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1.
Nat Commun ; 12(1): 570, 2021 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-33495440

RESUMO

Melting of the Greenland Ice Sheet is a leading cause of land-ice mass loss and cryosphere-attributed sea level rise. Blooms of pigmented glacier ice algae lower ice albedo and accelerate surface melting in the ice sheet's southwest sector. Although glacier ice algae cause up to 13% of the surface melting in this region, the controls on bloom development remain poorly understood. Here we show a direct link between mineral phosphorus in surface ice and glacier ice algae biomass through the quantification of solid and fluid phase phosphorus reservoirs in surface habitats across the southwest ablation zone of the ice sheet. We demonstrate that nutrients from mineral dust likely drive glacier ice algal growth, and thereby identify mineral dust as a secondary control on ice sheet melting.


Assuntos
Eutrofização/fisiologia , Camada de Gelo , Microalgas/crescimento & desenvolvimento , Minerais/metabolismo , Fósforo/metabolismo , Biomassa , Ecossistema , Congelamento , Geografia , Aquecimento Global , Groenlândia , Gelo , Microalgas/citologia , Microalgas/ultraestrutura , Microscopia Eletrônica de Varredura , Estações do Ano
2.
Chemosphere ; 262: 128422, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182085

RESUMO

This study evaluated the toxicity of Cr(VI) to microalgae Chlorella vulgaris, and its removal by continuous microalgae cultivation in membrane photobioreactor (MPBR). Batch cultivation in photobioreactors showed that low concentration of Cr(VI) (0.5 and 1.0 mg L-1) stimulated the growth of C. vulgaris, while 2.0 and 5.0 mg L-1 Cr(VI) in the wastewater significantly inhibited the growth of C. vulgaris. Superoxide dismutase and catalase activities that represented cellular antioxidant capacity significantly increased at 0.5 and 1.0 mg L-1 Cr(VI), and then gradually decreased with the continuous increase of Cr(VI) concentration. The content of malondialdehyde, which represents the degree of cellular oxidative damage, increased with the increase of Cr(VI) concentration and reached the peak value at 2.0 mg L-1 Cr(VI). C. vulgaris was then cultured in MPBR equipped with hollow-fiber ultrafiltration membrane module to achieve continuous removal of Cr from wastewater. With the in-situ solid-liquid separation function of the membrane module, solid retention time (SRT) and hydraulic retention time (HRT) of the reactor could be controlled separately. Experimental results showed that both SRT and HRT had significant effects on the algal biomass production and pollutants removal. During the continuous operation, MPBR achieved a maximum total Cr reduction of 50.0% at HRT of 3-day and SRT of 40-day, and a maximum volumetric removal rate of total Cr of 0.21 mg L-1 d-1 at HRT of 2-day and SRT of 40-day.


Assuntos
Chlorella vulgaris/fisiologia , Cromo/toxicidade , Fotobiorreatores , Eliminação de Resíduos Líquidos , Biomassa , Chlorella vulgaris/crescimento & desenvolvimento , Cromo/análise , Estudos Longitudinais , Membranas Artificiais , Microalgas/crescimento & desenvolvimento , Oxirredução , Águas Residuárias
3.
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
4.
Ecotoxicol Environ Saf ; 203: 111000, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32736119

RESUMO

Microplastics are identified as a great threat to marine environments. However, knowledge of their impacts on phytoplankton, especially for the diatoms is scarce. Herein, the effects of different polyvinyl chloride (PVC) microplastic concentrations and contact times (24, 48, 72 and 96 h) on the Fv/Fm and cell density of Phaeodactylum tricornutum (B255), Chaetoceros gracilis (B13) and Thalassiosira sp. (B280) were investigated to evaluate the toxic effects of microplastics on marine diatoms. The effects of PVC microplastics on the morphology of the diatoms was observed by SEM. The order of sensitivity to 1 µm PVC microplastics among three marine diatoms was B13 > B280 > B255, showing that the toxic effects varied with different microalgae species. Furthermore, the presence of a siliceous cell wall played a minimal role in protecting cells from the physical attack of PVC microplastics, with no significant difference from the common cell wall. PVC microplastics caused dose-dependent adverse effects on three marine diatoms. High PVC concentrations (200 mg/L) reduced the chlorophyll content, inhibited Fv/Fm, and affected the photosynthesis of three marine diatoms. The PVC microplastics adsorbed and caused physical damage on the structure of algal cells. Interactions between PVC microplastics and diatoms may be the probable reason for the negative effects of PVC on diatoms.


