable industry as dietary supplements for humans and animals based on their scientific and commercial interests. The growth of Chlorella sp. cultures has been enhanced by using a variety of nutrients to improve pigmentation, lipid content, and growth. Acadian Marine Plant Extract Powder (AMPEP) improves crops and macroalgae production, such as seaweeds. However, AMPEP has not yet been studied as a means of producing microalgae. Therefore, this study investigates microalgae production in a nutrient medium containing AMPEP. Three concentrations of AMPEP were prepared: group A (125 mg L-1 AMPEP), group B (625 mg L-1 AMPEP), and group C (0 mg L-1 AMPEP) as control. Experiments were conducted for each group for 21 days in triplicate. Results revealed that lower AMPEP (125 mg L-1) concentration added to the nutrient medium provides higher cell densities in Chlorella sp. culture. 125 mg L-1 AMPEP in a nutrient medium reached the highest cell density of 1.28 fold cell mL-1 than the control group. Additionally, the dry weight of groups A, B, and C were calculated as 2.57 ± 0.12 g L-1, 1.37 ± 0.06 g L-1, and 1.58 ± 0.16 g L-1, respectively. The cell sizes of groups A, B, and C were 4.80 ± 1.32 μm, 5.20 ± 1.87 μm, and 3.80 ± 0.79 μm, respectively. Moreover, the highest level of lipid accumulation of Chlorella sp. culture was achieved by group B with a lipid content of 10.44 ± 1.28 %, followed by group A with a lipid content of 8.55 ± 0.80 %, which was higher than the control group (group C) with a lipid content of 7.04 ± 0.93 %. Hence, the present study shows that AMPEP used in microalgae production may improve growth and lipid accumulation. [ABSTRACT FROM AUTHOR]

To promote the conservation of aquatic ecosystems, it is essential to delve into restoration techniques for selecting the most sustainable option for combating eutrophication. Hence, we study the effects of novel phosphorus (P) adsorbents (magnetic carbonyl iron particles, HQ, and two non-magnetic P adsorbents: CFH-12® and Phoslock®) on the growth and photosynthetic activity of Chlorella sp. More specifically, the intrinsic photochemical efficiency of PSII (ΦPSII) and the nonphotochemical quenching (NPQ) were measured in Chlorella sp. after different contact times with different concentrations of these adsorbents. Our initial hypothesis was that non-magnetic P adsorbents have more effects on the organisms than magnetic ones. However, our results did not show strong evidence of inhibitory effects caused by HQ nor CFH-12® (no significant effect size on ΦPSII), while Phoslock® showed inhibitory effects on the photosynthetic activity of Chlorella sp. for any of its concentrations (NPQ = 0). Lastly, we compared the effect of the studied P adsorbents in a real application scenery (Honda wetland, Spain). For this study case, it is likely that CFH-12® and HQ doses would not cause any negative effects on photosynthetic efficiency while Phoslock®, by limiting light availability, will drastically reduce it. [ABSTRACT FROM AUTHOR]

This study investigates the biomass and carbon fixation rate of Chlorella sp. by the main valuable elements in converter steel slag in F/2 seawater medium. The results indicate that Ca, Mg, P, Si, Fe, and Mn can increase the biomass and carbon fixation rate of Chlorella sp., while Cu, Zn, Cr, and Al can decrease the biomass and carbon fixation rate of Chlorella sp.. Three machine learning methods known as Back Propagation neural network (BPNN), decision tree (DT), and random forest (RF) were applied to construct the prediction model for the carbon fixation rate of Chlorella sp. based on real-life experimental data obtained from single factor experiments. The overall results exhibited that the BPNN model is better than the DT model and RF model to predict the carbon fixation rate of Chlorella sp.. Finally, the maximum carbon fixation rate for Chlorella sp. predicted by BPNN model is 50.86 mg/(L·d), which was 2.46 times that of the control group, under the optimum conditions of Ca 5.77 g/L, Mg 4.74 g/L, P 1.27 g/L, Si 6.31×10−1 g/L, Fe 6.50×10−4 g/L, Mn 5.00×10−5 g/L, Cu 2.51×10−6 g/L, Zn 4.98×10−6 g/L, Cr 0 g/L, and Al 0 g/L in F/2 seawater medium.

Microalga of the genus Chlorella has developed a stable industry as dietary supplements for humans and animals based on their scientific and commercial interests. The growth of Chlorella sp. cultures has been enhanced by using a variety of nutrients to improve pigmentation, lipid content, and growth. Acadian Marine Plant Extract Powder (AMPEP) improves crops and macroalgae production, such as seaweeds. However, AMPEP has not yet been studied as a means of producing microalgae. Therefore, this study investigates microalgae production in a nutrient medium containing AMPEP. Three concentrations of AMPEP were prepared: group A (125 mg L-1 AMPEP), group B (625 mg L-1 AMPEP), and group C (0 mg L-1 AMPEP) as control. Experiments were conducted for each group for 21 days in triplicate. Results revealed that lower AMPEP (125 mg L-1) concentration added to the nutrient medium provides higher cell densities in Chlorella sp. culture. 125 mg L-1 AMPEP in a nutrient medium reached the highest cell density of 1.28 fold cell mL-1 than the control group. Additionally, the dry weight of groups A, B, and C were calculated as 2.57 ± 0.12 g L-1, 1.37 ± 0.06 g L-1, and 1.58 ± 0.16 g L-1, respectively. The cell sizes of groups A, B, and C were 4.80 ± 1.32 μm, 5.20 ± 1.87 μm, and 3.80 ± 0.79 μm, respectively. Moreover, the highest level of lipid accumulation of Chlorella sp. culture was achieved by group B with a lipid content of 10.44 ± 1.28 %, followed by group A with a lipid content of 8.55 ± 0.80 %, which was higher than the control group (group C) with a lipid content of 7.04 ± 0.93 %. Hence, the present study shows that AMPEP used in microalgae production may improve growth and lipid accumulation.

Various species of macro and microalgae were characterized to identify their potential as antimicrobial agents, thereby mitigating contamination risks and enhancing food safety. The objective was to assess the bacteriostatic activity of Spirulina platensis, Scenedesmus obliquus, and Chlorella sp., as well as their suitability as constituents of an edible coating for fruits and vegetables. Coating surfaces supplemented with Chlorella sp. exhibited a macrostructured appearance, featuring equidistant and asymmetrical regions indicative of intermolecular interactions among cellular components post-biomass production, along with a higher concentration of phenolic compounds. Conversely, coatings based on S. platensis manifested agglomerate formation and empty spots, while those derived from S. obliquus displayed overlapping layers in distinct regions. Therefore, the incorporation of Chlorella sp. into coatings is recommended due to its macrostructured surface, which not only underscores intermolecular interactions within the biomass but also enhances the phenolic compound content, ultimately improving the efficacy of the edible coatings in preserving food quality. [ABSTRACT FROM AUTHOR]

