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1.
Ecotoxicol Environ Saf ; 208: 111418, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33045435

RESUMO

The present study investigates the role of Chlorella sp. in the mitigation of arsenic (iAs) induced toxicity in Oryza sativa L. The study shows, co-culture of rice seedlings with Chlorella sp. reduced the iAs accumulation, simultaneously improving the growth of seedlings under iAs treatments. While treatment with As(III) and As(V) (60 µM) alone, inflicted toxicity in rice seedlings, manifested as significant enhancement in stress markers levels (TBRAS and H2O2), this coincided with the shifting of cellular reduced state to oxidized state (reduced GSH/GSSG ratio). Contrarily, co-culturing rice seedlings with Chlorella sp. under iAs toxicity, reduced these stress markers and recovered the GSH/GSSG ratio. The GSH dependent antioxidant enzymes i.e. GR and GPX activities also exhibited significant enhancement upon co-culturing rice seedlings with Chlorella sp. against iAs stress. Simultaneously, the expression of four thiol dependent GRX genes, i.e. GRX13950, GRX35340, GRX12190 and GRX07950 were enhanced against As(III) and As(V) (60 µM), which reduced upon co-culturing with Chlorella sp. A similar trend was also observed with the expression of GST genes, where the co-culture with Chlorella sp. significantly reduced the genes expression of two isoforms (GST 38600 and GST 38610). On the contrary, the expression of S-adenosylmethionine dependent methyltransferases (SAMT) gene in rice seedlings was enhanced upon co-culturing with the Chlorella sp. against iAs stress. Overall, the results demonstrate that the rice seedlings when co-culture with Chlorella sp. ameliorates iAs toxicity through GSH dependent detoxification pathway, evident from the enhanced expression of GRX, GST, SAMT genes and activity of GSH dependent antioxidant enzymes (GR and GPX) in the rice seedlings.


Assuntos
Arsênico/toxicidade , Glutationa/metabolismo , Oryza/fisiologia , S-Adenosilmetionina/metabolismo , Poluentes do Solo/toxicidade , Antioxidantes/metabolismo , Arsênico/metabolismo , Chlorella/metabolismo , Peróxido de Hidrogênio/metabolismo , Metiltransferases/metabolismo , Oryza/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Plântula/metabolismo , Poluentes do Solo/metabolismo
2.
Ecotoxicol Environ Saf ; 207: 111301, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32949933

RESUMO

Cadmium is one of the most common heavy metals in contaminated aquatic environments and one of the most toxic contaminants for phytoplankton. Nevertheless, there are not enough studies focused on the effect of this metal in algae. Through a proteomic approach, this work shows how Cd can alter the growth, cell morphology and metabolism of the microalga Chlorella sorokiniana. Using the sequential window acquisition of all theoretical fragment ion spectra mass spectrometry (SWATH-MS), we concluded that exposure of Chlorella sorokiniana to 250 µM Cd2+ for 40 h caused downregulation of different metabolic pathways, such as photosynthesis, oxidative phosphorylation, glycolysis, TCA cycle and ribosomal proteins biosynthesis. However, photorespiration, antioxidant enzymes, gluconeogenesis, starch catabolism, and biosynthesis of glutamate, cysteine, glycine and serine were upregulated, under the same conditions. Finally, exposure to Cd also led to changes in the metabolism of carotenoids and lipids. In addition, the high tolerance of Chlorella sorokiniana to Cd points to this microalga as a potential microorganism to be used in bioremediation processes.


Assuntos
Cádmio/toxicidade , Chlorella/efeitos dos fármacos , Microalgas/efeitos dos fármacos , Proteoma/metabolismo , Poluentes Químicos da Água/toxicidade , Antioxidantes/metabolismo , Metabolismo dos Carboidratos/efeitos dos fármacos , Carotenoides/metabolismo , Chlorella/metabolismo , Espectrometria de Massas , Metais Pesados/metabolismo , Microalgas/metabolismo , Fotossíntese/efeitos dos fármacos , Proteômica
3.
Food Chem ; 337: 127777, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32799163

RESUMO

Biodegradable films based on chitosan, glycerol, and defatted Chlorella biomass (DCB) were prepared and characterized in terms of thermal stability, mechanical, water barrier, and optical properties. Increasing DCB content from 5 to 25 wt% increased tensile strength of chitosan films by 235%. The incorporation of DCB decreased both moisture content and swelling degree of chitosan/defatted Chlorella biomass (Cs/DCB) films. Furthermore, increasing the content of defatted algal biomass decreased light transmission and reduced water vapor permeability of composite films by more than 60%. As confirmed by scanning electron microscopy and Fourier transform infrared analysis, such improvement in functional and physical properties is mainly due to the homogeneous and uniform distribution of DCB into the polymeric matrix along with the establishment of strong hydrogen bond interactions between chitosan and algal biomass constituents. Moreover, Cs/DCB composite films showed more than 50% of degradation in 60 days soil burial test.