Assuntos
Diatomáceas/efeitos dos fármacos , Microplásticos/toxicidade , Cloreto de Polivinila/toxicidade , Poluentes Químicos da Água/toxicidade , Adsorção , Clorofila/metabolismo , Diatomáceas/crescimento & desenvolvimento , Diatomáceas/fisiologia , Relação Dose-Resposta a Droga , Microalgas/efeitos dos fármacos , Microalgas/crescimento & desenvolvimento , Microalgas/fisiologia , Fotossíntese/efeitos dos fármacos , Fitoplâncton/efeitos dos fármacos , Fitoplâncton/crescimento & desenvolvimento , Fitoplâncton/fisiologia , Fatores de Tempo
5.
Aquat Toxicol ; 226: 105551, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32707232

RESUMO

Strains of microalgae vary in traits between species and populations due to adaptation or stochastic processes. Traits of individual strains may also vary depending on the acclimatization state and external forces, such as abiotic stress. In this study we tested how metal tolerance differs among marine diatoms at three organizational levels: species, populations, and strains. At the species level we compared two pelagic Baltic Sea diatoms (Skeletonema marinoi and Thalassiosira baltica). We found that the between-species differences in tolerance (EC50) to the biologically active metals (Cu, Co, Ni, and Zn) was similar to that within-species. In contrast, the two species differed significantly in tolerance towards the non-essential metals, Ag (three-fold higher in T. baltica), Pb and Cd (two and three-fold higher in S. marinoi). At the population level, we found evidence that increased tolerance against Cu and Co (17 and 41 % higher EC50 on average, respectively) had evolved in a S. marinoi population subjected to historical mining activity. On a strain level we demonstrate how the growth phase of cultures (i.e., cellular densities above exponential growth) modulated dose-response relationships to Ag, Cd, Co, Cu, and Zn. Specifically, the EC50's were reduced by 10-60 % in non-exponentially growing S. marinoi (strain RO5AC), depending on metal. For the essential metals these differences were often larger than the average differences between the two species and populations. Consequently, without careful experimental design, interactions between nutrient limitation and metal stress may interfere with detection of small, but evolutionary and ecologically important, differences in tolerance between microalgae. To avoid such artifacts, we outline a semi-continuous cultivation approach that maintains, and empirically tests, that exponential growth is achieved. We argue that such an approach is essential to enable comparison of population or strain differences in tolerance using dose-response tests on cultures of microalgae.


Assuntos
Aclimatação/efeitos dos fármacos , Diatomáceas/crescimento & desenvolvimento , Metais Pesados/toxicidade , Microalgas/crescimento & desenvolvimento , Poluentes Químicos da Água/toxicidade , Diatomáceas/efeitos dos fármacos , Microalgas/efeitos dos fármacos , Mineração , Dinâmica Populacional , Especificidade da Espécie
6.
Ecotoxicol Environ Saf ; 203: 110966, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32678755

RESUMO

We studied the effect of the chemical interaction of nutrients and the ethylenediamine tetraacetic acid (EDTA) on metals toxicity. Growth inhibition tests of Pseudokirchneriella subcapitata by nutrient metals copper (Cu) and zinc (Zn), and the non-nutrient metal lead (Pb), were performed. The high-enriched Bold's Basal medium (BBm) and two low-enriched standard media, recommended by the Organization for Economic Cooperation and Development (OECDm) and Environmental Protection Agency-algal assay procedure medium (AAPm), were used in this study. The metals toxicity was affected by the interaction of nutrients and EDTA. Cu+2 was more toxic in the OECDm (EC50 20.3 µg/L), while Pb+2 (EC50 23.1 µg/L) and Zn+2 (EC50 99.4 µg/L) in the AAPm. Non-toxic effect of these metals was observed in BBm, but the exclusion of EDTA shifted it into a toxic medium. Finally, we found that the toxicity of the studied nutrient metals is mainly influenced by EDTA, which reduced the concentration of ionized metals, while the toxicity of the non-nutrient metal is affected by EDTA and phosphates.


