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1.
Ecotoxicol Environ Saf ; 209: 111818, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33360284

RESUMO

Estrogens are among the most concerned emerging contaminants in the wastewater treatment effluent due to their sexual disruption in aquatic wildlife. The use of microalgae for secondary wastewater effluent polishing is a promising approach due to the economic benefit and value-added products. In this study, three microalgae species, including Selenastrum capricornutum, Scenedesmus quadricauda and Chlorella vulgaris were selected to conduct batch experiments to examine important mechanisms, especially the role of algal extracellular organic matter (AEOM) on two selected estrogens (17ß-estradiol, E2 and 17α-ethynylestradiol, EE2) removal. Results showed that estrogens could not be significantly degraded under visible light irradiation and adsorption of estrogens by microalgae was negligible. All three living microalgae cultures have ability to remove E2 and EE2, and Selenastrum capricornutum showed the highest E2 and EE2 removal efficiency of 91% and 83%, respectively, corresponding to the reduction of predicted estrogenic activity of 86%. AEOM from three microalgae cultures could induce photodegradation of estrogens, and AEOM from Selenastrum capricornutum and Chlorella vulgaris achieved 100% of E2 and EE2 removal under visible light irradiation. Fluorescence excitation-emission matrix spectroscopy identified humic/fulvic-like substances in AEOM from three microalgae cultures, which might be responsible for inducing the indirect photolysis of E2 and EE2. Therefore, in the living microalgae cultures, the major estrogens removal mechanisms should include biotransformation as well as AEOM meditated photocatalytic degradation. Since removal rates through photodegradation could be faster than biotransformation, the AEOM mediated photocatalytic degradation can play a potential role to remove emerging contaminants when using microalgae technology for wastewater effluent treatment.


Assuntos
Chlorella vulgaris/metabolismo , Estrogênios/metabolismo , Poluentes Químicos da Água/metabolismo , Biotransformação , Estradiol/metabolismo , Estrogênios/análise , Estrona/metabolismo , Etinilestradiol/análise , Etinilestradiol/metabolismo , Microalgas/metabolismo , Fotólise , Águas Residuárias/química , Poluentes Químicos da Água/análise
2.
Chemosphere ; 261: 128199, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33113666

RESUMO

A microalgal-bacterial membrane photobioreactor (MB-MPBR) was developed for simultaneous COD and nutrients (N and P) removals from synthetic municipal wastewater in a single stage for a long-term operation over 350 days. The effects of hydraulic retention time (HRT) and N/P ratio on the biological performance were systematically evaluated for the first time. The results showed that a lower N/P ratio (3.9:1) and shorter HRT (2 d) promoted more biomass production, as compared to a high HRT (3 d) and a high N/P ratio (9.7:1). The highest biomass concentration (2.55 ± 0.14 g L-1) and productivity (127.5 mg L-1·d-1) were achieved at N/P ratio of 3.9:1 and HRT of 2 d due to the highest nitrogen and phosphorus loadings under such conditions. A COD and ammonia-N removal efficiency of over 96% and 99%, respectively, were achieved regardless of HRTs and N/P ratios. In the absence of nitrogen or phosphorus deficiency, shorter HRT (2 d) yielded a higher nitrogen and phosphorus uptake but lower removal efficiency. In addition, the imbalance N/P ratio (9.7:1) would decrease nitrogen or phosphorus removal. Overall, the results suggested that it was feasible to simultaneously achieve complete or high removal of COD, nitrogen, and phosphorous in MB-MPBR under the appropriate conditions. This study demonstrated for the first time that MB-MPBR is a promising technology that could achieve a high-quality effluent meeting the discharge standards of COD and nutrients in one single step.


Assuntos
Nitrogênio/metabolismo , Fósforo/metabolismo , Fotobiorreatores , Eliminação de Resíduos Líquidos/instrumentação , Amônia/metabolismo , Análise da Demanda Biológica de Oxigênio , Biomassa , Chlorella vulgaris/metabolismo , Microalgas/metabolismo , Nitrogênio/análise , Fotobiorreatores/microbiologia , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química
3.
NPJ Syst Biol Appl ; 6(1): 14, 2020 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-32415097

RESUMO

Cells can sense changes in their extracellular environment and subsequently adapt their biomass composition. Nutrient abundance defines the capability of the cell to produce biomass components. Under nutrient-limited conditions, resource allocation dramatically shifts to carbon-rich molecules. Here, we used dynamic biomass composition data to predict changes in growth and reaction flux distributions using the available genome-scale metabolic models of five eukaryotic organisms (three heterotrophs and two phototrophs). We identified temporal profiles of metabolic fluxes that indicate long-term trends in pathway and organelle function in response to nitrogen depletion. Surprisingly, our calculations of model sensitivity and biosynthetic cost showed that free energy of biomass metabolites is the main driver of biosynthetic cost and not molecular weight, thus explaining the high costs of arginine and histidine. We demonstrated how metabolic models can accurately predict the complexity of interwoven mechanisms in response to stress over the course of growth.


