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1.
J Sci Food Agric ; 100(3): 1344-1349, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31605384

RESUMO

BACKGROUND: Water-soluble proteins extracted from the heterotrophically cultivated microalga Chlorella protothecoides have been shown to have a good solubility over a broad pH range, which makes them a promising candidate for beverage formulations. This study investigated the sensory properties of dispersions of a protein-rich extract from C. protothecoides at neutral and pH 3. RESULTS: Sensory acceptance tests of the pure extract revealed an overall low acceptance at pH 7 without sucrose addition. Sensory acceptance was significantly (P ≤ 0.05) increased by lowering the pH to 3 with citric acid, and the addition of 50 g kg-1 sucrose. Here, overall positive sensory acceptance ratings were achieved up to a protein extract concentration of 40 g kg-1 . Basic taste evaluations showed only low bitterness scores and no significant (P > 0.05) increase in bitterness with decreasing pH. CONCLUSION: It is suggested that protein-rich extracts from C. protothecoides have promising sensory properties in beverage formulations. © 2019 The Authors. Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Assuntos
Chlorella/química , Extratos Vegetais/química , Proteínas de Plantas/química , Bebidas/análise , Chlorella/crescimento & desenvolvimento , Processos Heterotróficos , Humanos , Concentração de Íons de Hidrogênio , Microalgas/química , Microalgas/crescimento & desenvolvimento , Extratos Vegetais/isolamento & purificação , Proteínas de Plantas/isolamento & purificação , Solubilidade , Paladar
2.
Chemosphere ; 239: 124672, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31494319

RESUMO

Environmental factors such as temperature and light are the most determinants in the photosynthetic productivity in microalgae. However, under extreme of these conditions, certain resistant microalgae strains possess additional abilities such as growth in the presence of high concentrations of metals and some can improve in combinations of more than one abiotic stress. Therefore, the aim of this research was to evaluate the efficiency in photosynthetic production through the oxygen balance to variations in photon intensity, and under temperature changes in a Cd-resistant strain (DcRCd100) compared to the wild-type strain (Dc1Mwt) of Dictyosphaerium chlorelloides. The results showed that the DcRCd100 strain has the maximum efficiency at 200  µmol m-2 s-1 on photosynthesis net (Pn) (96.32 ±â€¯3.63% nmol O2 ml-1 min-1) as the threshold light saturation, and an adaptation to maintain this maximum photosynthetic gross (Pg) rate at 30 °C (94.99 ±â€¯10.03% nmol O2 ml-1 min-1) due to possible modifications in the photosynthetic apparatus that is reflected in the net evolution rate of O2 to deal with such evaluated conditions. While, Dc1Mwt strain its maximum photosynthetic efficiency was at 300 µmol m-2 s-1 and 21 °C (97.72 ±â€¯2.99 and 99.85 ±â€¯0.30%nmol O2 ml-1 min-1, respectively) and in optimal response to the oxygen balance that is normally achieved by this mesophilic genus. These results provide a new prediction of mechanisms in the oxygen evolution in photosynthesis that rules the correlation between resistance and adaptation to extreme abiotic conditions in metal resistant strains of eukaryotic microalgae.


Assuntos
Cádmio/toxicidade , Chlorella/efeitos dos fármacos , Microalgas/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Adaptação Fisiológica/fisiologia , Chlorella/crescimento & desenvolvimento , Microalgas/crescimento & desenvolvimento , Oxigênio/metabolismo , Taxa Respiratória
3.
Chemosphere ; 238: 124573, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31454741