Assuntos
Monitoramento Biológico/métodos , Quelantes/farmacologia , Ácido Edético/farmacologia , Metais Pesados/toxicidade , Microalgas/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Bioensaio , Cobre/toxicidade , Relação Dose-Resposta a Droga , Interações Medicamentosas , Chumbo/toxicidade , Microalgas/crescimento & desenvolvimento , Modelos Teóricos , Zinco/toxicidade
7.
Mar Environ Res ; 158: 105005, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32501269

RESUMO

In order to investigate the combined toxicities of copper nanoparticles (nano-Cu) with microplastic on microalgae Skeletonema costatum, growth inhibition tests were carried out. The toxic effects of copper nanoparticles and microplastic on the microalgae under singleness and coexistence conditions were investigated. Both copper nanoparticles and microplastic inhibited the growth of S. costatum. The growth inhibition ratio (IR) increased with the increasing of particle concentrations and incubation time. The toxicity of copper nanoparticles was reduced with the addition of microplastic. The concentrations of Cu2+ in the medium with or without addition of microplastic were determined. It was found that adsorption of Cu2+ on microplastic and aggregation between copper nanoparticles and microplastic are the main reasons for attenuation of toxicity of nano-Cu with adding microplastic. The adhesion and aggregate interactions between microalgae and nanomaterial were also approved by the observations through scanning electron microscopy.


Assuntos
Cobre , Diatomáceas , Microalgas , Nanopartículas , Cobre/toxicidade , Microalgas/efeitos dos fármacos , Microalgas/crescimento & desenvolvimento , Microplásticos , Nanopartículas/toxicidade , Plásticos
8.
PLoS One ; 15(6): e0234710, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32555718

RESUMO

Heterotrophic cultures are the most effective approach to overcome low growth rate challenge in the most commercial microalgae. However, the mechanism through which heterotrophic condition regulates algae metabolism are not completely clear. Alternative Splicing (AS) is a common posttranscriptional process by which transcriptome and proteome plasticity increases at different environmental conditions. To identify and characterize of AS events in Auxenochlorella protothecoides microalga grown in autotrophic and heterotrophic, RNA-Seq data were analysed. We found that AS increased with the transition from autotrophic to heterotrophic condition. 705 and 660 differentially expressed (DEG) and spliced (DAS) genes were identified for A.protothecoides was transferred from autotrophic to heterotrophic condition, respectively. Moreover, there was slight coverage between DEG and DAS genes. Furthermore, functional analysis showed that the DAS genes are most frequently related to ion binding and stimulus response. The results also indicated that prevalence of Intron retention is associated with down-regulation of the genes involved in carotenoid biosynthesis. This study provides valuable insights into transcriptional and posttranscriptional plasticity of microalgae during growth mode change.


Assuntos
Processamento Alternativo , Perfilação da Expressão Gênica , Processos Heterotróficos/genética , Microalgas/genética , Microalgas/metabolismo , Carotenoides/metabolismo , Genômica , Microalgas/crescimento & desenvolvimento , Fatores de Tempo
9.
Sci Rep ; 10(1): 7612, 2020 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-32376837

RESUMO

Herbicide contamination of nearshore tropical marine ecosystems is widespread and persistent; however, risks posed by most 'alternative' herbicides to tropical marine microalgae remain poorly understood. Experimental exposures of the important but understudied microalgae Rhodomonas salina to seven individual Photosystem II (PSII) inhibitor herbicides (diuron, metribuzin, hexazinone, tebuthiuron, bromacil, simazine, propazine) led to inhibition of effective quantum yield (ΔF/Fm') and subsequent reductions in specific growth rates (SGR). The concentrations which reduced ΔF/Fm' by 50% (EC50) ranged from 1.71-59.2 µg L-1, while the EC50s for SGR were 4-times higher, ranging from 6.27-188 µg L-1. Inhibition of ΔF/Fm' indicated reduced photosynthetic capacity, and this correlated linearly with reduced SGR (R2 = 0.89), supporting the application of ∆F/Fm' inhibition as a robust and sensitive indicator of sub-lethal toxicity of PSII inhibitors for this microalga. The three non-PSII inhibitor herbicides (imazapic, haloxyfop and 2,4-Dichlorophenoxyacetic acid (2,4-D)) caused low or no toxic responses to the function of the PSII or growth at the highest concentrations tested suggesting these herbicides pose little risk to R. salina. This study highlights the suitability of including R. salina in future species sensitivity distributions (SSDs) to support water quality guideline development for the management of herbicide contamination in tropical marine ecosystems.