Assuntos
Eucariotos/crescimento & desenvolvimento , Eucariotos/metabolismo , Nitrogênio/metabolismo , Animais , Bacteroidetes/metabolismo , Biomassa , Células CHO/metabolismo , Carbono/metabolismo , Isótopos de Carbono , Chlorella vulgaris/metabolismo , Cricetulus , Genoma , Saccharomyces cerevisiae/metabolismo , Inanição , Yarrowia/metabolismo
4.
Aquat Toxicol ; 223: 105495, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32371336

RESUMO

Platinum-based antineoplastic drugs (PBADs) enter the environment via hospital and municipal wastes as reactive and highly toxic molecules. Chlorella vulgaris is a freshwater microalgae and is used as an excellent aquatic model for toxicity assessment. In the present study, the toxicity of PBADs to C. vulgaris was investigated for better understanding of PBADs environmental toxicity. The algae were cultured in Bold´s Basal Medium (BBM) and exposed to different concentrations of PBADs for 48, 72 and 96 h. Then, cell proliferation, the synthesis of photosynthetic pigments, protein content, malondialdehyde (MDA) release and antioxidant potential were determined. IC50 s of cisplatin, carboplatin and oxaliplatin for 96 h of exposure were 106.2, 124.3 and 153.9 mg/L respectively. Cell proliferation, synthesis of chlorophyll a, chlorophyll b and algal protein content significantly decreased in a time and dose-dependent manner. The release of MDA to culture media significantly increased and antioxidant potential decreased. Cisplatin showed more toxic effects on C. vulgaris compared to carboplatin and oxaliplatin indicating its severe toxicity for marine organisms. PBADs induce their toxic effects in algal cells via the interaction with DNA, production of free radicals (such as reactive oxygen species), lipid peroxidation and cell wall damages. Due to these toxic effects of PBADs for various environmental organisms, there must be severe restriction on their release into the environment.


Assuntos
Antineoplásicos/toxicidade , Chlorella vulgaris/efeitos dos fármacos , Microalgas/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Antioxidantes/metabolismo , Carboplatina/toxicidade , Chlorella vulgaris/metabolismo , Clorofila/metabolismo , Clorofila A/metabolismo , Cisplatino/toxicidade , Água Doce/química , Peroxidação de Lipídeos/efeitos dos fármacos , Malondialdeído/metabolismo , Microalgas/metabolismo , Oxaliplatina/toxicidade , Fotossíntese/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo
5.
Bull Environ Contam Toxicol ; 104(6): 799-803, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32388572

RESUMO

Azoxystrobin (AZ), pyraclostrobin (PYR) and coumoxystrobin (COU) exert negative impacts on Chlorella vulgaris. Thus, in this study, C. vulgaris was used to assess the respiratory toxicity of AZ, PYR and COU by determining the acute toxicity, complex III activity and ATP viability. The 96 h-EC50 values of AZ, PYR and COU for C. vulgaris were 1.85, 2.21 and 1.62 mg/L, respectively. AZ, PYR and COU exerted significant effects on complex III activity and ATP viability after exposure to 0.71, 1.01 and 1.08 mg/L of the fungicides. The binding potentials of AZ, PYR and COU toward ubiquinone were - 10.44, - 9.31 and - 12.98 kcal/mol, respectively, which had adverse effects on amino acids. These results provided new insight into the potential acute respiratory toxicity mechanisms of these strobilurin fungicides in algae.


Assuntos
Acrilatos/toxicidade , Chlorella vulgaris/efeitos dos fármacos , Cumarínicos/toxicidade , Fungicidas Industriais/toxicidade , Pirimidinas/toxicidade , Estrobilurinas/toxicidade , Poluentes Químicos da Água/toxicidade , Trifosfato de Adenosina/metabolismo , Sítios de Ligação , Chlorella vulgaris/metabolismo , Relação Dose-Resposta a Droga , Complexo III da Cadeia de Transporte de Elétrons/metabolismo , Simulação de Acoplamento Molecular , Oxirredução , Testes de Toxicidade Aguda , Ubiquinona/metabolismo
6.
Int J Radiat Biol ; 96(7): 919-928, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32159411

RESUMO

Purpose: To evaluate the effects of polyethylene glycol (PEG) 6000 pretreatment on growth and physiological responses of eukaryotic microalga Chlorella vulgaris exposed to ionizing irradiation.Materials and methods: The microalgal cells pretreated with different PEG concentrations (0, 5, 10 and 20%) and then exposed to 300 Gray gamma irradiation at a dose rate of 0.5 Gy s-1. The various growth and physiological parameters including algal growth, cell size, the degree of electrolyte leakage (EL) and lipid peroxidation, the content of pigments and proline and the activity of antioxidant enzymes under gamma-free or 300 Gray gamma irradiation conditions were examined.Results: The results showed that PEG stimulated a higher growth and cell size under both stress-free and gamma-stress conditions. The maximum growth and cell size was reported when the algae was pretreated with 10% PEG. A relative increase of catalase activity was observed in all samples after exposing to gamma irradiation. However, the highest value was recorded for the gamma-radiated algae pretreated with 10% PEG. In the absence of PEG, gamma irradiation induced a significant reduction in ascorbate peroxidase activity, but with PEG pretreatment, the enzyme activity remained constant or even increased after gamma irradiation. On the other hand, although gamma irradiation stress generally suppressed the activity of superoxide dismutase in all cells, pretreating the algae with PEG could diminish this suppressing effect at all applied concentrations. Compared to the PEG-free controls, a lower rate of chlorophylls and membrane integrity loss was shown in the PEG-treated algae when exposed to gamma stress. Total carotenoid content in PEG-treated algae was also similar under both gamma-free and gamma-radiated conditions. A PEG-independent increase in proline accumulation was reported under gamma-irradiation treatment.Conclusions: Overall, the results suggested that PEG pretreatment could improve gamma-irradiation tolerance in C. vulgaris probably by stimulating a range of enzymatic and non-enzymatic reactive oxygen species scavenging systems. The microalgae may also consume PEG to break down and use it as an alternative source of carbon during stress which should be further studied in detail.