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Microalgae can promote antibiotic removal, which has attracted growing attention. However, its synergistic removal performance with bacteria in antibiotic pollutants is still poorly understood. In this study, firstly, we selected two green algae (Dictyosphaerium sp. and Chlorella sp.) and exposed them to Enrofloxacin (ENR) to observe their extracellular polysaccharides (EPS) concentration dynamic and the removal of antibiotics. Secondly, EPS was extracted and added to in situ lake water (no algae) to investigate its combined effect with bacteria. The results indicate that both Dictyosphaerium sp. and Chlorella sp. exhibited high tolerance to ENR stress. When the biomass of microalgae was low, ENR could significantly stimulate algae to produce EPS. The removal rates of Dictyosphaerium sp. and Chlorella sp. were 15.8% and 10.5%, respectively. The addition of EPS can both alter the microbial community structure in the lake water and promote the removal of ENR. The LEfSe analysis showed that there were significant differences in the microbial marker taxa, which promoted the increase of special functional bacteria for decomposing ENR, between the EPS-added group and the control group. The EPS of Dictyosphaerium sp. increased the abundance of Moraxellaceae and Spirosomaceae, while the EPS of Chlorella sp. increased the abundance of Sphingomonadaceae and Microbacteriaceae. Under the synergistic effect, Chlorella sp. achieved a maximum removal rate of 24.2%, while Dictyosphaerium sp. achieved a maximum removal rate of 28.9%. Our study provides new insights into the removal performance and mechanism of antibiotics by freshwater microalgae in water bodies and contribute to the development of more effective water treatment strategies. [ABSTRACT FROM AUTHOR]

Background: Ferredoxin 1 (Fd1) is the main electron donor to hydrogenase (HydA) for generating molecular hydrogen (H2) in green microalgae. In order to obtain an increased H2 production, the Fd1 of Chlamydomonas reinhardtii (CrFd1, encoded by crfd1) was therefore overexpressed in Chlorella sp. DT (DT) in this study. Results: The coding region of crfd1 was constructed into the p121-crfd1 plasmid, which was also constructed with a resistance gene to the antibiotic geneticin (G418) as a selection marker. The p121-crfd1 plasmid was transformed into DT cells by electroporation. Observation of the crfd1 gene fragment in the genomic DNA of DT-crfd1 mutants by PCR indicated that the transgene was successfully transformed. Using western blotting, the overexpressed CrFd1 protein, with a molecular weight of about 14 kDa, was found in DT-crfd1 mutants of DT-crfd1-4, DT-crfd1-22, and DT-crfd1-23. Using an in vitro assay, the H2 production of DT-crfd1-4, DT-crfd1-22, and DT-crfd1-23 mutants was about 4.4-, 5.0-, and 3.8-fold higher, respectively, than the DT wild type (DT-WT). Using an in vivo assay, the H2 production of DT-crfd1-4, DT-crfd1-22, and DT-crfd1-23 mutants was about 1.3-, 1.4-, and 1.2-fold higher, respectively, than the DT-WT. Conclusions: The results suggested that heterologous overexpression of CrFd1 could enhance H2 production in DT-crfd1 mutants even though in vitro H2 production of DT-crfd1-22 mutant was up to 5-fold higher than the DT-WT.How to cite: Lin YJ, Chien LF. Hydrogen production in the Chlorella sp. DT mutants carrying heterologous electron donor ferredoxin 1 of Chlamydomonas reinhardtii. Electron J Biotechnol 2024;69. https://doi.org/10.1016/j.ejbt.2024.03.001.

Microalgae Chlorella sp. grows in the seas of South-East Sulawesi, Indonesia. However, information on the chemical and pharmaceutical aspects of this species from this region is still limited. Therefore, this research aims to explore the chemical contents and biological activities of Chlorella sp. The sample was collected from the Kali Biru and Nambo waters, Kendari. The microalgae were isolated by the agar plating technique and extracted by ethanol. Chemical content was analyzed by phytochemical screening, Liquid Chromatography-tandem Mass Spectroscopy (LC-MS/MS), Total Phenolics Content (TPC) and Total Flavonoids Contents (TFC). Biological activities evaluation includes antioxidant, toxicity, cytotoxicity and antimicrobial. Antioxidant potency was evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and ABTS (2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid). Toxicity and cytotoxicity properties were analyzed by BSLT (Brine Shrimp Lethality Test) and MTT (3-(4,5-Dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide) assays against Breast cancer (MCF-7) cell lines. Antimicrobial potency was tested towards E. coli, S. aureus and C. albicans. The result showed that ethanol extract of Chlorella sp. (EEC) contained phenolics, flavonoids, alkaloids and terpenoids/steroids which were supported by LC-MS/MS data, TPC and TFC with value 150.33 and 33.18 mgGAE.g-1 extract. Seven of ten identified major compounds caused this extract to have antioxidant and anticancer including xanthin, 1,1-Diethyl-3-oxo-2-triazanolate, Azelaic acid, ruspolinone, 6-keto prostaglandin F1a and glycol stearate. In general, the biological activity of EEC is less active than the positive controls for each assay. However, the EEC is more potential to be developed as antioxidant such as sunscreen and anticancer especially breast cancer with IC50 value 151-200 ppm and 100-500 ppm, respectively. [ABSTRACT FROM AUTHOR]

The addition of metal oxide nanoparticles (NPs) to microalgae cultures have become of great interest since they can directly and/or indirectly interact with microalgae resulting in enhanced production of biomass and high-value added products. The physicochemical characteristics of the NPs, i.e., crystal phase, can differently influence microalgae metabolism, thus the synthesis of optimal NPs is mandatory to improve the value of microalgae biomass.This study aimed at assessing the effect of Fe2O3 NPs on Chlorella spp. cultures with and without carbonate supplementation to confirm their beneficial effect. First, Fe2O3 NPs were synthetized and two different annealing temperatures were implemented, 450 °C (Fe2O3-450) and 1000 °C (Fe2O3-1000), to obtain Fe2O3 NPs with different crystal phases. The NPs crystal phase was analyzed by X-ray diffraction and the presence of the γ- and α- phases on both NPs were confirmed. However, the Fe2O3-450 NPs presented a higher content of the γ- phase. Subsequently, the effect of the crystal phase of Fe2O3 NPs was assessed in Chlorella spp. cultures. The addition of Fe2O3-1000 NPs resulted in inhibition of Chlorella spp. On the other hand, the addition of Fe2O3-450 NPs recorded the carbohydrate enhancements > 91% in Chlorella spp. cultures. The indirect effect of the synthetized NPs was assessed in microalgae cultures without carbonate supplementation and the same tendency was observed. This study proves that Fe2O3-450 NPs directly and indirectly interact with microalgae, and can be used as a strategy to produce high-value biomass even in environments without carbonate supplementation. [ABSTRACT FROM AUTHOR]

One of the organic fertilizers that has the potential to cultivate Chlorella sp. is the cow's rumen. To increase the nutrient content in the cow's rumen, the cow's rumen must be made into bokashi and enriched with chicken manure. This study aimed to determine the use of cow's rumen bokashi enriched with chicken manure at different doses on Chlorella sp cell density. The research design used was a Completely Randomized Design (CRD) with 5 treatments and 3 replications, namely P0 (2 g/L cow's rumen bokashi), P1 = 2 g/L cow's rumen bokashi enriched with 2.5 g/L chicken manure, P2 = 2 g/L cow's rumen bokashi enriched with 3.0 g/L chicken manure, P3 = 2 g/L cow's rumen bokashi enriched with 3.5 g/L chicken manure, and P4 = 2 g/L cow's rumen bokashi enriched with 4.0 g/L chicken manure. The results showed that the highest cell density of Chlorella sp. occurred in treatment P3 (i.e. 456.1 ± 15.1 × 104 cells/mL) and the highest specific growth rate occurred in treatment P0 (i.e. 0.20 ± 0.0/day). Nutrient levels in the culture medium are optimal for Chlorella sp., with nitrate ranging from 0.1375 to 0.2833 mg/L and phosphate ranging from 2.4889 to 2.8650 mg/L. From the results of this study, it can be concluded that the use of cow's rumen bokashi enriched with chicken manure had a very significant effect on cell density and specific growth rate of Chlorella sp. (P<0.01). [ABSTRACT FROM AUTHOR]