Assuntos
Quitosana/química , Chlorella/química , Biomassa , Chlorella/metabolismo , Glicerol/química , Ligação de Hidrogênio , Permeabilidade , Polímeros/química , Espectroscopia de Infravermelho com Transformada de Fourier , Água/química
4.
Ecotoxicol Environ Saf ; 207: 111546, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33254405

RESUMO

Degradation solutions containing atrazine need to be further purified before they are discharged into the aquatic environment. With the objectives of evaluating removal capacity of the microalga Chlorella sp. toward atrazine in degradation solutions and toxicity of the degradation products, we investigated the removal efficiency (RE) and bioaccumulation of atrazine in the microalgae after an 8 d exposure to diluted degraded solutions containing 40 µg/L and 80 µg/L of atrazine as well as degradation products in the present study. Moreover, pure atrazine solutions with similar concentrations were simultaneously inoculated with the microalgae in order to distinguish the influence of the products. The photocatalytic degradation results showed that 31.4% of atrazine was degraded after 60 min, and three degradation products, desisopropyl-atrazine (DIA), desethyl-atrazine (DEA), and desethyl-desisopropyl-atrazine (DEIA) were detected. After an 8-d exposure, 83.0% and 64.3% of atrazine were removed from the degraded solutions containing 40 µg/L and 80 µg/L of atrazine, respectively. In comparison with the control, i.e., pure atrazine solution with equal concentration, Chlorella sp. in the degraded atrazine solution showed lower RE and growth rate. The photosynthetic parameters, especially performance index (PIABS), clearly displayed the differences between treatments. The values of PIABS of Chlorella sp. cultured in degradation atrazine for 8 days were significantly lower (P < 0.01) than that in the corresponding pure atrazine, suggesting potential inhibitory effect of degradation products on the microalgae. Atrazine and the degradation products inhibited algal photosynthesis via depressed light absorption and electron transport, and reduced utilization of light energy via energy dissipation. Our results demonstrated that microalgae Chlorella sp. had an encouraging atrazine removal potential and the degradation products of atrazine may inhibit algal growth and removal capability. This study may be useful for the application of microalgae in herbicide wastewater treatment and understanding algal removal of atrazine in natural aquatic environment.


Assuntos
Atrazina/metabolismo , Microalgas/metabolismo , Poluentes Químicos da Água/metabolismo , Atrazina/toxicidade , Chlorella/metabolismo , Herbicidas/metabolismo , Herbicidas/toxicidade , Microalgas/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Soluções , Poluentes Químicos da Água/toxicidade
5.
Nat Commun ; 11(1): 5985, 2020 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-33239636

RESUMO

The spontaneous self-assembly of multicellular ensembles into living materials with synergistic structure and function remains a considerable challenge in biotechnology and synthetic biology. Here, we exploit the aqueous two-phase separation of dextran-in-PEG emulsion micro-droplets for the capture, spatial organization and immobilization of algal cells or algal/bacterial cell communities to produce discrete multicellular spheroids capable of both aerobic (oxygen producing) and hypoxic (hydrogen producing) photosynthesis in daylight under air. We show that localized oxygen depletion results in hydrogen production from the core of the algal microscale reactor, and demonstrate that enhanced levels of hydrogen evolution can be achieved synergistically by spontaneously enclosing the photosynthetic cells within a shell of bacterial cells undergoing aerobic respiration. Our results highlight a promising droplet-based environmentally benign approach to dispersible photosynthetic microbial micro-reactors comprising segregated cellular micro-niches with dual functionality, and provide a step towards photobiological hydrogen production under aerobic conditions.


Assuntos
Reatores Biológicos/microbiologia , Hidrogênio/metabolismo , Microbiologia Industrial/métodos , Microbiota/fisiologia , Oxigênio/metabolismo , Aerobiose/fisiologia , Hipóxia Celular/fisiologia , Chlorella/metabolismo , Escherichia coli/metabolismo , Fotossíntese/fisiologia , Energia Renovável
6.
J Vis Exp ; (162)2020 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-32865530