RESUMO

This study investigated the nutrient content and reuse potential of wastewater generated during hydrothermal liquefaction of microalgal biomass. The hydrothermal liquefaction reaction was tested at 270, 300, 330, and 345 °C to determine the effect of temperature on the formation of non-biodegradable dissolved organic nitrogen (nbDON). Total nitrogen, ammonium, color, and toxicity were selected as key characteristics for the reuse of hydrothermal liquefaction wastewater. Results indicated that a higher concentration of nbDON5 (nbDON defined with a 5 day growth assay) and more diverse heterocyclic N-containing organic compounds were associated with greater toxicity as measured by a growth rate assay. For the tested temperature ranges, the total nitrogen content of the hydrothermal liquefaction wastewater slightly decreased from 5020 ±â€¯690 mg L-1 to 4160 ±â€¯120 mg L-1, but the % nbDON5 fraction increased from 57 ±â€¯3 %DON to 96 ±â€¯5 %DON. The temperature of hydrothermal liquefaction reactions can be optimized to maximize carbon conversion and nitrogen recovery.


Assuntos
Chlorella/crescimento & desenvolvimento , Microalgas/crescimento & desenvolvimento , Compostos de Nitrogênio/toxicidade , Compostos Orgânicos/toxicidade , Águas Residuárias/toxicidade , Biodegradação Ambiental , Biocombustíveis , Biomassa , Nitrogênio/análise , Compostos de Nitrogênio/metabolismo , Compostos Orgânicos/análise , Temperatura Ambiente , Águas Residuárias/química
4.
Huan Jing Ke Xue ; 40(7): 3108-3117, 2019 Jul 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854708

RESUMO

To understand the influence of rainfall on the in situ growth (in a culture cage) of dominant algae species in the Xiangxi River tributary of the Three Gorges Reservoir, culture experiments were carried out to measure the biomass of Microcystis aeruginosa, Chlorella vulgaris, and Chlorella aeruginosa before and after rainfall. The results showed that ① during the study period (October 4-18, 2017), there were significant differences in hydrodynamic conditions between the rainfall period and the non-rainfall period (ANOVA, P<0.05). Total Chl-a and the specific growth rate of the three main algae during rainfall period were significantly lower than during the non-rainfall period, which inhibited algae growth to some extent. The results of correlation analysis showed that the four hydrodynamic parameters characterizing vertical mixing had a highly significant negative correlation with the specific growth rate of the three dominant algae species. Meanwhile, the changes of shear force τ, the vertical turbulent viscosity coefficient Vr, and the vertical turbulent diffusion coefficient Vt were the key factors leading to the rapid decline of algae; ② the depth of the mixed layer was lower (1-2 m) before rainfall, but increased (>5 m) markedly after rainfall (October 10-18). At the same time, the concentration of Chl-a during the rainfall period was significantly lower than that during the non-rainfall period. The results of the correlation analysis showed that there was a highly significant positive correlation between the ratio of eutrophic depth to mixing depth (Zeu/Zmix) and the specific growth rate of the three dominant algae species. This indicated that the vertical disturbance of water was enhanced by rainfall, and mixing layer expanded continuously, which reduced the water temperature stratification and thus inhibited the growth and proliferation of algae; ③ there were significant differences in rainfall, water temperature, light intensity, total nitrogen, and dissolved total nitrogen between the rainfall period and non-rainfall period (ANOVA, P<0.05). Correlation analysis showed that changes in rainfall, water temperature, light intensity, total nitrogen, and dissolved total nitrogen caused by rainfall were the key environmental parameters affecting the in situ growth rate of three dominant algae.


Assuntos
Chlorella/crescimento & desenvolvimento , Microcystis/crescimento & desenvolvimento , Chuva , Rios , Biomassa , China , Clorofila A/análise , Nitrogênio/análise
5.
Aquat Toxicol ; 216: 105295, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561136