Assuntos
Herbicidas/toxicidade , Microalgas/efeitos dos fármacos , Clima Tropical , Poluentes Químicos da Água/toxicidade , Ecotoxicologia , Microalgas/enzimologia , Microalgas/crescimento & desenvolvimento , Complexo de Proteína do Fotossistema II/antagonistas & inibidores
10.
Sci Rep ; 10(1): 7688, 2020 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-32376848

RESUMO

Online monitoring of algal biotechnological processes still requires development to support economic sustainability. In this work, fluorescence spectroscopy coupled with chemometric modelling is studied to monitor simultaneously several compounds of interest, such as chlorophyll and fatty acids, but also the biomass as a whole (cell concentration). Fluorescence excitation-emission matrices (EEM) were acquired in experiments where different environmental growing parameters were tested, namely light regime, temperature and nitrogen (replete or deplete medium). The prediction models developed have a high R2 for the validation data set for all five parameters monitored, specifically cell concentration (0.66), chlorophyll (0.78), and fatty acid as total (0.78), saturated (0.81) and unsaturated (0.74). Regression coefficient maps of the models show the importance of the pigment region for all outputs studied, and the protein-like fluorescence region for the cell concentration. These results demonstrate for the first time the potential of fluorescence spectroscopy for in vivo and real-time monitoring of these key performance parameters during Nannochloropsis oceanica cultivation.


Assuntos
Biomassa , Clorofila/metabolismo , Ácidos Graxos/metabolismo , Espectrometria de Fluorescência , Estramenópilas/metabolismo , Microbiologia Industrial , Microalgas/crescimento & desenvolvimento , Estramenópilas/crescimento & desenvolvimento
11.
Biofouling ; 36(2): 138-145, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32223324

RESUMO

New processing routes and materials for non-biocidal, antifouling (AF) coatings with an improved performance are currently much sought after for a range of marine applications. Here, the processing, physical properties and marine AF performance of a fluorinated coating based on a thermoplastic (non-crosslinked) fluorinated polymer are reported. It was found that the addition of lubricating oil and hydrodynamic drag reducing microstructures improved the AF properties substantially, i.e. the settlement of a marine biofilm, containing mixed microalgae including diatoms, was reduced to low levels. More importantly, the remaining fouling was removed from the coatings at low hydrodynamic shear rates and promising AF properties were obtained. Moreover, additional potential benefits were revealed originating from the thermoplastic nature of the coating material which might result in significant cost reductions.


Assuntos
Organismos Aquáticos/crescimento & desenvolvimento , Biofilmes/crescimento & desenvolvimento , Incrustação Biológica/prevenção & controle , Polímeros de Fluorcarboneto/química , Borracha/química , Diatomáceas/crescimento & desenvolvimento , Hidrodinâmica , Microalgas/crescimento & desenvolvimento , Propriedades de Superfície
12.
Ecotoxicol Environ Saf ; 195: 110488, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32200143