RESUMO

In the United States, 35% of the total carbon dioxide (CO2) emissions come from the electrical power industry, of which 30% represent natural gas electricity generation. Microalgae can biofix CO2 10 to 15 times faster than plants and convert algal biomass to products of interest, such as biofuels. Thus, this study presents a protocol that demonstrates the potential synergies of microalgae cultivation with a natural gas power plant situated in the southwestern United States in a hot semi-arid climate. State-of-the-art technologies are used to enhance carbon capture and utilization via the green algal species Chlorella sorokiniana, which can be further processed into biofuel. We describe a protocol involving a semi-automated open raceway pond and discuss the results of its performance when it was tested at the Tucson Electric Power plant, in Tucson, Arizona. Flue gas was used as the main carbon source to control pH, and Chlorella sorokiniana was cultivated. An optimized medium was used to grow the algae. The amount of CO2 added to the system as a function of time was closely monitored. Additionally, other physicochemical factors affecting algal growth rate, biomass productivity, and carbon fixation were monitored, including optical density, dissolved oxygen (DO), electroconductivity (EC), and air and pond temperatures. The results indicate that a microalgae yield of up to 0.385 g/L ash-free dry weight is attainable, with a lipid content of 24%. Leveraging synergistic opportunities between CO2 emitters and algal farmers can provide the resources required to increase carbon capture while supporting the sustainable production of algal biofuels and bioproducts.


Assuntos
Ciclo do Carbono , Dióxido de Carbono/metabolismo , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , Tanques , Centrais Elétricas , Biocombustíveis , Biomassa , Chlorella/química , Chlorella/crescimento & desenvolvimento , Chlorella/metabolismo , Lipídeos/análise , Microalgas/química , Oxigênio/metabolismo
7.
Nat Biomed Eng ; 4(12): 1168-1179, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32948855

RESUMO

The control of viral outbreaks requires nucleic acid diagnostic tests that are sensitive, simple and fast. Here, we report a highly sensitive and specific one-pot assay for the fluorescence-based detection of RNA from pathogens. The assay, which can be performed within 30-50 min of incubation time and can reach a limit of detection of 0.1-attomolar RNA concentration, relies on a sustained isothermal reaction cascade producing an RNA aptamer that binds to a fluorogenic dye. The RNA aptamer is transcribed by the T7 RNA polymerase from the ligation product of a promoter DNA probe and a reporter DNA probe that hybridize with the target single-stranded RNA sequence via the SplintR ligase (a Chlorella virus DNA ligase). In 40 nasopharyngeal SARS-CoV-2 samples, the assay reached positive and negative predictive values of 95 and 100%, respectively. We also show that the assay can rapidly detect a range of viral and bacterial RNAs.


Assuntos
/diagnóstico , Técnicas de Diagnóstico Molecular/métodos , RNA Viral/genética , Transcrição Genética/genética , /virologia , Chlorella/metabolismo , DNA/genética , DNA Ligases/metabolismo , RNA Polimerases Dirigidas por DNA/metabolismo , Testes Diagnósticos de Rotina/métodos , Fluorescência , Humanos , Técnicas de Amplificação de Ácido Nucleico , Pandemias/prevenção & controle , Sensibilidade e Especificidade , Proteínas Virais/metabolismo
8.
Sci Rep ; 10(1): 14119, 2020 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-32839563

RESUMO

In the present work, the effect of α-Fe2O3-nanoparticles (IONPs) supplementation at varying doses (0, 10, 20 and, 30 mg L-1) at the intermittent stage (after 12th day of growth period) was studied on the growth and biogas production potential of Chlorella pyrenoidosa. Significant enhancements in microalgae growth were observed with all the tested IONPs doses, the highest (2.94 ± 0.01 g L-1) being at 20 mg L-1. Consequently, the composition of the biomass was also improved. Based on the precedent determinations, theoretical chemical oxygen demand (CODth) as well as theoretical and stoichiometric methane potential (TMP, and SMP) were also estimated. The CODth, TMP, SMP values indicated IONPs efficacy for improving biogas productivity. Further, the biochemical methane potential (BMP) test was done for IONPs supplemented biomass. The BMP test revealed up to a 25.14% rise in biogas yield (605 mL g-1 VSfed) with 22.4% enhanced methane content for 30 mg L-1 IONPs supplemented biomass over control. Overall, at 30 mg L-1 IONPs supplementation, the cumulative enhancements in biomass, biogas, and methane content proffered a net rise of 98.63% in biomethane potential (≈ 2.86 × 104 m3 ha-1 year-1) compared to control. These findings reveal the potential of IONPs in improving microalgal biogas production.