There is a great scientific curiosity to discover all environments sheltering microalgae, especially those with exceptional characteristics from coldest to hottest ones, the purpose remains to explore the potential of the native microalgae flora and the research for new bioactive compounds. This study aimed to isolate a polysaccharide-producing microalga from an extreme ecosystem and to evaluate its capacity to inhibit the α-d-glucosidase enzyme. Chlorella strain is isolated from hypersaline Lake in the Algerian desert. The exopolysaccharide extraction was performed by the concentration of free-cell supernatant in a rotary evaporator. The infrared analysis showed a characteristic footprint of carbohydrates with particular functional groups, such as sulfate. Gas chromatography–mass spectrometry has revealed a hetero-exopolysaccharide composed of galactose 35.75%, glucose 21.13%, xylose 16.81%, fructose 6.96%, arabinose 5.10%, and glucuronic acid 2.68%. The evaluation of the anti-hyperglycemic activity demonstrated a significant α-d-glucosidase inhibition of 80.94 ± 0.01% at 10 mg mL−1 with IC50 equal to 4.31 ± 0.20 mg mL−1. This study opens a vast prospect to use exopolysaccharides as natural nutraceutical or food additive. [ABSTRACT FROM AUTHOR]

Wastewater treatment with microalgae such as oxidation ditch algae reactor (ODAR) could reduce organic matter, however, the process might produce by-products that are toxic when dissolved in water. Effluent organic matter and algae organic matter are by-products of the microalgae process, that are released as well in ODAR system. The presence of these compounds in water can be a precursor for the formation of disinfection by-products (DBPs). The aim of this study is to determine the characteristics of effluent organic matter contained in domestic ODAR using the microalgae Chlorella sp. under variations of oxic and oxic-anoxic conditions. Novelty of this study is oxidation ditch combined with microalgae and the effect of aeration and intermittent aeration in the quality of wastewater effluent. Microalgae were applied in ODAR under oxic for 24 hours of aeration and oxic-anoxic through a brush aerator on for 7 hours and off for 3 hours with a ratio of waste volume to microalgae 1:1 with sampling time up to 5 hours. The results showed that BOD concentration tends to decrease up to 45% and 67% for oxic-anoxic and oxic, respectively. The UV254 value increased up to 110% and 147% for oxic-anoxic and oxic, respectively. Further, fluorescence excitation-emission matrix (FEEM) analysis identified the changing of four organic fractions as measured by the fluorescence regional index (FRI). The results indicate a decrease of aromatic protein-like significantly up to 62% and a decrease in soluble microbial products up to 30%. While humic acid-like and fulvic acid-like tends to increase by about 25-29% and 44-46%. [ABSTRACT FROM AUTHOR]

Chlorella has become one of the most studied and produced microalgae, with Spirulina among the hundreds of species since the beginning of microalgal biotechnology. The growth performance of microalgae and the biochemical composition of the biomass may also vary significantly by strain. Therefore, it is thought that searching for new strains from aquatic environments is important in providing the most suitable microalgae for production. An isolated strain from Daday Stream was cultured in the laboratory at Kastamonu University. BG-11 was used as a medium, and CO2 from the air was used as a carbon source in the experiments. The initial cell number was arranged to 1.0×106 cells mL-1, and the highest cell number was found on the 17th day as 40.52×106 cells mL-1. Chlorophyll a and carotenoids were determined at the end of the experiment and were found as 3.48±0.08 µg mL-1 and 1.16±0.02 µg mL-1, respectively. Total lipid amount and fatty acid composition analysis were also conducted at the end of the study. According to the analyses, the lipid content of Chlorella sp. was found to be 15.37±0.00% (w/w). SSFA (saturated fatty acid), SMUFA (monounsaturated fatty acid), and SPUFA (polyunsaturated fatty acid) ratios were calculated to be 31.30±1.21%, 4.99±0.34% and 63.71±2.65%, respectively. [ABSTRACT FROM AUTHOR]

IntroductionThe microalga Chlorella sp. NeZha, recently isolated from a balcony environment, shows significant adaptability across various salinity conditions, including seawater (SeaW), freshwater (FreshW), and high salinity levels (45‰). This study investigates its potential for sustainable aquaculture and biotechnological applications.MethodsMorphological and genetic identification were conducted using optical microscopy and DNA sequencing. The microalga was cultivated in a 400 L outdoor photobioreactor, and its biochemical composition, including chlorophyll a, carbohydrate, protein, and lipid content, was analyzed. Its compatibility with zooplankton and growth in aquaculture wastewater were also evaluated.ResultsChlorella sp. NeZha produced chlorophyll a at concentrations exceeding seaweed and Spirulina by 10- and 5-fold, respectively, with a dry weight chlorophyll a content of 34.25 mg/g and 25 pg./cell. The microalga also contained carbohydrate (~33%), protein (~20%), and lipids (~14%). It was compatible with zooplankton species, such as rotifers and brine shrimp, and showed promising growth in aquaculture wastewater.DiscussionThe findings suggest that Chlorella sp. NeZha is a viable candidate for sustainable aquaculture and biotechnological applications, offering high nutritional value and environmental resilience. Its adaptability to diverse salinity conditions and ability to thrive in wastewater highlight its potential for bioremediation and use as feedstock for zooplankton. Further research is recommended to optimize its cultivation and explore broader applications.

Cold climate ecosystems hint the researchers to discover economically native cold-adapted strains, which can tolerate temperature fluctuations in outdoor large-scale cultivation for producing lipids as biofuel or for nutritional applications. Cheshmeh-Sabz Lake (Iran) was screened in winter. The lake water was sampled at 5 °C and three strains of Scenedesmus sp. (dominant in BG-11), Ankistrodesmus sp. (dominant in WC), and Chlorella sp. (dominant in BBM) were identified using molecular methods. Strains' growth parameters, lipid content, and lipid productivity were also investigated at 8 and 25 °C. Scenedesmus sp. had the most biomass productivity (~ 0.54 ± 0.001 g/L*d) with no significant difference at 8 and 25 °C and demonstrated the highest amount of lipid productivity at 25 °C (9.43 ± 1.05 g/L*d). Scenedesmus sp. produced the highest percentage of α-linolenic acid at 15 and 25 °C (10.96 ± 1.5% and 11.07 ± 0.31%, respectively) among the strains. There was no significant difference for palmitic acid content at 8, 15, and 25 °C (41.05 ± 5.2, 38.48 ± 4.25, and 39.82 ± 1.58% respectively). Biomass productivity decreased in Ankistrodesmus sp. and Chlorella sp. at 8 °C in comparison to that of 25 °C (~ 86% and ~ 34% decrease, respectively). Ankistrodesmus sp. produced the highest proportion of α-linolenic acid at 8 °C (9.98 ± 0.10%). The highest percentage of palmitic acid was observed in Chlorella at 25 °C (44.41 ± 7.56%). Based on the results, Scenedesmus sp. is the proper choice for outdoor cultivation at different seasons due to its relatively high biomass productivity and the specific growth rate in low and high temperatures (8 and 25 °C). [ABSTRACT FROM AUTHOR]