Assuntos
Chlorella vulgaris/efeitos dos fármacos , Chlorella vulgaris/efeitos da radiação , Raios gama/efeitos adversos , Polietilenoglicóis/farmacologia , Protetores contra Radiação/farmacologia , Carotenoides/metabolismo , Chlorella vulgaris/crescimento & desenvolvimento , Chlorella vulgaris/metabolismo , Clorofila/metabolismo , Relação Dose-Resposta a Droga , Eletrólitos/metabolismo , Malondialdeído/metabolismo , Prolina/metabolismo
7.
Ecotoxicol Environ Saf ; 194: 110379, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32143104

RESUMO

Bioconcentration of 4-tert-Octylphenol (OP) in freshwater algae Chlorella vulgaris was investigated by considering the effects of algal growth and exudate excretion. The OP uptake in algae was approximately 113 mg kg-1 after 24 h, and the uptake rate constant was estimated as 2.4 × 104 L kg-1 d-1. The OP sorption onto exudates reduced OP bioavailability to C. vulgaris to 11% after 24 h, with a sorption coefficient of 9.7 × 103 L kg-1. The elimination of OP by algae growth (0.80 d-1) was dominant over real elimination (0.60 d-1). The calculated bioconcentration factor of OP in C. vulgaris following uptake and elimination rate constants was 4.0 × 104 L kg-1. Further, bioaccumulation of OP in Daphnia magna was investigated by considering both aqueous and dietary (C. vulgaris) exposures. Uptake and elimination rates of OP via water were 1.6 × 104 L kg-1 d-1 and 0.95 d-1, respectively, while ingestion rate and assimilation efficiency via diet were 0.41 d-1 and 58%, respectively. The OP accumulation in D. magna predominantly occurred via water (63%) relative to diet (37%), resulting in a bioaccumulation factor of 2.7 × 104 L kg-1. The estimated trophic transfer factor was 0.25, suggesting that OP biomagnification was unlikely in the C. vulgaris-D. magna trophic relationship.


Assuntos
Bioacumulação , Chlorella vulgaris/metabolismo , Daphnia/metabolismo , Modelos Biológicos , Fenóis/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Disponibilidade Biológica , Chlorella vulgaris/efeitos dos fármacos , Cadeia Alimentar , Fenóis/metabolismo , Toxicocinética , Poluentes Químicos da Água/metabolismo
8.
Chemosphere ; 252: 126566, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32222521

RESUMO

The effects of different concentrations of graphene oxide (GO) on intracellular metabolism in Chlorella vulgaris (C. vulgaris) and removal of nitrogen and phosphorus nutrients by C. vulgaris from synthetic wastewater were studied. The results demonstrated that cell division of Chlorella vulgaris increased at 24 h and decreased at 96 h after exposure to different concentrations of GO. The removal rates of total nitrogen (TN), ammoniacal nitrogen (NH3-N), phosphate (PO43--P), and chemical oxygen demand (COD) were 24.1%, 70.0%, 37.0%, and 39.6%, respectively, when the concentration of GO was 0.01 mg/L 10 mg/L GO induced severe plasmolysis and cytoplasmic contraction. Furthermore, the protein-like exopolysaccharide (EPS) content of algal cells exposed to 10 mg/L GO decrease to 10.8% of the control group. Simultaneously, the reactive oxygen species (ROS) level was 175.4% of control group. The biological responses to 10 mg/L GO included increase in ROS level, inhibition of saccharide metabolism, and degradation of amino acids. In addition, high concentrations of 10 mg/L GO weakened the carbon fixation process in algal cells. These stress-response behaviors increased cell permeability and oxidative stress. Overall, these findings provide new insights regarding the effects of GO on algal cellular stress responses.