Assuntos
Biocombustíveis/análise , Chlorella/crescimento & desenvolvimento , Chlorella/metabolismo , /administração & dosagem , Análise da Demanda Biológica de Oxigênio , Biomassa , Metano/biossíntese , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo
9.
Chemosphere ; 260: 127553, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32653748

RESUMO

The impact of ionizing radiation on microorganisms such as microalgae is a topic of increasing importance for understanding the dynamics of aquatic ecosystems in response to environmental radiation, and for the development of efficient approaches for bioremediation of mining and nuclear power plants wastewaters. Currently, nothing is known about the effects of ionizing radiation on the microalgal cell wall, which represents the first line of defence against chemical and physical environmental stresses. Using various microscopy, spectroscopy and biochemical techniques we show that the unicellular alga Chlorella sorokiniana elicits a fast response to ionizing radiation. Within one day after irradiation with doses of 1-5 Gy, the fibrilar layer of the cell wall became thicker, the fraction of uronic acids was higher, and the capacity to remove the main reactive product of water radiolysis increased. In addition, the isolated cell wall fraction showed significant binding capacity for Cu2+, Mn2+, and Cr3+. The irradiation further increased the binding capacity for Cu2+, which appears to be mainly bound to glucosamine moieties within a chitosan-like polymer in the outer rigid layer of the wall. These results imply that the cell wall represents a dynamic structure that is involved in the protective response of microalgae to ionizing radiation. It appears that microalgae may exhibit a significant control of metal mobility in aquatic ecosystems via biosorption by the cell wall matrix.


Assuntos
Chlorella/metabolismo , Metais/metabolismo , Antioxidantes/metabolismo , Biodegradação Ambiental , Biomassa , Parede Celular/metabolismo , Chlorella/efeitos dos fármacos , Ecossistema , Microalgas/metabolismo , Radiação Ionizante , Águas Residuárias
10.
Sci Rep ; 10(1): 10647, 2020 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-32606320

RESUMO

Algae-bacteria interaction is one of the main factors underlying the formation of harmful algal blooms (HABs). The aim of this study was to develop a genome-wide high-throughput screening method to identify HAB-influenced specific interactive bacterial metabolites using a comprehensive collection of gene-disrupted E. coli K-12 mutants (Keio collection). The screening revealed that a total of 80 gene knockout mutants in E. coli K-12 resulted in an approximately 1.5-fold increase in algal growth relative to that in wild-type E. coli. Five bacterial genes (lpxL, lpxM, kdsC, kdsD, gmhB) involved in the lipopolysaccharide (LPS) (or lipooligosaccharide, LOS) biosynthesis were identified from the screen. Relatively lower levels of LPS were detected in these bacteria compared to that in the wild-type. Moreover, the concentration-dependent decrease in microalgal growth after synthetic LPS supplementation indicated that LPS inhibits algal growth. LPS supplementation increased the 2,7-dichlorodihydrofluorescein diacetate fluorescence, as well as the levels of lipid peroxidation-mediated malondialdehyde formation, in a concentration-dependent manner, indicating that oxidative stress can result from LPS supplementation. Furthermore, supplementation with LPS also remarkably reduced the growth of diverse bloom-forming dinoflagellates and green algae. Our findings indicate that the Keio collection-based high-throughput in vitro screening is an effective approach for the identification of interactive bacterial metabolites and related genes.


Assuntos
Genoma Bacteriano , Proliferação Nociva de Algas , Lipopolissacarídeos/biossíntese , Chlorella/efeitos dos fármacos , Chlorella/metabolismo , Dinoflagelados/efeitos dos fármacos , Dinoflagelados/metabolismo , Escherichia coli/genética , Peroxidação de Lipídeos , Lipopolissacarídeos/genética , Lipopolissacarídeos/farmacologia , Malondialdeído/metabolismo
11.
Sci Rep ; 10(1): 11917, 2020 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-32681007

RESUMO

[223Ra]RaCl2 is the first alpha-particle emitting radiopharmaceutical to be used for castration-resistant prostate cancer patients with bone metastases because of its excellent therapeutic effects. [223Ra]RaCl2 is excreted via the intestine into feces, and some is absorbed from the intestine into the blood, which may be undesirable in terms of the exposure to radiation. Recently, we showed that a complex of myo-inositol-hexakisphosphate (InsP6) with zinc is a useful decorporation agent against radiostrontium. In this study, we hypothesized that Zn-InsP6 could bind to not only strontium but also to radium, and could inhibit the absorption of radium from the intestine. In in vitro binding experiments, Zn-InsP6 showed a high binding affinity for radium. In in vivo biodistribution experiments by intravenous injection of [223Ra]RaCl2 after treatment of Zn-InsP6, mice treated with Zn-InsP6 showed significantly lower bone accumulation of radioactivity (34.82 ± 1.83%Dose/g) than the mice in the non-treatment control group (40.30 ± 2.78%Dose/g) at 48 h postinjection. These results indicate that Zn-InsP6 bound radium in the intestine and inhibited the absorption of radium into the blood. Therefore, the insoluble Zn-InsP6 complex has high potential to decrease the side effects of [223Ra]RaCl2.