RESUMO

Effect of water accommodated fractions (WAF) of #180 fuel oil on fixed carbon and nitrogen in microalgae was studied by stable isotopes. Platymonas helgolandica, Heterosigma akashiwo and Nitzschia closterium were exposed to five WAF concentrations for 96 h. The δ13C value of microalgae was significantly lower than that of the control group, indicated that carbon was limited in the WAF concentrations. The δ13C value of microalgae appeared peak valley at 48 h in control group, corresponding to the enhanced capacity in carbon fixation during microalgae photosynthesis. The physiological acclimation capacity of microalgae was revealed by the occurrence time when the δ13C value was in peak valley, and thus the physiological acclimation capacity of microalgae decreased in the order of Nitzschia closterium > Heterosigma akashiwo > Platymonas helgolandica. Principal component analysis (PCA) were applied to the δ13C value in order to verify the "hormesis" phenomenon in microalgae. The δ13C value could discriminate between stimulatory effects at low doses and inhibitory effects at high doses. In addition, the present study also investigated the effect of the nitrogen on microalgae growth. Because microalgae could still absorb the NO3-N and release of NO2-N and NH4-N in present study, the nitrogen cycle in microalgae was in the equilibrium status. The δ15N value in microalgae exhibited no obvious change with the increasing of WAF concentrations at the same time. However, due to the enrichment of nitrogen, the δ15N value first increased gradually with the time and finally was stable. Overall, the fractionation of carbon and nitrogen stable isotopes illustrated that the effect of carbon on the growth of microalgae was more prominent than nitrogen. Stable isotopes was used to investigate the influence of WAF on fixed carbon and nitrogen in microalgae growth, providing a fundamental theoretical guidance for risk assessment of marine ecological environment.


Assuntos
Carbono/análise , Óleos Combustíveis/toxicidade , Microalgas/efeitos dos fármacos , Nitrogênio/análise , Poluentes Químicos da Água/toxicidade , Ciclo do Carbono/efeitos dos fármacos , Isótopos de Carbono/análise , Clorófitas/química , Clorófitas/efeitos dos fármacos , Clorófitas/crescimento & desenvolvimento , Diatomáceas/química , Diatomáceas/efeitos dos fármacos , Diatomáceas/crescimento & desenvolvimento , Microalgas/química , Microalgas/crescimento & desenvolvimento , Isótopos de Nitrogênio/análise , Fotossíntese/efeitos dos fármacos , Estramenópilas/química , Estramenópilas/efeitos dos fármacos , Estramenópilas/crescimento & desenvolvimento , Água/química , Poluentes Químicos da Água/química
13.
PLoS One ; 15(3): e0229556, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32196504

RESUMO

The heterotrophic microalgae Crypthecodinium cohnii was usually cultivated in complex medium containing glucose, yeast extract and sea salt. For the preparation of DHA with highest purity, a new defined medium without the yeast extract was developed. Different inoculated densities, C/N ratios, temperatures, culture volumes and glucose additions were investigated to optimize the algal growth rate and DHA production. The growth period in C. cohnii was shortened from 12-14 days to 7-8 days, the OD600 was enhanced from 2.0 to 3.0, the glucose consumption was accelerated and used up on day 3-4, and the DHA content in culture were increased from 10 to 45 nmoles/300 µl batch. It was found that C. cohnii had optimal growth and DHA accumulation in 25 °C, 0.2 inoculated density, 5-10 C/N ratio, 5:1 air/culture volume ratio. This is the first time DHA production using C.cohnii has been optimized in synthetic medium. This allows preparation of uniformly radiolabeled 13C- and 14C-DHA.


Assuntos
Meios de Cultura/química , Dinoflagelados/crescimento & desenvolvimento , Ácidos Docosa-Hexaenoicos/biossíntese , Biomassa , Dinoflagelados/metabolismo , Fermentação/fisiologia , Microalgas/crescimento & desenvolvimento
14.
World J Microbiol Biotechnol ; 36(3): 42, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32130551

RESUMO

Photobioreactors (PBRs) are equipment of central importance for the massive cultivation of microalgae, providing controlled conditions for high cell productivity. There are a few popular PBR designs, with contrasting advantages and limitations, such as poor light distribution, mass transfer, or hydrodynamic behavior. Due to the environmental concerns in recent decades and the discovery of new, useful microalgal metabolites, the interest in finding alternatives to solve technological bottlenecks of PBRs has intensified. In this process, new geometries, materials, and modes of light supply were developed, generating a significant scientific and technological output, reported in papers and patents. We present a technological landscape analysis of photobioreactor design, focusing on improvements of the classical geometries and trends in industrial photobioreactors. The analysis of 412 patent documents showed a surge in innovation filing since 2005 and a reduction in the number of new documents along the last decade. The recent efforts in design improvement, the leading countries, institutes and companies that innovate, and the trends in PBR technology are presented and discussed.