RESUMO

Oxybenzone (OBZ; benzophenone-3, CAS# 131-57-7) is a known pollutant of aquatic and marine ecosystems, and is an ingredient in over 3000 personal care products, as well as many types of plastics. The aim of this study is to explore the different toxicities of OBZ on an eukaryotic (Chlorella sp.) and a prokaryotic algae (Arthrospira sp.). OBZ is a photo-toxicant, with all observed toxicities more sever in the light than in the dark. Cell growth and chlorophyll inhibition were positively correlated with increasing OBZ concentrations over time. Twenty days treatment with OBZ, as low as 22.8 ng L-1, significantly inhibited the growth and chlorophyll synthesis of both algae. Both algae were noticeably photo-bleached after 7 days of exposure to OBZ concentrations higher than 2.28 mg L-1. Relatively low OBZ concentrations (0.228 mg L-1) statistically constrained photosynthetic and respiratory rates via directly inhibiting photosynthetic electron transport (PET) and respiration electron transport (RET) mechanisms, resulting in over production of reactive oxygen species (ROS). Transmission and scanning electron microscopy showed that the photosynthetic and respiratory membrane structures were damaged by OBZ exposure in both algae. Additionally, PET inhibition suppressed ATP production for CO2 assimilation via the Calvin-Benson cycle, further limiting synthesis of other biomacromolecules. RET restriction limited ATP generation, restricting the energy supply used for various life activities in the cell. These processes further impacted on photosynthesis, respiration and algal growth, representing secondary OBZ-induced algal damages. The data contained herein, as well as other studies, supports the argument that global pelagic and aquatic phytoplankton could be negatively influenced by OBZ pollution.


Assuntos
Benzofenonas/toxicidade , Chlorella/efeitos dos fármacos , Cosméticos/toxicidade , Spirulina/efeitos dos fármacos , Protetores Solares/toxicidade , Trifosfato de Adenosina/metabolismo , Respiração Celular/efeitos dos fármacos , Forma Celular/efeitos dos fármacos , Chlorella/crescimento & desenvolvimento , Chlorella/ultraestrutura , Clorofila/metabolismo , Transporte de Elétrons/efeitos dos fármacos , Luz , Fotossíntese/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Spirulina/crescimento & desenvolvimento , Spirulina/ultraestrutura , Fatores de Tempo , Poluentes Químicos da Água/toxicidade
6.
J Biosci ; 44(4)2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31502567

RESUMO

Constantly rising energy demands, finite fossil fuel reserves and deteriorating environmental conditions have invoked worldwide interest to explore the sustainable sources of renewable biofuels. Locally adapted photosynthetic oleaginous microalgae with rapid growth on variable temperatures could be an ideal way for bioremediating the wastewater (WW) while producing the feedstock for biodiesel. To test this notion, an unknown strain was isolated from a sewage fed lake (Neela-Hauz). It was discerned as Chlorella sorokiniana-I using the 16S rDNA and 18S rDNA barcodes. The culture conditions such as pH, illumination, different temperature ranges and growth medium were cohesively optimized prior to the assessment of C. sorokiniana-I's efficacy to remediate the WWand biodiesel production. The strain has thrived well up to 40°C when continuously grown for 15 days. The highest lipid accumulation and biomass productivity were recorded in 100% WW. Fatty acid methyl ester (FAME) content was observed to be more than twice in WW (47%), compared to control synthetic media, TAP (20%) and BG11 (10%), which indicate the importance of this new isolate for producing economically viable biodiesel. Moreover, it is highly efficient in removing the total nitrogen (77%), total phosphorous (81%), iron (67%) and calcium (42%) from the WW. The quality of WW was considerably improved by reducing the overall chemical oxygen demand (48%), biological oxygen demand (47%) and alkalinity (15%). Thus, C. sorokiniana-I could be an ideal alga for the tropical countries in the remediation of WW while producing feedstock for biodiesel in a cost-effective manner.