Assuntos
Absorção de Radiação , Neoplasias Ósseas/tratamento farmacológico , Neoplasias Ósseas/secundário , Intestinos/efeitos da radiação , Rádio (Elemento)/administração & dosagem , Rádio (Elemento)/uso terapêutico , Administração Oral , Animais , Cátions , Chlorella/metabolismo , Concentração de Íons de Hidrogênio , Masculino , Camundongos , Ácido Fítico/química , Ácido Fítico/metabolismo , Radioatividade , Radioisótopos/administração & dosagem , Radioisótopos/uso terapêutico , Distribuição Tecidual , Zinco/farmacologia
12.
J Biosci Bioeng ; 130(3): 295-305, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32507481

RESUMO

The yield and quality of lipids extracted from microalgal biomass are critical factors in the production of microalgae-based biodiesel. The green microalga Chlorella homosphaera, isolated from Beira Lake, Colombo, Sri Lanka was employed in the present study to identify the effect of chlorophyll removal and cell disruption methods on lipid extraction yield, fatty acid methyl ester (FAME) profile and quality parameters of biodiesel; including cetane number (CN), iodine value (IV), degree of unsaturation (DU) and high heating value (HHV). In the first section of this study, chlorophyll was removed from dry microalgae biomass prior to lipid extraction. Through the analysis of FAME profiles, it was observed that chlorophyll removal yielded biodiesel of enhanced quality, albeit with a lipid loss of 44.2% relative to the control. In the second section of the study, mechanical cell disruption strategies including grinding, autoclaving, water bath heating and microwaving were employed to identify the most effective method to improve lipid recovery from chlorophyll-removed microalgae biomass. Autoclaving (121 °C, 20 min sterilization time, total time 2 h) was the most effective cell disruption technique of the methods tested, in terms of lipid extraction yield (39.80%) and also biodiesel quality. Moreover, it was observed that employing cell disruption subsequent to chlorophyll removal has a significant impact on the FAME profile of microalgae-based biodiesel, and consequently served to increase HHV and CN although IV and DU did not vary significantly.


Assuntos
Biocombustíveis/microbiologia , Biotecnologia , Chlorella/metabolismo , Microalgas/metabolismo , Biomassa , Chlorella/microbiologia , Ácidos Graxos/metabolismo , Microalgas/microbiologia
13.
Aquat Toxicol ; 224: 105498, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32402915

RESUMO

The current study focuses on the ecotoxicity of cobalt oxide nanoparticles (Co3O4 NPs) in the aquatic environment towards freshwater microalgae, Chlorella minutissima. The interaction of Co3O4 NPs with microalgae shows the growth suppressing effect. The 72 h EC 50 (effective concentration of a chemical having 50% of its impact) values of Co3O4 NPs for C. minutissima was 38.16 ± 1.99 mg/L. The decline in chlorophyll a content and increase in reactive oxygen species (ROS) also indicated the compromised physiological state of microalgae. An increased LDH (lactate dehydrogenase) level in treated samples suggests membrane disintegration by Co3O4 NPs. Light microscopy, scanning electron microscopy (SEM) and Energy Dispersive X-Ray-Scanning electron microscopy (EDX-SEM) further confirm cell entrapment and deposition of Co3O4 NPs on the cell surface. Cellular internalization of NPs, as shown by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), also contributes towards the toxicity of NPs. The findings suggest the role of extracellular as well as intracellular nanoparticles (NPs) in exerting a toxic effect on the C. minutissima.


Assuntos
Chlorella/efeitos dos fármacos , Cobalto/toxicidade , Água Doce/química , Nanopartículas Metálicas/toxicidade , Microalgas/efeitos dos fármacos , Óxidos/toxicidade , Poluentes Químicos da Água/toxicidade , Chlorella/metabolismo , Clorofila A/metabolismo , Cobalto/metabolismo , Microalgas/metabolismo , Microscopia Eletrônica de Varredura , Óxidos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Poluentes Químicos da Água/metabolismo
14.
Ecotoxicol Environ Saf ; 197: 110573, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32278825