Natural colorants play a crucial role in food product development and improvement of health. Microalga Chlorella sp. is one of the sources of natural colorant. In this study, different concentrations of microalga Chlorella sp. (0.5, 1, and 2%) were added to Puto as coloring agents to evaluate its sensory properties. Pigments such as chlorophyll a and total carotenoid quantities of Chlorella powder and the experimental group were also investigated. It was found that the natural colorant Chlorella sp. at all levels of concentrations did not affect the color properties (p≥0.05) of the Puto products. However, the smell and texture of Puto differed significantly (p≤0.05) when 2% Chlorella sp. was incorporated. The study also found that the 0.5% and 1% amounts of Chlorella sp. component did not significantly affect (p≥0.05) the Puto’s taste and overall acceptability. However, the 2% level of Chlorella sp. significantly decreased both overall acceptability and taste attributes. Moreover, Chlorella sp. powder constituted 4004.79±119.1 µg g-1 chlorophyll a and 1442.67±74.41 µg g-1 total carotenoids. Chlorophyll a amounts in experimental groups varied from 14.34±0.49 µg g-1 to 54.06±1.71 µg g-1 while total carotenoids amounts were found ranging from 5.59±0.37 µg g-1 and 18.06±0.66 µg g-1 . Puto used these biomasses at a concentration of 0.5%, 1%, and 2% as natural green colorants. However, chlorophyll a and carotenoid pigments level at 2% Chlorella sp. were not tolerable for the production of Puto. Hence, the Chlorella sp. biomass at 0.5% and 1% would be suitable for use as a natural colorant in the Filipino delicacy Puto. [ABSTRACT FROM AUTHOR]

The present study evaluated the effects of heavy metals, viz., lead, mercury, and cadmium, on growth, chlorophyll a, b, c, carotenoids, and PUFA content of marine microalgae Chlorella sp. and Cylindrotheca fusiformis. At 96-h exposure, the IC50 values for Hg2+, Pb2+, and Cd2+ were 0.85 mg/L, 2.4 mg/L, and 5.3 mg/L respectively, in Chlorella sp. In C. fusiformis, IC50 values for Hg2+, Pb2+, and Cd2+ were 0.5 mg/L, 1.2 mg/L, and 3 mg/L respectively. The pigment contents of both microalgae were significantly affected upon heavy metal exposure. In Chlorella sp. and C. fusiformis, the exposed concentrations of Hg2+ averagely decreased the PUFA content by 76.34% and 78.68%, respectively. Similarly, Pb2+-exposed concentrations resulted in 54.50% and 82.64% average reductions in PUFA content of Chlorella sp. and C. fusiformis, respectively. Cd2+-exposed concentrations showed 32.58% and 40.54% average reduction in PUFA content of Chlorella sp. and C. fusiformis, respectively. Among the environmental stress conditions, the dark treatment has increased total PUFA content by 6.63% in Chlorella sp. and 3.92% in C. fusiformis. It was observed that the 50% nitrogen starvation (two-stage) significantly improved the PUFA production from 26.47 ± 6.55% to 40.92 ± 10.74% in Chlorella sp. and from 11.23 ± 5.01 to 32.8 ± 14.17% in C. fusiformis. The toxicity for both microalgae was followed in the order Hg2+ > Pb2+ > Cd2+. Among the two species, Chlorella sp. has shown a high tolerance to heavy metals and can be effectively utilized in PUFA production. [ABSTRACT FROM AUTHOR]

In this study, we investigated the use of functionalized deep eutectic solvents (DESs) as a medium for CO2 capture integrated with CO2 desorption and biofixation in microalgal culture, as an approach for carbon capture, utilization, and storage (CCUS). The newly devised DES formulation—comprising choline chloride, ethylene glycol, and monoethanolamine—demonstrated a significant advancement in CO2 absorption capacity compared with conventional solvents. Effective CO2 desorption from the solvent was also achieved, recovering nearly 90% of the captured CO2. We then examined the application of the functionalized DESs to promote microalgal cultivation using a Chlorella sp. strain. The experimental results indicated that microalgae exposed to DES-desorbed CO2 exhibited heightened growth rates and enhanced biomass production, signifying the potential of DES-driven CO2 capture for sustainable microalgal biomass cultivation. This research contributes to the growing field of CCUS strategies, offering an avenue for efficient CO2 capture and conversion into valuable biomasses, thereby contributing to both environmental sustainability and bioresource use. [ABSTRACT FROM AUTHOR]

Microalgae are powerful source for nutritionally valuable components as proteins, carbohydrates and especially unsaturated fatty acids. Microalgae may be employed in pharmaceutical, food, cosmetic, health industries, and biofuels. In this study for looking at high-level unsaturated fatty acids species, from 31 strains, by comparing growth curves, the best strain with a high growth rate and lipid content was selected by red Nile staining. It was determined by molecular identification that this strain belongs to the genus Chlorella sp. and is deposited into the Agricultural Biotechnology Research Institute of Iran Culture collection with culture collection number ABRIICC 30,041. Biomass analysis after growth optimization by response surface methodology showed that the selected strain had a specific growth rate of 0.216 ± 0.008 d−1, biomass productivity of 142.58 ± 4.41 mg/Ld, and lipid content of 13.9 ± 0.26% with a high level of unsaturated fatty acids of 53.15%. It also included 51.3 ± 0.53% protein with a very high quality essential amino acids of 40.36%, the most lysine (8.77%) and arginine (13.31%) has been reported until now, and 26.9 ± 0.23% carbohydrates in photoautotroph condition. By MTT assay, there is no effect of cytotoxicity. This research introduces a potent native strain comparable with commercial strains that can be a hopeful source for food supplements and valuable bioactive ingredients in functional foods. [ABSTRACT FROM AUTHOR]

The efficient management and treatment of pharmaceutical industry wastewater (PIWW) have become a serious environmental issue due to its high toxicity. To overcome this problem, the present study deals with the phycoremediation of PIWW using Chlorella vulgaris microalga isolated from the Ganga River at Haridwar, India. For this, response surface methodology (RSM) and artificial neural network (ANN) tools were used to identify the best reduction of total phosphorus (TP) and total Kjeldahl's nitrogen (TKN) based pollutants along with the lipid production efficiency of C. vulgaris. Three different concentrations of pharmaceutical wastewater (0, 50, and 100%), operating temperatures (20, 25, and 30 °C), and light intensity (2000, 3000, and 4000 lx) were used to design the phycoremediation experiments having 6:18 h of dark/light period and reactor functional volume of 15L. Findings revealed that C. vulgaris was good enough to remove maximum TP (90.35%), TKN (83.55%) along 20.88% of lipid yield at 25.62 °C temperature, 60.73% PIWW concentration, and 4000 lx of light intensity, respectively. Based on the model performance and validation results, ANN showed more accuracy as compared to the RSM tool. Therefore, the findings of this study showed that C. vulgaris is capable of treating PIWW efficiently along with significant production of lipid content which can further be used in various applications including biofuel production. [ABSTRACT FROM AUTHOR]