Assuntos
Biodegradação Ambiental , Chlorella/genética , Recuperação e Remediação Ambiental , Estágios do Ciclo de Vida/genética , Biocombustíveis , Biomassa , Chlorella/crescimento & desenvolvimento , Chlorella/metabolismo , Meios de Cultura , Ácidos Graxos/química , Ácidos Graxos/genética , Humanos , Lipídeos/química , Lipídeos/genética , Microalgas , Nitrogênio/metabolismo , Águas Residuárias/química
7.
Bioresour Technol ; 291: 121783, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31326682

RESUMO

Microalgae are feedstocks for multiple product development based on algal biorefinery concept. The effects of light quality (white, red and blue light emitting diodes) and macro-element starvations on Chlorella sp. AE10 were investigated under 20% CO2 and 850 µmol m-2 d-1. Nitrogen and phosphorus starvations had negative effects on its growth rate. The biomass productivities were decreased from day 1 and the highest one was 1.90 g L-1 d-1 under white light conditions. Phosphorus starvation promoted carbohydrate accumulation under three LED light sources conditions and the highest carbohydrate content was 75.9% using red light. Blue light increased lutein content to 9.58 mg g-1. The content of saturated fatty acids was significantly increased from 37.51% under blue light and full culture medium conditions to 77.44% under blue light and nitrogen starvation conditions. Chlorella sp. AE10 was a good candidate for carbohydrate and lutein productions.


Assuntos
Carboidratos/biossíntese , Chlorella/metabolismo , Ácidos Graxos/biossíntese , Luteína/biossíntese , Biomassa , Chlorella/crescimento & desenvolvimento , Ácidos Graxos/análise , Luz , Nitrogênio/metabolismo , Fósforo/metabolismo
8.
Bioresour Technol ; 291: 121820, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31344639

RESUMO

Mixotrophy (M) assumes sum of autotrophic (A) and heterotrophic (H) growths. In this study, a novel split-mixotrophic cultivation strategy (SMCS) developed as better mixotrophy via offering mutual-benefits through gas-exchange at both headspaces while splitting both trophic modes. To quantify synergistic-growth effects in combined-autotrophy and combined-heterotrophy (CA&CH) of SMCS, gross O2-evolution, DIC and DO concentrations were compared with A, H and M. Average 12-14% and 26-32% increase in DIC and DO concentrations were determined respectively in CA and CH than A, H and M. Biomass yield in CA + CH was increased approx.1.5-folds higher than yields of A + H and M regimes. These results show SMCS as better cultivation strategy than the M by increased biomass and lipid yields. Challenges associated with organic carbon can be solved by SMCS viz. chlorophyll loss, organic carbon uptake inhibition. SMCS could be a breakthrough to integrate bacterial process with algae for better bioprocess economy and energy recovery.


Assuntos
Biomassa , Chlorella/metabolismo , Lipídeos/biossíntese , Processos Autotróficos , Chlorella/crescimento & desenvolvimento , Clorofila/metabolismo , Processos Heterotróficos
9.
Bioprocess Biosyst Eng ; 42(9): 1409-1419, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31321529

RESUMO

Microbial biomass which mostly generated from the microbial processes of bacteria, yeasts, and microalgae is an important resource. Recent concerns in microbial biomass production field, especially microbial lipid production for biofuel, have been focused towards the mixed culture of microalgae and yeast. To more comprehensive understanding of the mixed culture for microbial biomass, mono Chlorella pyrenoidosa, mono Yarrowia lipolytica and the mixed culture were investigated in the present work. Results showed that the mixed culture achieved significantly faster cell propagation of microalga and yeast, smaller individual cell size of yeast and higher relative chlorophyll content of microalga. The mixed culture facilitated the assimilation of carbon and nitrogen and drove the carbon flow to carbohydrate. Besides higher lipid yield (0.77 g/L), higher yields of carbohydrates (1.82 g/L), protein (1.99 g/L) and heating value (114.64 kJ/L) indicated the microbial biomass harvested from the mixed culture have more potential utilization in renewable energy, feedstuff, and chemical industry.