RESUMO

Antibiotics had been paid more and more attention to their toxicity to non-target aquatic organisms in the aquatic environment. As azithromycin (AZI) was an important antibiotic pollutant in water, its toxicity to aquatic organisms had been investigated. In this study, the potential aquatic ecological risk of AZI was identified by assessing the toxicity on the feeding behavior and physiological function of Daphnia magna (D. magna) under the different exposure pathways (aqueous phase exposure vs. food phase exposure). For the food Chlorella pyrenoidosa (C. pyrenoidosa), AZI could inhibit the growth and nutrition accumulation with concentration- and time-response relationship. For D. magna, the feeding behavior was inhibited by AZI under the aqueous phase exposure pathway. However, the feeding behavior was inhibited firstly and then reversed into promotion in the low and medium concentration groups and was continually promoted in the high concentration group under the food phase exposure pathway. The accumulation of polysaccharides and total protein were decreased in D. magna n the high concentration group under the aqueous phase exposure pathway, while the accumulation of polysaccharides and crude fat were decreased in the high concentration group under the food phase exposure pathway. The activity of amylase (AMS) and trypsin in D. magna were decreased after exposure to AZI under the aqueous phase exposure pathway. On the other hand, the activity of AMS in the medium and high concentration groups was decreased under the food phase exposure pathway, but the activity of trypsin was decreased in the medium concentration group and increased in the high concentration group. The levels of ROS in D. magna were also measured and increased in both exposure pathways except in the low concentration group under the food phase exposure pathway, indicating the oxidative stress injury of D. magna. Our results showed that AZI could affect the digestive enzyme activities and oxidative stress-antioxidative system, ultimately leading to the change of D. magna's feeding behavior and nutrition accumulation. These results also provided a comprehensive perspective to evaluate the toxic effects of non-lethal dose antibiotics to non-target aquatic organisms via different exposure pathways.


Assuntos
Azitromicina/toxicidade , Daphnia/efeitos dos fármacos , Comportamento Alimentar/efeitos dos fármacos , Nutrientes/metabolismo , Poluentes Químicos da Água/toxicidade , Animais , Azitromicina/metabolismo , Chlorella/metabolismo , Daphnia/metabolismo , Daphnia/fisiologia , Exposição Dietética/efeitos adversos , Exposição Ambiental/efeitos adversos , Estresse Oxidativo/efeitos dos fármacos , Poluentes Químicos da Água/metabolismo
15.
J Enzyme Inhib Med Chem ; 35(1): 913-920, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32223467

RESUMO

There is significant interest in increasing the microalgal efficiency for producing high-quality products that are commonly used as food additives in nutraceuticals. Some natural substances that can be extracted from algae include lipids, carbohydrates, proteins, carotenoids, long-chain polyunsaturated fatty acids, and vitamins. Generally, microalgal photoautotrophic growth can be maximised by optimising CO2 biofixation, and by adding sodium bicarbonate and specific bacteria to the microalgal culture. Recently, to enhance CO2 biofixation, a thermostable carbonic anhydrase (SspCA) encoded by the genome of the bacterium Sulfurihydrogenibium yellowstonense has been heterologously expressed and immobilised on the surfaces of bacteria. Carbonic anhydrases (CAs, EC 4.2.1.1) are ubiquitous metalloenzymes, which catalyse the physiologically reversible reaction of carbon dioxide hydration to bicarbonate and protons: CO2 + H2O ⇄ HCO3- + H+. Herein, we demonstrate for the first time that the fragments of bacterial membranes containing immobilised SspCA (M-SspCA) on their surfaces can be doped into the microalgal culture of the green unicellular alga, Chlorella sorokiniana, to significantly enhance the biomass, photosynthetic activity, carotenoids production, and CA activity by this alga. These results are of biotechnological interest because C. sorokiniana is widely used in many different areas, including photosynthesis research, human pharmaceutical production, aquaculture-based food production, and wastewater treatment.


Assuntos
Bactérias/enzimologia , Anidrases Carbônicas/metabolismo , Chlorella/metabolismo , Bactérias/citologia , Bactérias/crescimento & desenvolvimento , Estabilidade Enzimática , Enzimas Imobilizadas/metabolismo , Humanos
16.
Chemosphere ; 252: 126465, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32199165

RESUMO

The role of dissolved organic matter (DOM) on the biochemical behavior and toxicity of heavy metals in water is very important but complex and unclear. The present work extracted DOM from a natural water and separated it into three fractions, namely humic acid (HA), fulvic acid (FA) and transphilic acid (TPA). Optical detection showed that HA had most aromatic ring skeletons, FA had more aromatic ring hydrophilic groups, and TPA had the largest number of hydroxyl or carboxyl groups. Their effects on the toxicity of Cu by Chlorella pyrenoidosa depended on types and concentration of DOM. In the case of algal exposure to 0.003 mM initial Cu concentration, the final algal optical density increased from 0.317 of the control group to 0.345, 0.645 and 0.435 in the presence of 20, 10 mg L-1 HA, and 10 mg L-1 TPA, respectively, but were suppressed to 0.246, 0.117 and 0.234 in the presence of 10, 20 mg L-1 FA and 20 mg L-1 TPA. Most adsorption isotherms lost the linearity in the presence of HA, FA and TPA. The adsorbed Cu increased from 0.242 to 0.477 mmol g-1, following the order of increased concentration of HA, FA, and TPA. The formation of ternary complex and the multi-layer adsorption were proposed to explain the significant enhancement adsorption of Cu in the presence of FA and TPA. This study showed that the type and the density of effective functional groups in DOM determined its effects on Cu toxicity and bioavailability to algae.