Assuntos
Desenho de Equipamento/métodos , Microalgas/crescimento & desenvolvimento , Fotobiorreatores/microbiologia , Biomassa , Hidrodinâmica , Patentes como Assunto
15.
Electron. j. biotechnol ; 44: 47-57, Mar. 2020. tab, ilus, graf
Artigo em Inglês | LILACS | ID: biblio-1087699

RESUMO

BACKGROUND: The determination of kinetic parameters and the development of mathematical models are of great interest to predict the growth of microalgae, the consumption of substrate and the design of photobioreactors focused on CO2 capture. However, most of the models in the literature have been developed for CO2 concentrations below 10%. RESULTS: A nonaxenic microalgal consortium was isolated from landfill leachate in order to study its kinetic behavior using a dynamic model. The model considered the CO2 mass transfer from the gas phase to the liquid phase and the effect of light intensity, assimilated nitrogen concentration, ammonium concentration and nitrate concentration. The proposed mathematical model was adjusted with 13 kinetic parameters and validated with a good fit obtained between experimental and simulated data. CONCLUSIONS: Good results were obtained, demonstrating the robustness of the proposed model. The assumption in the model of DIC inhibition in the ammonium and nitrate uptakes was correct, so this aspect should be considered when evaluating the kinetics with microalgae with high inlet CO2 concentrations.


Assuntos
Dióxido de Carbono/análise , Microalgas/efeitos da radiação , Microalgas/fisiologia , Cinética , Vertedores , Fótons , Microalgas/isolamento & purificação , Microalgas/crescimento & desenvolvimento , Fotobiorreatores , Águas Residuárias , Modelos Biológicos , Nitratos , Nitrogênio
16.
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
17.
Chemosphere ; 248: 126094, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32041073

RESUMO

Microalgae have been considered as promising alternative for CO2 fixation and wastewater purification. In our previous work, a hybrid microalgae CO2 fixation concept has been put forward, which initially used carbonate solution absorb CO2, and then provided obtained bicarbonate as nutrition for microalgae growth to avoid the challenge of low CO2 solubility and carbon fixation efficiency in the conventional process. In this work, the proposed hybrid system was further intensified via integrating soybean wastewater nutrition removal with bicarbonate-carbon (NH4HCO3 and KHCO3) conversion. The investigation results indicated that the maximum biomass productivity (0.74 g L-1) and carbon bioconversion efficiency (46.9%) were achieved in low-NH4HCO3 concentration system with pH adjusted to 7. pH adjustment of different bicarbonate systems also enhanced total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) removal efficiency up to 87.5%, 99.5% and 77.6%, respectively. In addition, maximum neutral lipid (14.4 mg L-1·d-1) and polysaccharide (14.5 mg L-1·d-1) productivities could be obtained in the KHCO3 systems, while higher crude protein productivity (48.1 mg L-1·d-1) was yielded in the NH4HCO3 systems.


Assuntos
Bicarbonatos/química , Ciclo do Carbono , Microalgas/metabolismo , Compostos de Potássio/química , Soja/metabolismo , Águas Residuárias/química , Purificação da Água/métodos , Análise da Demanda Biológica de Oxigênio , Biomassa , Carbono/metabolismo , Dióxido de Carbono/metabolismo , Concentração de Íons de Hidrogênio , Microalgas/crescimento & desenvolvimento , Nitrogênio/metabolismo , Fósforo/metabolismo , Reciclagem
18.
Sci Rep ; 10(1): 1530, 2020 01 30.
Artigo em Inglês | MEDLINE | ID: mdl-32001724