Assuntos
Biomassa , Chlorella/crescimento & desenvolvimento , Lipídeos/biossíntese , Microalgas/crescimento & desenvolvimento , Yarrowia/crescimento & desenvolvimento
10.
Microb Cell Fact ; 18(1): 113, 2019 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-31253148

RESUMO

BACKGROUND: Microalgae have been proposed as potential platform to produce lipid-derived products, such as biofuels. Knowledge on the intracellular carbon flow distribution may identify key metabolic processes during lipid synthesis thus refining culture/genetic strategies to maximize cell lipid productivity. A kinetic metabolic model simulating cell metabolic behavior and lipid production was first applied in the microalgae platform Chlorella protothecoides under heterotrophic condition. It combines both physiology and flux information in a kinetic approach. Cell nutrition, growth, lipid production and almost 30 metabolic intermediates covering central carbon metabolism were included and simulated. RESULTS: Model simulations were shown to adequately agree with experimental data, which is suggesting that the proposed model copes with Chlorella protothecoides cells' biology. The dynamic metabolic flux analysis using the model showed a reversible starch flux from accumulation to decomposing when glucose reached depletion, while net lipid flux shows a quasi-constant rate. The sensitive flux parameters on starch and lipid metabolism suggested that starch synthesis is the major competing pathway that affects lipid accumulation in C. protothecoides. Flux analysis also demonstrated that high lipid yield under heterotrophic condition is accompanied with high lipid flux and low TCA activity. Meanwhile, the dynamic flux distribution also suggests a relatively constant ratio of glucose distributed to biomass, lipid, starch, nucleotides as well as pentose phosphate pathway. CONCLUSION: The model described not only experimental data, but also unraveled intracellular carbon flow distribution and identify key metabolic processes during lipid synthesis. Most of the metabolic kinetics also showed statistical significance for metabolic mechanism. Therefore, this study unravels the mechanisms of the glucose impact on the dynamic carbon flux distribution, thus improving our understanding of the links between carbon fluxes and lipid metabolism in C. protothecoides.


Assuntos
Chlorella/metabolismo , Lipídeos/biossíntese , Lipídeos/química , Carbono/metabolismo , Chlorella/química , Chlorella/crescimento & desenvolvimento , Glucose/metabolismo , Processos Heterotróficos , Cinética , Análise do Fluxo Metabólico , Microalgas/química , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , Via de Pentose Fosfato , Amido/metabolismo
11.
J Appl Microbiol ; 127(2): 481-494, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31141277

RESUMO

AIM: The aim of present work was to explore the potential of Chlorella sp. SRD3 extracts for antioxidant and antibacterial activity along with the evaluation of minimum inhibitory concentration (MIC) and haemolytic activity to detect RBC cell damage. METHODS AND RESULTS: Screening and isolation of microalgae was performed using bold basal medium under normal illuminance (at 27°C) and microscopic observation. Growth of the microalgae was optimized using a different medium and light source. The isolated microalgae incubated under fluorescent light when cultured in F/2 medium showed a highest dry biomass yield of 3·77 ± 0·1 g l-1 , when compared to the growth under direct sunlight (2·74 ± 0·07 g dwt l-1 ). The quantitative analysis of extracts revealed higher phenols, flavonoids and proanthocyanidins in ethyl acetate and hexane extracts followed by methanol. The antioxidant activity of extracts was tested against 1-diphenyl-2-picrylhydrazyl and ABTS radical, its reducing power assay was performed. From antibacterial activity, the two extracts showed better inhibition against Gram-negative bacteria. Also, they resulted in very low MIC values with effective activity against pathogens. In haemolytic activity, no haemolysis occurred, when the concentration (µg ml-1 ) was below 64 for methanol and 32 for ethyl acetate extract. In addition, Chlorella sp. extracts were characterized by GC-MS analysis to detect the major compounds. CONCLUSION: The polar extracts revealed satisfactory results against the clinical isolates and the compounds responsible were reflected in the GC-MS spectrum. SIGNIFICANCE AND IMPACT OF THE STUDY: The present study revealed significant biological potentials of the green alga, Chlorella sp. such as antioxidant, antibacterial and hemolytic activities. Therefore, this vital source might serve as a cost-effective, alternative choice to the pharmaceutical and food industries in the near future.