Assuntos
Chlorella/metabolismo , Cobre/metabolismo , Poluentes Químicos da Água/metabolismo , Adsorção , Benzopiranos , Disponibilidade Biológica , Substâncias Húmicas , Metais Pesados
17.
Ecotoxicol Environ Saf ; 195: 110484, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32200150

RESUMO

Microplastics and nonylphenol (NP) are considered as emerging pollutant and have attracted wide attention, while their combined toxicity on aquatic organisms is barely researched. Therefore, the combined toxicity influence of NP with three types of microplastics containing polyethylene (PE1000, 13 µm and PE, 150 µm), polyamide (PA1000, 13 µm and PA, 150 µm) polystyrene (PS, 150 µm) on microalgae Chlorella pyrenoidosa was analyzed. Both growth inhibition, chlorophyll fluorescence, superoxide dismutase (SOD), malondialdehyde (MDA), and catalase (CAT) were determined. We found that single microplastics and NP both inhibited algal growth, thereby causing oxidative stress. The order of inhibition effect in single microplastics experiment was PE1000 > PA1000 > PE ≈ PS > PA. The combined toxicity experiment results indicated that the presence of microplastics had positive effect in terms of alleviating NP toxicity to C. pyrenoidosa, and the microplastics adsorption capacity to NP was the dominant contributing factor for this effect. According to the independent action model, the combined toxicity was antagonistic. Because the negative effect of smaller size microplastics on algal growth was aggravated with prolonged exposure time, the optimum effect of microplastics alleviated NP toxicity was PA1000 at 48 h, while this effect was substituted by PA at 96 h during combined toxicity. Thus, the toxicity of smaller size microplastics has a nonnegligible influence on combined toxicity. This study confirms that microplastics significantly affected the toxicity of organic pollutants on microalgae. Further research on the combined toxicity of smaller size microplastics with pollutants in chronic toxicity is needed.


Assuntos
Chlorella/efeitos dos fármacos , Microplásticos/toxicidade , Fenóis/toxicidade , Poluentes Químicos da Água/toxicidade , Adsorção , Catalase/metabolismo , Chlorella/enzimologia , Chlorella/metabolismo , Interações Medicamentosas , Malondialdeído/metabolismo , Microalgas/efeitos dos fármacos , Microalgas/enzimologia , Microalgas/metabolismo , Microplásticos/química , Estresse Oxidativo , Poliestirenos/toxicidade , Superóxido Dismutase/metabolismo , Poluentes Químicos da Água/química
18.
Chemosphere ; 248: 126101, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32045977

RESUMO

Calcium decline and cyanobacterial blooms pose a serious threat to the crustacean zooplankton Daphnia, which has a high demand for calcium. In the present study, we exposed two different clones of Daphnia pulex to different combinations of calcium concentrations (0.1, 0.5, 1.0, 5.0, 10.0 mg L-1) and food types (100% Chlorella; 80% Chlorella and 20% non-toxic Microcystis; 80% Chlorella and 20% toxic Microcystis) for 16 days, recorded the key life-history traits, and then used an exponential rise function to fit the traits. Results showed toxic Microcystis and low calcium together negatively affected the survival, development, and reproduction of Daphnia. The negative effect of non-toxic Microcystis and low calcium only affected the development and reproduction. The survival time and reproductive performance increased exponentially with increasing calcium concentration and then approached an asymptotic maximum. Both non-toxic and toxic Microcystis reduced the asymptotic maximum of the reproductive performance. The rising rate at which they reached the asymptotes differed significantly among the three food types; i.e., the reproductive performance of Daphnia was affected in a wider range of calcium concentrations under bad food quality. The findings indicated that Microcystis impaired the tolerance of Daphnia to low calcium, which may cause serious consequences in freshwater ecosystems.