Assuntos
Chlorella vulgaris/fisiologia , Grafite/química , Ciclo do Carbono , Chlorella vulgaris/metabolismo , Nitrogênio/análise , Nutrientes , Fosfatos/metabolismo , Fósforo/metabolismo , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias
9.
Ecotoxicol Environ Saf ; 194: 110392, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32171965

RESUMO

The sensitivity of individual organisms towards toxic agents is an important indicator of environmental pollution. However, organism-specific quantification of sensitivity towards pollutants remains a challenge. In this study, we determined the sensitivity of Chlorella vulgaris (C. vulgaris) and Scenedesmus quadricauda (S. quadricauda) towards three ionic liquids (ILs), 1-alkyl-3-methyl-imidazolium chlorides [Cnmim][Cl] (n = 4,6,8). We kept all external parameters constant to identify the biotic parameters responsible for discrepancies in species sensitivity, and used flow cytometry to determine four conventional endpoints to characterise cell viability and cell vitality. Our results demonstrate that after exposure to the ILs, cell proliferation was inhibited in both species. At the same time, the cell size, complexity and membrane permeability of both algae also increased. However, while Chl a synthesis by S. quadricauda was inhibited, that of C. vulgaris was enhanced. S. quadricauda has evolved a metabolic defense that can counteract the decreased esterase activity that has been shown to occur in the presence of ILs. While it is likely that S. quadricauda was less sensitive than C. vulgaris to the ILs because of this metabolic defense, this alga may also exhibit better membrane resistance towards ILs.


Assuntos
Chlorella vulgaris/efeitos dos fármacos , Líquidos Iônicos/toxicidade , Scenedesmus/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Sobrevivência Celular/efeitos dos fármacos , Chlorella vulgaris/citologia , Chlorella vulgaris/metabolismo , Citometria de Fluxo , Scenedesmus/citologia , Scenedesmus/metabolismo , Especificidade da Espécie
10.
Ecotoxicol Environ Saf ; 192: 110261, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32018153

RESUMO

The Chlorella vulgaris has been generally recognized as a promising microalgal model to study stress-related responses due to its ability to withstand against ionizing and non-ionizing radiation. The objective of the present study was to investigate the effect of CaCl2 pre-treatment at different concentrations on the responses of microalga C. vulgaris under gamma radiation toxicity. Changes in growth, physiological parameters and biochemical compositions of the algae pretreated with 0.17 (normal), 5, and 10 mM CaCl2 were analyzed under 300 Gy gamma irradiation and compared to those of gamma-free control. The results showed that parameters including specific growth rate, cell size, chlorophyll and protein contents, ascorbate peroxidase (APX), and superoxide dismutase (SOD) activity, Ferric Reducing Antioxidant Power (FRAP), and the ratios of nucleic acid to protein negatively affected by gamma irradiation. All these parameters, except for the ratios of nucleic acid to protein significantly increased in the algae when pretreated with a CaCl2 content higher than normal concentration. The analysis also showed that parameters including catalase activity, proline, and carotenoid content, the level of lipid peroxidation, and electrolyte leakage (EL) significantly increased under gamma irradiation but not affected significantly under different CaCl2 pre-treatments. Additionally, specific growth rate, chlorophyll a and protein content, APX and SOD activity, FRAP, lipid peroxidation, electrolyte leakage, and the ratios of nucleic acid to protein were the only parameters that significantly affected by the interaction of gamma toxicity and CaCl2 pretreatment. Overall, the results suggested that regardless of the CaCl2 effect, the algal cells responded to gamma radiation more efficiently by increasing proline, carotenoids content, and CAT activity. More important, it was concluded that calcium had an essential role in modifying the detrimental effect of gamma toxicity on the algae mainly by increasing the activity of ascorbate peroxidase and superoxide dismutase and maintaining the reducing antioxidant power (FRAP) of the cells at a high level.


Assuntos
Cloreto de Cálcio/farmacologia , Chlorella vulgaris/efeitos da radiação , Raios gama/efeitos adversos , Tolerância a Radiação/efeitos dos fármacos , Antioxidantes/metabolismo , Ascorbato Peroxidases/metabolismo , Carotenoides/metabolismo , Catalase/metabolismo , Chlorella vulgaris/efeitos dos fármacos , Chlorella vulgaris/crescimento & desenvolvimento , Chlorella vulgaris/metabolismo , Clorofila/metabolismo , Clorofila A/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos da radiação , Microalgas/efeitos dos fármacos , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , Microalgas/efeitos da radiação , Prolina/metabolismo , Superóxido Dismutase/metabolismo
11.
Sci Rep ; 10(1): 3011, 2020 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-32080302