Microalgae are highly studied microorganisms for the production of high-value products due to their high content of proteins, lipids, carbohydrates, and chlorophyll. These compounds are refined to obtain profitable industrial products. This article analyzes the lipid production of Chlorella sp. biomass, considering 18 scenarios for its production, with 9 of these being partially supplemented with swine wastewater. A 1 ha area was considered for biomass cultivation, primary and secondary biomass harvesting, and lipid extraction. Using simulation in the software SuperPro Designer v10, parameters such as CO2 capture (from a thermoelectric power plant), freshwater consumption, wastewater consumption, energy consumption, and unit production cost were evaluated. The results show that the production cost is high, ranging from 836.9 US $/kg to 1131.5 US $/kg of produced lipids, with a maximum CO2 capture of 454 kg of CO2/kg of lipids. The use of wastewater reduces the production cost by approximately 10%. The evaluation of technical and economic parameters allows us to identify bottlenecks and implement strategies to reduce production costs. [ABSTRACT FROM AUTHOR]

In this study, we investigated the use of functionalized deep eutectic solvents (DESs) as a medium for CO2 capture integrated with CO2 desorption and biofixation in microalgal culture, as an approach for carbon capture, utilization, and storage (CCUS). The newly devised DES formulation—comprising choline chloride, ethylene glycol, and monoethanolamine—demonstrated a significant advancement in CO2 absorption capacity compared with conventional solvents. Effective CO2 desorption from the solvent was also achieved, recovering nearly 90% of the captured CO2. We then examined the application of the functionalized DESs to promote microalgal cultivation using a Chlorella sp. strain. The experimental results indicated that microalgae exposed to DES-desorbed CO2 exhibited heightened growth rates and enhanced biomass production, signifying the potential of DES-driven CO2 capture for sustainable microalgal biomass cultivation. This research contributes to the growing field of CCUS strategies, offering an avenue for efficient CO2 capture and conversion into valuable biomasses, thereby contributing to both environmental sustainability and bioresource use.

Dünya nüfusunun hızla artmasıyla birlikte enerji krizleri, iklim değişiklikleri, küresel ısınma, gıda yetersizliği ve dengesiz beslenme gibi sorunların beraberinde geleceği tahmin edilmektedir. Bu sorunların öngörülmesiyle birlikte, insanoğlu alternatif gıda kaynaklarına ihtiyaç duymaya başlamıştır. Yüksek besin içerikleri, sağlığa olumlu etkileri ve sürdürülebilirlikleri ile ilgi gören algler, fonksiyonel gıda olmaya aday ürünler olarak değerlendirilmektedir. Deniz florasının yaklaşık %95’ini oluşturan algler, acı, tatlı, tuzlu, alkali sularda ve topraklarda yetişebilmektedir. Ekonomik ve kolay üretime sahip olmaları nedeniyle gelecekte besin ihtiyacının karşılanabileceği kaynaklardır. İmmünomodülatör, antibakteriyel, antioksidan gibi fazla sayıda sağlığa faydalı etkileri ile Alzheimer hastalığı, alerjik hastalıklar, kardiyovasküler hastalıklar gibi birçok hastalığı önleyici etkilere de sahiptir. Özellikle proteinler, lipitler, çoklu doymamış yağ asitleri (PUFA), polisakkaritler, pigmentler ve polifenoller bakımından zengin olan algler, mikroalgler ve makroalgler olmak üzere ikiye ayrılmaktadır. Bu derleme çalışmasında, mikroalglerden olan Spirulina sp. ve Chlorella sp. hakkında literatür taraması yapılmış, besin içeriklerine, sağlık etkilerine ve gıda endüstrisinde yapılan zenginleştirme çalışmalarına kısaca değinilmiştir.

Optimization can streamline experimental trials by evaluating the parameters and parameter interactions used as the basis for a more optimal downstream process. This study aims to optimize the microwave-assisted pyrolysis process in producing bio-oil from microalgae using response surface methodology (RSM) complemented by an investigation of the reaction mechanisms. A number of key parameters (microwave power, absorbent-to-microalgae ratio, and pyrolysis time) were fine-tuned using a face-centered central composite design. The result showed that microwave technology in slow pyrolysis could produce the bio-oil from microalgae 12 times shorter than conventional heating and quadratic model with a high precision (R2 = 0.9832, R2adj = 0.9616) from RSM optimization in predicting experimental values yielded a peak bio-oil yield of 19.11% under specific conditions: 20 min of pyrolysis time, a 0.19 (w/w) microwave absorber to microalgae ratio, and 583 W power. As the complex biomass, the reaction mechanism in chlorella sp. towards this technology including decarboxylation, decarbonylation, dehydration, cracking, deoxygenation, and esterification was proved in GCMS analysis, revealing the presence of key functional groups such as aliphatic, aromatics, alcohols, nitrogenous compounds, fatty acid methyl esters (FAME) and Polycyclic Aromatics Hydrocarbons (PAHs).

This paper presents the data on growth performance of marine Chlorella sp. cultured in different cost-effective media including cow dung, cow urine, poultry litter, compost, NPK (nitrogen, phosphorus, and potassium), and UTR (Urea, TSP, and red potash). Growth curve of Chlorella sp. was determined at 5 mg of cow dung, poultry litter, compost, NPK, UTR and 5 µL of cow urine per 350 ml sea water (25 ppt) to identify the onset of stationary phase. Further four media among these were selected to continue the experiment at 8 mg and 11 mg of concentration. The higher cell densities were 4.21 × 106 and 4.18 × 106 cells/mL for NPK at 8 mg and 11 mg of concentration on 6th and 5th day, respectively. Cow dung with an 11 mg of concentration exhibited 2.67 × 106 cells/mL on the 3rd day, which is around 1.5 times greater than the highest growth in the same concentration of poultry litter. Chlorella sp. had a higher cell density in NPK media than in other media, however it was discarded since it is inorganic and costly. Due to the low cell density in cow urine media and the prolonged stationary phase in poultry litter media, the focus of the subsequent study was then placed on cow dung media. The data will contribute to the selection of locally available and cost-effective culture media by determining the stationary phases for specific microalgal species which will replace the costly and labor-intensive commercial media.