RESUMO

Microalgae cultivation on tannery wastewater (TWW) has been examined in some studies as a possible biological application to reduce contamination load and discharge effluents safely. However, Growth aspects, different tolerate strains and enriching the medium were not well investigated. In our study we applied Scenedesmus sp., Chlorella variabilis and Chlorella sorokiniana with different TWW concentrations. C. sorokiniana and C. variabilis cell density, chlorophyll, and sugar content grew substantially as compared to control. C. sorokiniana biomass and total lipids folded three and two times in 25% and 40% TWW, respectively as compared to control. Scenedesmus sp. showed longer lag phase and lower performance compared to the other two strains. Kelp waste extract (KWE) was added to balance the nutrients supply for C. sorokiniana, of which growth and effluents indicators were then greatly promoted in all concentrations. As the lag phase was shortened from 8 to 4 days in 60% concentration, subsequently, chlorophyll, carbohydrates, biomass and total lipids appreciated by 184%, 400%, 162% and 135%, respectively. Furthermore, the COD and ammonium removals improved by 51% and 45%, respectively. These outcomes emphasize the suitability of using TWW for microalgae cultivation with the suitable concentration while adding kelp waste extract for further enhancement.


Assuntos
Biocombustíveis/microbiologia , Águas Residuárias/microbiologia , Biomassa , Chlorella/crescimento & desenvolvimento , Lipídeos/biossíntese , Microalgas/crescimento & desenvolvimento , Scenedesmus/crescimento & desenvolvimento , Águas Residuárias/análise
19.
World J Microbiol Biotechnol ; 36(3): 39, 2020 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-32095995

RESUMO

Landfilling of municipal waste, an environmental challenge worldwide, results in the continuous formation of significant amounts of leachate, which poses a severe contamination threat to ground and surface water resources. Landfill leachate (LL) is generated by rainwater percolating through disposed waste materials and must be treated effectively before safe discharge into the environment. LL contains numerous pollutants and toxic substances, such as dissolved organic matter, inorganic chemicals, heavy metals, and anthropogenic organic compounds. Currently, LL treatment is carried out by a combination of physical, chemical, and microbial technologies. Microalgae are now viewed as a promising sustainable addition to the repertoire of technologies for treating LL. Photosynthetic algae have been shown to grow in LL under laboratory conditions, while some species have also been employed in larger-scale LL treatments. Treating leachate with algae can contribute to sustainable waste management at existing landfills by remediating low-quality water for recycling and reuse and generating large amounts of algal biomass for cost-effective manufacturing of biofuels and bioproducts. In this review, we will examine LL composition, traditional leachate treatment technologies, LL toxicity to algae, and the potential of employing algae at LL treatment facilities. Emphasis is placed on how algae can be integrated with existing technologies for biological treatment of LL, turning leachate from an environmental liability to an asset that can produce value-added biofuels and bioproducts for the bioeconomy.


Assuntos
Microalgas/crescimento & desenvolvimento , Poluentes Químicos da Água/análise , Biodegradação Ambiental , Biomassa , Gerenciamento de Resíduos
20.
J Biotechnol ; 312: 44-55, 2020 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-32097674

RESUMO

Artificial neural network (ANN) models can be trained to simulate the dynamic behavior of biological systems. In the present study, an ANN model was developed upon multilayer perceptron neural network architecture with 23-20-1 configuration to predict the cell concentration of microalga Chlorella vulgaris at a given time. Irradiance level, photoperiod, temperature, air flow rate, CO2 percentage of the air stream, initial cell concentration, cultivation time and the nutrient concentrations of the media were considered as the input variables of the model. Resilient backpropagation learning algorithm was used to train the model by means of 484 experimental data belonging to four studies. Bias and accuracy factors of the developed model fall into the range of 0.95-1.11 indicating the model has an excellent prediction ability. Parity plot showed a good agreement between the predicted and experimental values with R2 = 0.98. Relative importance of the inputs was evaluated using Garson's algorithm. The results of the study indicated that CO2 supply had the highest impact on the growth of C. vulgaris within the selected range of input parameters. Among macronutrients and micronutrients, highest influence was demonstrated by nitrogen and copper respectively.


Assuntos
Chlorella vulgaris/crescimento & desenvolvimento , Microalgas/crescimento & desenvolvimento , Micronutrientes/metabolismo , Modelos Biológicos , Redes Neurais de Computação , Algoritmos , Dióxido de Carbono , Técnicas de Cultura de Células , Bases de Dados Factuais , Nitrogênio , Temperatura
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