RESUMO

Chlorella vulgaris, like a wide range of other microalgae, are able to grow mixotrophically. This maximizes its growth and production of polysaccharides (PS). The extracted polysaccharides have a complex monosaccharide composition (fructose, maltose, lactose and glucose), sulphate (210.65 ± 10.5 mg g-1 PS), uronic acids (171.97 ± 5.7 mg g-1 PS), total protein content (32.99 ± 2.1 mg g-1 PS), and total carbohydrate (495.44 ± 8.4 mg g-1 PS). Fourier Transform infrared spectroscopy (FT-IR) analysis of the extracted polysaccharides showed the presence of N-H, O-H, C-H, -CH3, >CH2, COO-1, S=O and the C=O functional groups. UV-Visible spectral analysis shows the presence of proteins, nucleic acids and chemical groups (ester, carbonyl, carboxyl and amine). Purified polysaccharides were light green in color and in a form of odorless powder. It was soluble in water but insoluble in other organic solvents. Thermogravimetric analysis demonstrates that Chlorella vulgaris soluble polysaccharide is thermostable until 240°C and degradation occurs in three distinct phases. Differential scanning calorimetry (DSC) analysis showed the characteristic exothermic transition of Chlorella vulgaris soluble polysaccharides with crystallization temperature peaks at 144.1°C, 162.3°C and 227.7°C. The X-ray diffractogram illustrated the semicrystalline nature of these polysaccharides. Silver nanoparticles (AgNPs) had been biosynthesized using a solution of Chlorella vulgaris soluble polysaccharides. The pale green color solution of soluble polysaccharides was turned brown when it was incubated for 24 hours with 100 mM silver nitrate in the dark, it showed peak maximum located at 430 nm. FT-IR analysis for the biosynthesized AgNPs reported the presence of carbonyl, -CH3, >CH2, C-H,-OH and -NH functional groups. Scanning and transmission electron microscopy show that AgNPs have spherical shape with an average particle size of 5.76. Energy-dispersive X-ray (EDX) analysis showed the dominance of silver. The biosynthesized silver nanoparticles were tested for its antimicrobial activity and have positive effects against Bacillus sp., Erwinia sp., Candida sp. Priming seeds of Triticum vulgare and Phaseolus vulgaris with polysaccharides solutions (3 and 5 mg mL-1) resulted in significant enhancement of seedling growth. Increased root length, leaf area, shoot length, photosynthetic pigments, protein content, carbohydrate content, fresh and dry biomass were observed, in addition these growth increments may be attributed to the increase of antioxidant activities.


Assuntos
Antibacterianos/farmacologia , Antioxidantes/farmacologia , Chlorella vulgaris/química , Reguladores de Crescimento de Planta/farmacologia , Polissacarídeos/farmacologia , Prata/farmacologia , Antibacterianos/isolamento & purificação , Antioxidantes/isolamento & purificação , Bacillus/efeitos dos fármacos , Bacillus/crescimento & desenvolvimento , Candida/efeitos dos fármacos , Candida/crescimento & desenvolvimento , Chlorella vulgaris/crescimento & desenvolvimento , Chlorella vulgaris/metabolismo , Erwinia/efeitos dos fármacos , Erwinia/crescimento & desenvolvimento , Nanopartículas Metálicas/química , Testes de Sensibilidade Microbiana , Tamanho da Partícula , Extratos Vegetais/química , Reguladores de Crescimento de Planta/isolamento & purificação , Polissacarídeos/isolamento & purificação , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Sementes/efeitos dos fármacos , Sementes/crescimento & desenvolvimento , Prata/química , Triticum/efeitos dos fármacos , Triticum/crescimento & desenvolvimento
12.
Chemosphere ; 247: 125668, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31931307

RESUMO

Mesotrione is a selective herbicide used to prevent weed attack of corn. It is extensively used, and hence, is being increasingly detected in aquatic ecosystems and may exert adverse effects on aquatic organisms. To evaluate the effects of mesotrione on photosynthesis-related gene expression, antioxidant enzyme activities, subcellular structure, and membrane integrity in algal cells, a comprehensive study was conducted using the green alga, Chlorella vulgaris. Exposure to 4-50 mg/L mesotrione resulted in a progressive inhibition of cell growth, with a 96-h median inhibition concentration (96 h- ErC50) value of 18.8 mg/L. Further, 18 and 37.5 mg/L mesotrione affected the algal photosynthetic capacity by decreasing the cell pigment content and reducing transcript abundance of photosynthesis-related genes. Mesotrione induced oxidative stress, as confirmed by increased cellular levels of reactive oxygen species (ROS) and malondialdehyde (MDA), and altered antioxidant enzyme activities. It also damaged the algal cellular structure, observed as plasmolysis, blurred organelle shape, and disruption of the chloroplast structure. Flow cytometry analysis revealed that mesotrione exposure led to uneven cell growth and interior irregularities in the algal cell. The apparent propidium iodide (PI) influx also confirmed that the herbicide induced damage of the cell membrane integrity. This study will facilitate the understanding of the physiological and morphological changes induced by mesotrione in C. vulgaris cells, and provide basic information for understanding the biological mechanisms of mesotrione-induced algal toxicity.


Assuntos
Membrana Celular/efeitos dos fármacos , Chlorella vulgaris/efeitos dos fármacos , Cicloexanonas/farmacologia , Espaço Intracelular/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Antioxidantes/metabolismo , Chlorella vulgaris/citologia , Chlorella vulgaris/metabolismo , Clorófitas/efeitos dos fármacos , Cicloexanonas/toxicidade , Herbicidas/toxicidade , Fotossíntese/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Poluentes Químicos da Água/toxicidade
13.
Bioengineered ; 11(1): 141-153, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-31994978

RESUMO

Cell immobilization on the magnetic nanoparticles (MNPs) and magnetic harvesting is a novel approach for microalgal cells separation. To date, the effect of these nanoparticles on microalgal cells was only studied over a short period of time. More studies are hence needed for a better understanding of the magnetic harvesting proposes or environmental concerns relating to long-term exposure to nanoparticles. In this study, the impact of various concentrations of MNPs on the microalgal cells growth and their metabolic status was investigated over 12 days. More than 60% reduction in mitochondrial activity and pigments (chlorophyll a, chlorophyll b, and carotenoids) content occurred during the first 6 days of exposure to ≥50 µg/mL nanoparticles. However, more than 50% growth inhibitory effect was seen at concentrations higher than 400 µg/mL. Exposure to MNPs gradually induced cellular adaptation and after about 6 days of exposure to stress generating concentrations (˂400 µg/mL) of IONs, microalgae could overcome the imposed damages. This work provides a better understanding regarding the environmental impact of MNPs and appropriate concentrations of these particles for future algal cells magnetic immobilization and harvesting.