Algal Organic Matter (AOM) is derived from the dissolved organic matter composition of the algal species being observed. In this study, excitation–emission fluorescence spectroscopy was used to determine Chlorella sp.'s AOM and pigment characteristics in varying algal biomass concentrations. The AOM and pigment characteristics were observed at 400–600 nm and 600–800 nm fluorescence emission, respectively, with an excitation spectrum of 300–450 nm. F450/680 was computed based on the ratio between the dissolved organic matter contribution at 450 nm and chlorophyll-a at 680 nm. F450/680 positively correlated with algal biomass (r = 0.96) at an excitation wavelength of 405 nm. This study is a good reference for those interested in algal biomass estimation and production in natural waters. [ABSTRACT FROM AUTHOR]

Wastewater treatment plants produce solid and semi-solid sludge, which treatment minimises secondary environmental pollution because of wastewater treatment and obtaining new bioproducts. For this reason, in this paper, the co-pyrolysis of biogenic biomasses recovered from a biological reactor with immobilised fungal and bacterial biomass and a tertiary reactor with Chlorella sp. used for dye-contaminated wastewater treatment was carried out. Biogenic biomasses mixed with pine bark allowed the production and characterisation of two types of biochar. The raw material and biochar were on the "in vitro" germination of Lolium sp. seeds, followed by adsorption studies for malachite green (MG) dye using the raw material and the biochar. Results showed that using 60 mg L−1 of a cationic coagulant at pH 6.5 allowed for the recovery of more than 90% of the microalgae after 50 min of processing. Two biochar resulted: BC300, at pH 5.08 ± 0.08 and BC500, at pH 6.78 ± 0.01. The raw material and both biochars were co-inoculated with growth-promoting bacteria; their viabilities ranged from 1.7 × 106 ± 1.0 × 101 to 7.5 × 108 ± 6.0 × 102 CFU g−1 for total heterotrophic, nitrogen-fixing and phosphate-solubilising bacteria. Re-use tests on Lolium sp. seed germination showed that with the post-coagulation effluent, the germination was 100%, while with the biochar, with and without beneficial bacteria, the germination was 98 and 99%, respectively. Finally, BC500 adsorbed the highest percentage of malachite green at pH 4.0, obtaining qecal values of 0.5249 mg g−1 (R2: 0.9875) with the pseudo-second-order model. [ABSTRACT FROM AUTHOR]

Oil palm liquid waste contains N (nitrate) and P (phosphate) which can be utilized for the growth of microalgae. Utilization of palm oil liquid waste using microalgae has been widely carried out. One of the microalgae that has potential as phycoremediation is Chlorella sp. Factors that affect the growth of Chlorella sp. cells, are the intensity of light and nutrients. This study used the same concentration of palm oil wastewater, namely 25% with different light intensities. A research aims to determine the best light intensity in producing Chlorella sp., carried out in December 2022-January 2023. The method used is the experimental method with Completely Randomized Design (CRD) with 4 treatments, namely: light intensity 6 Lux, light intensity 1443 Lux, light intensity 2748 Lux, and light intensity 3171 Lux. Water quality parameters measured were cell abundance (once/two days), Chlorella sp. biomass (in the exponential phase), temperature, pH, dissolved oxygen (DO) (once/two days) and nitrate, phosphate (at the beginning, exponential phase and at the end). study). The results showed that the abundance of cells during this study ranged from 0.70 x 106 - 1.98 x 106 cells/ml and the biomass ranged from 0.11-0.29 g/L. The results of water quality measurements are temperatures ranging from 27℃-31.30℃, pH ranging from 7-8, dissolved oxygen 6.06 mg/L-8.66 mg/L, nitrate concentrations were 9.21 mg/L-9.27 mg/L and phosphate concentrations 3.19 mg/L-3.26 mg/L. Water quality parameters in this study such as temperature, pH, dissolved oxygen (DO), nitrate and phosphate are still classified as capable of supporting growth Chlorella sp. Based on the data above the best light intensity for culture Chlorella sp., is 3171 Lux. [ABSTRACT FROM AUTHOR]

In the context of global demand for carbon reduction, the formation of inorganic carbon (IC) in the wastewater from oil flooding becomes a potential threat. In this study, Chlorella sp. and Fusarium sp. were used to assemble a fungal-algal pellet to degrade polyacrylamide (PAM) and fix IC in synthetic oil-flooding wastewater. The results showed that the combination of Chlorella sp. and Fusarium sp. was more effective at degrading PAM and removing carbon than a monoculture. With PAM as the sole nitrogen source, the degradation of PAM by the consortium was enhanced up to 35.17 ± 0.86% and 21.63 ± 2.23% compared with the monocultures of fungi or microalgae, respectively. The degradation of the consortium was significantly enhanced by the addition of an external nitrogen source by up to 27.17 ± 2.27% and 22.86 ± 2.4% compared with the monoculture of fungi or microalgae, respectively. This may depend on the effect of synergy between the two species. For the removal of IC from the water, the removal efficiency of the consortium was higher than that of the microalgae by 38.5 ± 0.08%, which may be attributed to the ability of the fungi to aid in the adsorption of nutrients and its assimilation by the microalgae. Therefore, the Fusarium-Chlorella consortium can effectively degrade PAM, while simultaneously fixing carbon, which provides a feasible scheme for the treatment and carbon neutralization of the wastewater that contains PAM. [ABSTRACT FROM AUTHOR]

In the treatment of wastewater containing only chemical oxygen demand (COD) by Chlorella sp., the cell activity and proliferation ability of Chlorella sp. decreased with the culture time, which affected the removal of COD in wastewater. To solve these problems, the Chlorella sp.–natural microorganism symbiosis system was prepared. The system was used to explore how natural microorganisms affect the cell activity and the proliferation ability of Chlorella sp. in wastewater. In the treatment of COD by Chlorella sp., the removal rate of COD decreased from 45.47% to 28.88%, with a decrease in the cell activity and proliferation ability of Chlorella sp. In the Chlorella sp.–natural microorganism symbiotic system, the removal rate of COD reached 45.75%. With the introduction of natural microorganisms, the circulation of CO2 and O2 between Chlorella sp. and natural microorganisms promoted photosynthesis and respiration, which enhanced the cell activity of Chlorella sp. Under the condition that the dosage of natural microorganisms was between 1% and 6%, the concentration of Chlorella sp. was close to the logarithmic growth phase, which maintained the proliferation ability of Chlorella sp. At the same time, the natural microorganisms grew and proliferated in wastewater containing only COD through preying on Chlorella sp. [ABSTRACT FROM AUTHOR]

Conventionally, microalgal lipid extraction uses volatile organic compounds as an extraction solvent. However, these solvents are harmful to human and environmental health. Therefore, this study evaluated the feasibility of alternative green solvents, namely, ethanol, dimethyl carbonate (DMC), cyclopentyl methyl ether (CPME), and 2-methyltetrahydrofuran (2-MeTHF) in lipid extraction from Chlorella sp. via ultrasound-assisted extraction (UAE). This study indicated that extraction parameters, such as ethanol-to-2-MeTHF ratio, solvent-to-biomass ratio, temperature, and time, significantly affected the crude lipid yield (P < 0.05). The highest crude lipid yield of 25.05 ± 0.924% was achieved using ethanol–2-MeTHF mixture (2:1, v/v) with a solvent-to-biomass ratio of 20:1 (v/w) at 60 °C for 25 min accompanying 100 W and 40 kHz. Ethanol-2-MeTHF-extracted lipids showed dominance in linoleic acid, α-linolenic acid, and palmitic acid. Overall this findings supported UAE using ethanol and 2-MeTHF as extraction solvents is a promising green alternative to conventional solvent extraction of lipids from microalgae. [ABSTRACT FROM AUTHOR]