Assuntos
Antibacterianos/farmacologia , Chlorella , Depuradores de Radicais Livres/farmacologia , Antibacterianos/química , Chlorella/química , Chlorella/crescimento & desenvolvimento , Flavonoides/análise , Depuradores de Radicais Livres/química , Bactérias Gram-Negativas/efeitos dos fármacos , Hemolíticos/farmacologia , Humanos , Fenóis/análise , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Proantocianidinas/análise
12.
Environ Pollut ; 252(Pt A): 103-109, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31146223

RESUMO

The 6:2 chlorinated polyfluoroalkyl ether sulfonic acids (6:2 Cl-PFAES), 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)-propanoic acid (HFPO-DA) and perfluoroethylcyclohexane sulfonate (PFECHS) are emerging per- and polyfluoroalkyl substances (PFASs) that are being applied to replace phased-out PFASs, which have high persistency, high bioaccumulation potential and high toxicity. Recently, these emerging PFASs were observed in estuary and marine areas with a pollution level of ng/L. In this study, three levels (10 ng L-1, 100 ng L-1 and 1000 ng L-1) for these PFASs were selected to investigate the response of marine Chlorella sp. to 14 days of exposure. The growth of Chlorella sp. was significantly inhibited by each PFAS over time. Treatments with 1000 ng/L exposure caused the most severe reduction in growth for each PFAS treatment. For the first half of the experimental period (from Day 0 to Day 6), the influence of each PFAS was not significant (p > 0.05). However, treatments with all concentrations of 6:2 Cl-PFAES, HFPO-DA and 1000 ng L-1 PFECHS significantly reduced the growth of Chlorella sp. from Day 8. The superoxide dismutase (SOD) activities in Chlorella sp. were significantly increased (p < 0.05) when exposed to 6:2 Cl-PFAES, HFPO-DA and PFECHS. The catalase (CAT) and peroxidase (POD) activities in Chlorella sp. were significantly inhibited (p < 0.05) by each PFAS. The glutathione (GSH) contents in Chlorella sp. were significantly increased by each PFAS. However, the increases in GSH concentration in Chlorella sp. were low. The inhibition of algal growth was primarily due to the reduction of the activities of CAT and POD. PFECHS had the lowest toxicity among the three PFASs, and it induced less oxidized damage to Chlorella sp. In conclusion, as alternatives to phased-out PFASs, the emerging PFASs are not safe in aquatic environment, and attention should be paid to the management and restriction of these emerging PFASs.


Assuntos
Chlorella/crescimento & desenvolvimento , Chlorella/metabolismo , Fluorcarbonetos/toxicidade , Propionatos/toxicidade , Ácidos Sulfônicos/toxicidade , Poluentes Químicos da Água/toxicidade , Catalase/metabolismo , Estuários , Glutationa/análise , Peroxidase/metabolismo , Superóxido Dismutase/metabolismo
13.
Biotechnol Lett ; 41(4-5): 533-545, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30993480