Assuntos
Chlorella vulgaris/química , Nanopartículas/química , Células Imobilizadas/química , Células Imobilizadas/metabolismo , Chlorella vulgaris/crescimento & desenvolvimento , Chlorella vulgaris/metabolismo , Clorofila/análise , Clorofila/metabolismo , Clorofila A/análise , Clorofila A/metabolismo , Fenômenos Magnéticos , Microalgas/química , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo
14.
Chemosphere ; 247: 125936, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31978664

RESUMO

Silver nanoparticles (AgNPs) can gradually accumulate in algae to exert their toxicity; however, there is little knowledge about their bioaccumulation dynamics. For the first time, this study reports the effect of surface charge of AgNPs on their bioaccumulation dynamics in freshwater algae (Chlorella vulgaris) using biodynamic modeling. Polyethylene-coated AgNPs (PEI-AgNPs) and citrate-coated AgNPs (Cit-AgNPs) were selected as positively and negatively charged AgNPs, i.e., P-AgNPs and N-AgNPs, respectively. Their uptake and elimination dynamics were investigated at a concentration of 50% inhibition of growth rate values (EC50) and 10% inhibition of growth rate values (EC10). The one-component model can generally well simulate the algal uptake and elimination kinetics of N-AgNPs but not of P-AgNPs. At both concentrations, the uptake rate constants (ku) for P-AgNPs were ∼20 times higher than that for N-AgNPs. The parameters of biphasic elimination kinetics revealed that P-AgNPs were eliminated faster than N-AgNPs during depuration compared to in subsequent processes. Compared with N-AgNPs, extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and dark-field imaging revealed that P-AgNPs can be rapidly absorbed on the algal cell surface membrane owing to their remarkably lower energy barrier between algal cells, resulting in a faster adsorption/uptake process and aggregation of algal cells. Our results clearly demonstrate that the AgNPs exhibited surface charge-dependent bioaccumulation dynamics in algal cells. Thus, AgNP surface charge primarily influences the AgNP accumulation dynamics in algal cells.


Assuntos
Chlorella vulgaris/metabolismo , Nanopartículas Metálicas/análise , Prata/metabolismo , Adsorção , Bioacumulação , Chlorella vulgaris/efeitos dos fármacos , Ácido Cítrico/metabolismo , Água Doce
15.
Chemosphere ; 238: 124576, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31421462

RESUMO

This study assesses and compares the influence of silver nanoparticles (AgNPs) and silver nitrate (AgNO3) on the fatty acid composition, pigments, and growth indices of Chlorella vulgaris. Toxicity testing was carried at the estimated and/or above predicted environmental concentrations of AgNPs and AgNO3. AgNO3 treatments impaired the population growth of C. vulgaris about 2-183 times more than the respective AgNPs ones. The pigments displayed a concentration-dependent decrease in response to both forms of silver; however, AgNO3 displayed higher severity to the pigments than AgNPs. In exposure to 10 µg L-1 AgNO3, the contents of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid, respectively, demonstrated a reduction of about 5, 3, 4, and 4 times when compared with the same respective concentration of AgNPs. Total amounts of saturated (∑SFA), monounsaturated (∑MUFA), and polyunsaturated (∑PUFA) fatty acids as well as the ratio of unsaturated to saturated ones (Unsat./Sat.) displayed somewhat similar-concentration responses. ∑SFA exhibited a hormesis response, and ∑MUFA, ∑PUFA, and Unsat./Sat. did a decreasing trend with increasing concentration of AgNPs and AgNO3. Myristoleic acid, nervonic acid, and eicosadienoic acid revealed the highest sensitivity. Pearson analysis illustrated the highest correlation among myristoleic acid, eicosenoic acid, and nervonic acid as well as among palmitic acid, stearic acid, palmitoleic acid, and oleic acid. Taken together, AgNPs and the released ions could disrupt physiological health state of microalgae through perturbation in the fatty acid composition (especially MUFAs and PUFAs) and other macromolecules. These types of bioperturbations could change the good health state of aquatic ecosystems.