The aim of the present study is to grow microalgae to remove CO2 from a stripping column as well as macronutrients from a biogas digester effluent. In mixotrophic conditions, non-sterilized and sterilized chicken farm biogas effluents were used to cultivate Chlorella sp. Endogenous bacteria in the wastewater had no effect on the rate of algal growth. Continuous experiments by feeding wastewater at COD loadings of 1.89–6.30 kg COD/m3/day were also conducted. The CO2 removal efficiency was in the range of 13–39%. Chlorella sp. showed the nutrient removal efficiency of COD, TN, and TP was 44%, 30%, and 54%, respectively. CO2-rich off-gas from a biogas upgrading system's stripping column can be used to boost algal growth in biogas digester effluent. The CO2 can be extracted in part, but the wastewater can be treated simultaneously. Consequently, this study established that an integrated system is economically viable. [ABSTRACT FROM AUTHOR]

Grey water contains organic matter that is directly disposed to the environment without any treatment previously, will cause pollution and impacting life in the water. Treatment that can be done is using microorganisms. One of its kind is the microalgae Chlorella sp. which utilizes organic matter as a source of nutrients for its growth. In this study, the Kaldness 1 (K1) bio carrier was added as a medium for attaching microorganisms using the Sequencing Batch Biofilm Reactor (SBBR) process. The research objectives were (1) to know the maximum number of Chlorella sp. both attached and suspended in the Sequencing Batch Biofilm Reactor (SBBR), (2) to obtain the best cycle time and stabilization time in the removal of COD, Ammonia, and MLSS in grey water. The research was conducted by varying the stabilization time (1.5; 2 and 2.5 hours) in each cycle for four cycles with a constant variation of charging time 30 minutes, reaction 120 minutes, 45 minutes, separation 45 minutes, and carried out with four cycles, stirring speed at 60 rpm, the concentration of algae suspension in SBBR was 25% and the volume of Kaldness K1 medium was 20%. The results showed the number of microalgae cells Chlorella sp. was suspended and attached to 1.85 x 106 and 1.46 x 106 cells/ml. The best removal of COD, ammonia, and MLSS was found in the stabilization time variation of 1.5 hours in 4 cycles with a removal efficiency of 84% and 76%, respectively, and an increase in the concentration of suspended and attached MLSS by 4780 mg/l and 4720 mg/l. It can be concluded that the faster stabilization time, the more removal efficient will be.

Chlorella sp. microalgae is a potential source of natural antioxidants and other bioactive compounds used in the food and pharmaceutical industries. Ultrasound pretreatments followed by enzymolysis are widely used to improve the functional properties of biological materials. This work aimed to investigate the effects of ultrasound pretreatments followed by bromelain hydrolysis on the proteins, phenolic content, and antioxidant activity of Chlorella sp. crude extract. The experimental design for the study involved two factors: ultrasound pretreatment time (0, 5, and 10 min) and bromelain hydrolysis time (0, 2, 4, and 6 hours). The protein was measured using Lowry assay while the total phenolic content was measured using a Folin–Ciocalteu assay. The highest protein content (7.09 ± 0.44 mg/mL) and phenolic concentrations (0.28 ± 0.01 ìg/mL) were obtained at 5 min ultrasound pretreatment and 6 hours enzymolysis. For antioxidant activity, 5 min ultrasound pretreatment followed by 4 hours of enzymolysis resulted in the highest DPPH (1,1-diphenyl-2-picrylhydrazyl radical) inhibitory activity (81.74%). Meanwhile, ultrasound pretreatment for 10 min followed by 6 hours of enzymolysis resulted in the highest ABTS (2,20 azinobis-(3-ethylbenzthiazoline-6-sulfonic acid) inhibitory activity (94.10%). This study showed that variation in ultrasound pretreatments followed by bromelain hydrolysis could be used to improve the protein content, phenolic content, and antioxidant activity of Chlorella sp. crude extract.

In the realmof applied phycology, algal physiology, and biochemistry publications, the absence of proper identification and documentation of microalgae is a common concern. This poses a significant challenge for non-specialists who struggle to identify numerous eukaryotic microalgae. However, a promising solution lies in employing an appropriate DNA barcoding technique and establishing comprehensive databases of reference sequences. To address this issue, we conducted a study focusing on the molecular characterization and strain identification of Tetraselmis and Chlorella species, utilizing the internal transcribed spacer (ITS) barcode approach. By analyzing the full nuclear ITS region through the Sanger sequencing approach, we obtained ITS barcodes that were subsequently compared with other ITS sequences of various Tetraselmis and Chlorella species. To ensure the reliability of our identification procedure, we conducted a meticulous comparison of the DNA alignment, constructed a phylogenetic tree, and determined the percentage of identical nucleotides. The findings of our study reveal the significant value of the ITS genomic region as a tool for distinguishing and identifying morphologically similar chlorophyta. Moreover, our results demonstrate that both the ITS1 and ITS2 regions are capable of effectively discriminating isolates from one another; however, ITS2 is preferred due to its greater intraspecific variation. These results underscore the indispensability of employing ITS barcoding in microalgae identification, highlighting the limitations of relying solely on morphological characterization. [ABSTRACT FROM AUTHOR]

Microalgae provide a potential alternative for high-value products. Integrating microalgae into the landfill leachate valorization process gives the opportunity to save water sources for biomass production. The aim of this study is to investigate the ability of landfill leachate to support microalgal biomass production and to explore how leachate affects the fatty acid and lipid content of microalgae. The wild "Chlorella sp." strain was isolated from a Tunisian natural lake and experimented in standard culture medium (Bold) as well as in different rates of landfill leachate. Results revealed that the leachate rate of 10% produced the highest amount of biomass (2.6 g L−1), which was significantly higher than Bold's medium. The final percentage of lipids recorded was 53% and 78% in Bold's medium and in leachate, respectively. Lipid productivity was stimulated 11 times more than obtained in Bold's medium with 823 mg L−1 d−1 in 10% leachate and 69.6 mg L−1 d−1 for Bold's medium. Characterization of the lipid extract using gas chromatography with a flame ionization detector (GC-FID) showed that around 90% of the total lipid content appeared mainly composed with saturated fatty acids such as palmitic acid (C16:0) and linoleic acid (C18:2) indicating a good quality of biodiesel. The leachate rate of 10% promotes the oleic, linoleic and linolenic acids known as omega 9, 6 and omega 3, respectively, by increasing its production to 10, 37 and 4%, respectively, while it was about only 5, 30 and 2%, respectively, in Bold's culture medium. It could be concluded that the Chlorella strain isolated from natural lake performs as a good tolerant organism to landfill leachate, and its culture in this effluent could be a potential source for lipid and biodiesel production. Using landfill leachate as a culture medium gives the opportunity to save water sources for microalgal biomass production. Growth and lipid production performances of a wild Chlorella sp.microalgae using landfill leachate as a culture medium [ABSTRACT FROM AUTHOR]

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Chronic diabetic wound remains a critical challenge suffering from the complicated negative microenvironments, such as high-glucose, excessive reactive oxygen species (ROS), hypoxia and malnutrition. Unfortunately, few strategies have been developed to ameliorate the multiple microenvironments simultaneously. In this study, Chlorella sp. (Chlorella) hydrogels were prepared against diabetic wounds. In vitro experiments demonstrated that living Chlorella could produce dissolved oxygen by photosynthesis, actively consume glucose and deplete ROS with the inherent antioxidants, during the daytime. At night, Chlorella was inactivated in situ by chlorine dioxide with human-body harmless concentration to utilize its abundant contents. It was verified in vitro that the inactivated-Chlorella could supply nutrition, relieve inflammation and terminate the oxygen-consumption of Chlorella-respiration. The advantages of living Chlorella and its contents were integrated ingeniously. The abovementioned functions were proven to accelerate cell proliferation, migration and angiogenesis in vitro. Then, streptozotocin-induced diabetic mice were employed for further validation. The in vivo outcomes confirmed that Chlorella could ameliorate the undesirable microenvironments, including hypoxia, high-glucose, excessive-ROS and chronic inflammation, thereby synergistically promoting tissue regeneration. Given the results above, Chlorella is considered as a tailor-made therapeutic strategy for diabetic wound healing.