Assuntos
Adaptação Fisiológica/efeitos dos fármacos , Cálcio/metabolismo , Daphnia/efeitos dos fármacos , Traços de História de Vida , Toxinas Marinhas/toxicidade , Microcystis/metabolismo , Zooplâncton/efeitos dos fármacos , Animais , Cálcio/farmacologia , Chlorella/metabolismo , Relação Dose-Resposta a Droga , Ecossistema , Água Doce/química , Toxinas Marinhas/metabolismo , Microcystis/crescimento & desenvolvimento , Reprodução/efeitos dos fármacos
19.
Environ Geochem Health ; 42(9): 2881-2894, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32026273

RESUMO

The transcriptomic response of green microalga Chlorella sorokiniana exposure to environmentally relevant concentration of cadmium(II) (Cd) and 4-n-nonylphenol (4-n-NP) was compared in the present study. Cd and 4-n-NP exposure showed a similar pattern of dys-regulated pathways. The photosystem was affected due to suppression of chlorophyll biosynthesis via down-regulation of Mg-protoporphyrin IX chelatase subunit ChlD (CHLD) and divinyl chlorophyllide a 8-vinyl-reductase (DVR) in Cd group and via down-regulation of DVR in 4-n-NP group. Furthermore, the reactive oxygen species (ROS) could be induced through down-regulation of solanesyl diphosphate synthase 1 (SPS1) and homogentisate phytyltransferase (HPT) in Cd group and via down-regulation of HPT in 4-n-NP group. Additionally, Cd and 4-n-NP would both cause the dys-regulation of carbohydrate metabolism and protein synthesis. On the other hand, there are some different responses or detoxification mechanism of C. sorokiniana to 4-n-NP stress compared to Cd exposure. The increased ROS would cause the DNA damage and protein destruction in Cd exposure group. Simultaneously, the RNA transcription was dys-regulated and a series of changes in gene expressions were observed. This included lipid metabolism, protein modification, and DNA repair, which involved in response of C. sorokiniana to Cd stress or detoxification of Cd. For 4-n-NP exposure, no effect on lipid metabolism and DNA repair was observed. The nucleotide metabolism including pyrimidine metabolism and purine metabolism was significantly up-regulated in the 4-n-NP exposure group, but not in the Cd exposure group. In addition, 4-n-NP would induce the ubiquitin-mediated proteolysis and proteasomal degradation to diminish the misfolded protein caused by ROS and down-regulation of heat shocking protein 40. In sum, the Cd and 4-n-NP could cause the same toxicological effects via the common pathways and possess similar detoxification mechanism. They also showed different responses in nucleotide metabolism, lipid metabolism, and DNA repair.


Assuntos
Cádmio/toxicidade , Chlorella/efeitos dos fármacos , Chlorella/genética , Microalgas/efeitos dos fármacos , Fenóis/toxicidade , Metabolismo dos Carboidratos/efeitos dos fármacos , Metabolismo dos Carboidratos/genética , Chlorella/metabolismo , Ecotoxicologia , Regulação da Expressão Gênica/efeitos dos fármacos , Inativação Metabólica/efeitos dos fármacos , Metabolismo dos Lipídeos/efeitos dos fármacos , Metabolismo dos Lipídeos/genética , Microalgas/genética , Microalgas/metabolismo , Fotossíntese/efeitos dos fármacos , Fotossíntese/genética , Espécies Reativas de Oxigênio/metabolismo , Transcriptoma , Poluentes Químicos da Água/toxicidade
20.
J Agric Food Chem ; 68(7): 1966-1973, 2020 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-31986037

RESUMO

Pesticide pollution of surface water represents a considerable risk for algae and thus affects the structure and stability of aquatic ecosystems. To investigate the risk of flufiprole to phytoplankton, the digestion and uptake of flufiprole as well as the toxic effects of flufiprole enantiomers and the six metabolites to Chlorella pyrenoidosa were investigated. Flufiprole enantiomers were mainly metabolized to flufiprole amide and detrifluoromethylsulfinyl flufiprole in culture medium, while various metabolites were formed in algae, notably the amide derivative and fipronil. Chlorella pyrenoidosa showed a strong absorption capacity for the flufiprole series. The EC50 values (96 h) indicated that fipronil was the most toxic compound, approximately 5 times as toxic as rac-flufiprole. R-flufiprole was more toxic than S-flufiprole. The contents of chlorophylls, malondialdehyde (MDA), reactive oxygen species (ROS), and total antioxidant capacity (T-AOC) were significantly altered by the chemicals in most cases, especially fipronil. Our results supported the potential detrimental effect of the metabolites of flufiprole on algae.


Assuntos
Chlorella/metabolismo , Inseticidas/metabolismo , Inseticidas/toxicidade , Pirazóis/metabolismo , Pirazóis/toxicidade , Biodegradação Ambiental , Biotransformação , Chlorella/efeitos dos fármacos , Clorofila/metabolismo , Inseticidas/química , Cinética , Malondialdeído/metabolismo , Pirazóis/química , Espécies Reativas de Oxigênio/metabolismo , Estereoisomerismo , Poluentes Químicos da Água/química , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/toxicidade
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