Assuntos
Chlorella vulgaris/crescimento & desenvolvimento , Poluentes Ambientais/toxicidade , Ácidos Graxos/metabolismo , Nanopartículas Metálicas/toxicidade , Nitrato de Prata/toxicidade , Prata/toxicidade , Carotenoides/metabolismo , Chlorella vulgaris/metabolismo , Clorofila/metabolismo , Clorofila A/metabolismo , Ecossistema , Ecotoxicologia , Ácidos Graxos Monoinsaturados/metabolismo , Microalgas/efeitos dos fármacos , Testes de Toxicidade
16.
Environ Sci Pollut Res Int ; 27(1): 111-117, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31037532

RESUMO

Wastewater rich in organic carbon, nitrogen and phosphorus may serve as a convenient source of carbon and nutrients for a year-long microalgae production. Scientific reports indicate that some single-cell microalgae such as Chlorella and Scenedesmus, are highly tolerant to wastewater environments and efficiently remove biogenic compounds. The aim of this study was to determine the possibility of using the effluent produced in the process of anaerobic degradation of whey as a culture medium for the multiplication of Chlorella vulgaris algae biomass and to characterise their growth efficiency and rate. The content of nitrogen and phosphorus in wastewater was sufficient for conducting an effective culture of algae. The efficiency of nitrogen removal in the flow system was 15.61 ± 1.38 mg N/dm3/day.


Assuntos
Chlorella vulgaris/fisiologia , Eliminação de Resíduos Líquidos/métodos , Biomassa , Chlorella vulgaris/metabolismo , Fermentação , Microalgas/crescimento & desenvolvimento , Nitrogênio/metabolismo , Fósforo/metabolismo , Scenedesmus/metabolismo , Águas Residuárias
17.
Mol Biol Rep ; 47(1): 369-379, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31642042

RESUMO

Human diploid fibroblasts (HDFs) cultured in vitro have limited capacity to proliferate after population doubling is repeated several times, and they enter into a state known as replicative senescence or cellular senescence. This study aimed to investigate the effect of Chlorella vulgaris on the replicative senescence of HDFs by determining the expression of senescence-associated genes. Young and senescent HDFs were divided into untreated control and C. vulgaris-treated groups. A senescence-associated gene transcription analysis was carried out with qRT-PCR. Treatment of young HDFs with C. vulgaris reduced the expression of SOD1, CAT and CCS (p < 0.05). In addition, the expression of the SOD2 gene was increased with C. vulgaris treatment in young, pre-senescent and senescent HDFs (p < 0.05). Treatment of senescent HDFs with C. vulgaris resulted in the downregulation of TP53 gene expression. The expression of the CDKN2A gene was significantly decreased upon C. vulgaris treatment in young and senescent HDFs. C. vulgaris treatment was also found to significantly upregulate the expression of the MAPK14 gene in pre-senescent HDFs. In addition, the expression of MAPK14 was significantly upregulated compared to that in the untreated senescent HDFs (p < 0.05). In summary, the expression of senescence-associated genes related to antioxidants and the insulin/insulin-like growth factor-1 signalling, DNA damage-associated signalling, cell differentiation and cell proliferation pathways was modulated by C. vulgaris during replicative senescence of human diploid fibroblasts.


Assuntos
Senescência Celular/efeitos dos fármacos , Senescência Celular/genética , Chlorella vulgaris/metabolismo , Antioxidantes/metabolismo , Catalase/genética , Catalase/metabolismo , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Senescência Celular/fisiologia , Chlorella vulgaris/patogenicidade , Dano ao DNA/efeitos dos fármacos , Diploide , Fibroblastos/metabolismo , Expressão Gênica/efeitos dos fármacos , Genes p53/genética , Humanos , Masculino , Proteína Quinase 14 Ativada por Mitógeno/genética , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Cultura Primária de Células , Transdução de Sinais/efeitos dos fármacos , Superóxido Dismutase/metabolismo , Superóxido Dismutase-1/genética , Superóxido Dismutase-1/metabolismo
18.
J Biotechnol ; 307: 35-43, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31678206

RESUMO

Microalgae synthesize a variety of potentially high-value compounds. Due to their robust cell wall, cell disruption is necessary to improve extraction of these compounds. While cell disruption methods have been optimized for lipid and protein extraction, there are limited studies for other bioactive compounds. The present study investigated the effect of freeze-drying combined with sonication or ball-milling on the extraction of antioxidant and plant biostimulating compounds from Chlorella sp., Chlorella vulgaris and Scenedesmus acutus. Both cell disruption methods resulted in higher extract yields from the biomass compared to freeze-dried biomass using 50% methanol as a solvent. Antioxidant activity of Chlorella extracts was generally higher than freeze-dried extracts based on the diphenylpicrylhydrazyl (DPPH) and ß-carotene linoleic acid assays. However, the effectiveness of each treatment varied between microalgae strains. Sonication resulted in the highest antioxidant activity in Chlorella sp. extracts. Ball-milling gave the best results for C. vulgaris extracts in the DPPH assay. Both cell disruption methods decreased antioxidant activity in S. acutus extracts. Plant biostimulating activity was tested using the mung bean rooting assay. Damaging the membrane by freeze-drying was sufficient to release the active compounds using water extracts. In contrast, both cell disruption methods negatively affected the biological activity of the extracts. These results indicate that bioactive compounds in microalgae are sensitive to post-harvest processes and their biological activity can be negatively affected by cell disruption methods. Care must be taken to not only optimize yield but to also preserve the biological activity of the target compounds.