Two modes of electrochemical harvesting for microalgae were investigated in the current work. A sacrificial anode (aluminum) was used to study the electrocoagulation-flotation process, and a nonsacrificial anode (graphite) was used to investigate the electroflotation process. The study inspected the effect of chloride ions concentration and the interelectrode distance on the performance of the electrochemical harvesting processes. The results demonstrated that both electrodes achieved maximum harvesting efficiency with a 2 g/L NaCl concentration. Interestingly, by increasing the NaCl concentration to 5 g/L, the harvesting efficiency reduced dramatically to its lowest value. Generally, the energy consumption decreased with increasing of NaCl concentration. Moreover, the energy consumption achieved with aluminum anodes is lower than that achieved with graphite. However, by increasing the gap between the electrodes from 15 mm to 30 mm, the time required to achieve the maximum efficiency doubled, and energy consumption increased consequently.

Microalgae are considered natural alternatives to replace synthetic antioxidants. The extraction of polyphenols from Scenedesmus sp. and Chlorella sp. was optimized by employing a central composite design. The effect of solvent nature (ethanol, methanol, and ethyl acetate), extraction temperature (4–80 °C), and extraction time (0.1–4 h) were investigated with an ultrasound-assisted system. Total phenolic compound (TPC) extraction was higher at the combination of methanol, 4 °C, and 4 h for Scenedesmus and methanol, 80 °C, and 4 h for Chlorella. Microalgae were cultivated in BG11 and BG11 + 40% olive mill wastewater (OMUF) media. The extracts were analyzed for their total polyphenol content and antioxidant and antimicrobial activities. The estimation results of models and experimental results indicated a high consistency when cultivating microalgae in BG11 medium. Polyphenols extracted from microalgae cultured with 40% (OMUF) possess significantly high antioxidant and antimicrobial activities. Hence, Scenedesmus sp. and Chlorella sp. showed a capability to grow in the presence of ultrafiltered OMW and produce high added-value compounds. [ABSTRACT FROM AUTHOR]

Cultivation of microalgae using wastewater as nutrient resource is a promising strategy to reduce the microalgae biodiesel production cost and increase nutrient recovery in one step. However, the inhibitive effect of indigenous bacteria on microalgae could negatively affect microalgal growth. Thus, in this study, the effect of wastewater disinfection methods on the growth and biochemical composition of Chlorella sp. and the nutrient removal efficiency in cafeteria wastewater was evaluated. Results showed a significant increase in the microalgal density and a reduction in bacterial abundance in the disinfected wastewater. Moreover, chemical oxygen demand removal ranging from 83.53%-87.16% was achieved in 15-d incubation and complete removal of total nitrogen and total phosphorus was achieved after 6 d of incubation. The total carbohydrate, protein and fatty acid contents in the harvested biomass were 128.49-139.33, 43.24-56.14 and 17.34-23.58 mg·g-1 on dry weight basis, respectively. Palmitic acid, palmitoleic acid, stearic acid and oleic acid accounted for more than 90% of the total fatty acids in the biomass, indicating great potential as an alternative feedstock for biodiesel production. This study provides a simple and efficient disinfection strategy to enhance Chlorella sp. growth and biomass production for biodiesel production. [ABSTRACT FROM AUTHOR]

In the realm of applied phycology, algal physiology, and biochemistry publications, the absence of proper identification and documentation of microalgae is a common concern. This poses a significant challenge for non-specialists who struggle to identify numerous eukaryotic microalgae. However, a promising solution lies in employing an appropriate DNA barcoding technique and establishing comprehensive databases of reference sequences. To address this issue, we conducted a study focusing on the molecular characterization and strain identification of Tetraselmis and Chlorella species, utilizing the internal transcribed spacer (ITS) barcode approach. By analyzing the full nuclear ITS region through the Sanger sequencing approach, we obtained ITS barcodes that were subsequently compared with other ITS sequences of various Tetraselmis and Chlorella species. To ensure the reliability of our identification procedure, we conducted a meticulous comparison of the DNA alignment, constructed a phylogenetic tree, and determined the percentage of identical nucleotides. The findings of our study reveal the significant value of the ITS genomic region as a tool for distinguishing and identifying morphologically similar chlorophyta. Moreover, our results demonstrate that both the ITS1 and ITS2 regions are capable of effectively discriminating isolates from one another; however, ITS2 is preferred due to its greater intraspecific variation. These results underscore the indispensability of employing ITS barcoding in microalgae identification, highlighting the limitations of relying solely on morphological characterization.

Microwave-assisted enzymatic extraction (MAEE) was used for the separation of polysaccharides from micro-Chlorella. The extraction condition of MAEE was optimized by Box-Behnken design and response surface methodology. Results showed that the optimal condition for the extraction of Chlorella sp. crude polysaccharides (CSCP) was at 50°C for 2.3 h with 380 W of microwave power and 0.31% of enzyme dosage. Under the optimal extraction condition, the extraction yield of CSCP reached 0.72%. Similarly, the α-amylase modification conditions of the CSCP were also optimized, in which the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging rate was used as the response value. The scavenging rate of DPPH free radicals was 17.58% when enzyme dosage was 271 U/g at 51°C for 14 min. Moreover, the enzyme-modified CSCP presented a typical heteropolysaccharide mainly including glucose (48.84%), ribose (13.57%) and mannose (11.30%). MAEE used in this work achieved a high extraction yield of CSCP, which provides an efficient method for the extraction of CSCP from Chlorella sp.

Digestates from different anaerobic digesters are promising substrates for microalgal culture, leading to effective wastewater treatment and the production of microalgal biomass. However, further detailed research is needed before they can be used on a large scale. The aims of this study were to investigate the culture of Chlorella sp. in DigestateM from anaerobic fermentation of brewer’s grains and brewery wastewater (BWW) and to explore the potential use of the biomass produced under different experimental conditions, including diverse cultivation modes and dilution ratios. Cultivation in DigestateM initiated from 10% (v/v) loading, with 20% BWW, obtained maximum biomass production, reaching 1.36 g L−1 that was 0.27g L−1 higher than 1.09 g L−1 of BG11. In terms of DigestateM remediation, the maximum removal of ammonia nitrogen (NH4+-N), chemical oxygen demand, total nitrogen, and total phosphorus reached 98.20%, 89.98%, 86.98%, and 71.86%, respectively. The maximum lipid, carbohydrate, and protein contents were 41.60%, 32.44%, and 27.72%, respectively. The growth of Chlorella sp. may be inhibited when the Y(II)–Fv/Fm ratio is less than 0.4.