Assuntos
Antioxidantes/isolamento & purificação , Chlorella vulgaris/metabolismo , Microalgas/metabolismo , Compostos Fitoquímicos/isolamento & purificação , Extratos Vegetais/isolamento & purificação , Scenedesmus/metabolismo , Sonicação/métodos , Antioxidantes/metabolismo , Biomassa , Chlorella vulgaris/química , Liofilização , Metanol , Microalgas/química , Compostos Fitoquímicos/metabolismo , Extratos Vegetais/química , Scenedesmus/química , Solventes
19.
J Ethnopharmacol ; 249: 112392, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31739107

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: The multidrug-resistant (MDR) pathogen, Mycobacterium tuberculosis, still remains as one of the major threat to mankind, despite the availability of a live attenuated vaccine and effective antibiotics. Marine microalgae, at all times, act as a key resource for valuable therapeutic compounds with limited side effects. AIM OF THE STUDY: The present explorative attempt is to isolate the biomolecules of pharmacological importance from the marine microalgae, Chlorella vulgaris, and to evaluate its effect on the ever dreadful disease, Tuberculosis. The study is also aimed to develop an economically feasible methodology for by-products extraction from microalgae. MATERIALS AND METHODS: Fatty acids-carotenoid complexes (FACC), namely, FACC-1 (red oil) and FACC-2 (brown oil) were isolated, in addition to lipid and lutein from the Chlorella Growth Factor (CGF, a protein fraction enriched with vitamins, minerals and carbohydrates)-extracted spent biomass through column chromatography. RESULTS: FACC-1 is a complex of fatty acids such as oleic and linoleic acids, and carotenoids such as canthaxanthin and neoxanthin. FACC-2 is a complex of oleic, linoleic and linolenic acids and carotenoids (cryptoxanthin and echinenone). Initial screening for evaluation of minimum bactericidal concentration (MBC) of FACC-1 and -2 was performed against Mycobacterium tuberculosis strains such as H37Rv, SHRE sensitive clinical isolate and SHRE resistant clinical isolate. MBC was noted at 10 µg/mL by FACC-1 and at 5 µg/mL by FACC-2, determined using colony forming and Lucipherase Reporter Mycobacteriophages (LRP) assay. Testing in the PAN sensitive isolates indicated that the MBC was noted at 5 µg/mL by FACC-1 and at 2.5 µg/mL by FACC-2. Complete inhibition (100%) was observed at 100 µg/mL by FACC-1 and at 50 µg/mL by FACC-2. Testing of FACC-1 and FACC-2 individually as well as in combination on two different types of MDR strains confirmed the efficacy of the algal oils, wherein in MDR-strain 1, FACC-1 revealed 50% inhibition at 10 µg/mL, while FACC-2 exhibited the same at 5 µg/mL. Conversely, in the case of MDR strain-2, MBC of FACC-1 was at 500 µg/mL and MBCof FACC-2 to be at 250 µg/mL. No significant synergistic effect was observed on combining both the oils. CONCLUSION: The study signifies the development of a potent therapeutic agent comprising of a complex of anti-TB agent (fatty acids) and antioxidants (carotenoids) from the CGF-extracted spent biomass of C. vulgaris.


Assuntos
Antituberculosos/farmacologia , Carotenoides/farmacologia , Chlorella vulgaris/metabolismo , Ácidos Graxos/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Antituberculosos/administração & dosagem , Antituberculosos/isolamento & purificação , Biomassa , Carotenoides/administração & dosagem , Carotenoides/isolamento & purificação , Relação Dose-Resposta a Droga , Ácidos Graxos/administração & dosagem , Ácidos Graxos/isolamento & purificação , Testes de Sensibilidade Microbiana
20.
J Biosci Bioeng ; 129(1): 93-98, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31331795

RESUMO

The present study investigated the effect of light intensity and mixing on microalgae growth in a raceway by comparing the performance of a paddlewheel to a combination of paddlewheel and CO2 spargers in a 20 L raceway. The increase of light intensity was known to be able to increase the microalgal growth rate. Increasing paddlewheel rotation speed from 13 to 30 rpm enhanced C. vulgaris growth by enhancing culture mixing. Simulation results using computational fluid dynamics (CFD) indicated that both the turnaround areas of the raceway and the area opposite the paddlewheel experienced very low flow velocities (dead zones) of less than 0.1 m/min, which could cause cell settling and slow down growth. The simulated CFD velocity distribution in the raceway was validated by actual velocity measurements. The installation of CO2 spargers in the dead zones greatly increased flow velocity. The increase of paddlewheel rotation speed reduced the dead zones and hence increased algal biomass production. By complementing the raceway paddlewheel with spargers providing CO2 at 30 mL/min, we achieved a dry cell weight of 5.2 ± 0.2 g/L, which was about 2.6 times that obtained without CO2 sparging.


Assuntos
Dióxido de Carbono/metabolismo , Chlorella vulgaris/metabolismo , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , Biomassa , Reatores Biológicos , Dióxido de Carbono/química , Chlorella vulgaris/química , Chlorella vulgaris/crescimento & desenvolvimento , Chlorella vulgaris/efeitos da radiação , Hidrodinâmica , Luz , Microalgas/química , Microalgas/efeitos da radiação
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