RESUMO

OBJECTIVE: Microalgae gained interest for potential use as biodiesel producers, since they synthesize and accumulate significant quantities of lipids. The aim of this work was to isolate indigenous microalgae strains from Greek habitats, study their physicochemical growth conditions and finally select the best ones with respect to overall lipid production and profile. RESULTS: Two sampling sites of marine aquatic ecosystems were selected in Attica prefecture, Greece in order to screen for novel wild type strains with lipid production capacity. Microalgae isolates (59) were obtained from the selected areas and were morphologically and molecularly characterized. Fatty acids were estimated through Flow Cytometry combined with BODIPY staining method. Four isolates were selected for their lipid production properties and were cultivated in 15 L tank cultures. The four isolates were also identified by 18S rDNA gene sequencing. Two of them, Chlorella sp. ΑCΑ9 and ACA17, exhibited both maximum biomass and lipid productivity. Optimization of growth conditions with respect to pH and initial NaNO3 concentration was performed for the two microalgae in 15 L cultures. Finally, 20 L fed batch cultures were set up using the optimum culture conditions. Lipid profiles were stabilized for both strains at dry biomass levels over 1 g L-1 and lipid content of 25% (w/w). CONCLUSIONS: Two Chlorella strains (ACA9 and ACA17) were promising candidates for biodiesel production as they were easily grown in sea water in fed batch systems and produce lipids suitable for biodiesel-especially Chlorella sp. ACA9.


Assuntos
Biocombustíveis/microbiologia , Chlorella/metabolismo , Metabolismo dos Lipídeos , Lipídeos/isolamento & purificação , Chlorella/classificação , Chlorella/crescimento & desenvolvimento , Chlorella/isolamento & purificação , Análise por Conglomerados , Meios de Cultura/química , DNA de Plantas/química , DNA de Plantas/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Grécia , Filogenia , RNA Ribossômico 18S/genética , Análise de Sequência de DNA
14.
J Sci Food Agric ; 99(11): 5044-5049, 2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-30980414

RESUMO

BACKGROUND: It is evident that, during the conversion of agricultural sidestreams into valuable substances, a complete utilization is necessary for economic reasons. The present study investigated the transformation of defatted rice bran into proteins (single cell and extracted protein), soluble and insoluble dietary fiber, and minerals. RESULTS: In a process chain, starch/glucose was enzymatically extracted and converted into single cell protein (Chlorella sorokiniana). Then, rice bran proteins were extracted and partially precipitated. The remaining liquid was ultrafiltered (3 kDa) to obtain a further protein fraction and minerals. The protein fraction contained a considerable amount of soluble dietary fiber. With these steps, around 69% of the rice bran was transformed, resulting in three protein fractions with an average purity of approximately 45% and minerals with a purity of approximately 63%. In a subsequent process, the remaining cake was disintegrated at 95 °C and pH 2. A further 12% of the rice bran could be liquefied. After centrifugation, the supernatant was subjected to ultrafiltration (3 kDa) to obtain soluble dietary fiber in the retentate and minerals in the permeate. However, only around 2% of the rice bran was converted into soluble dietary fiber, whereas the remainder comprised a mixture of minerals and monomeric sugars. CONCLUSION: The process chain can be rearranged and optimized especially to increase the output of soluble dietary fiber and proteins as a result of using the digested monomeric sugars for algae cultivation. At the end of the process, 18% of rice bran remained as an insoluble dietary fiber fraction. © 2019 Society of Chemical Industry.


Assuntos
Chlorella/metabolismo , Fibras na Dieta/metabolismo , Minerais/metabolismo , Oryza/química , Chlorella/crescimento & desenvolvimento , Fibras na Dieta/análise , Minerais/análise , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Amido/análise , Amido/metabolismo , Resíduos/análise
15.
Environ Sci Pollut Res Int ; 26(16): 16115-16124, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30972671

RESUMO

The present study reports the use of Citrus limetta (CL) residue for cultivating Chlorella sp. mixotrophically to augment production of biodiesel. The cultivation of Chlorella sp. using CL as media was carried out by employing a fed-batch technique in open tray (open tray+CL) and in software (BioXpert V2)-attached automated photobioreactor (PBR+CL) systems. Data showed the limit of nitrogen substituent and satisfactory organic source of carbon (OSC) in CL, causing > 2-fold higher lipid content in cells, cultivated in both the systems than in control. For the cells grown in both the systems, ≥ 3-fold enhancement in lipid productivity was observed than in control. The total fatty acid methyl ester (FAME) concentrations from lipids extracted from cells grew in PBR+CL and in open tray+CL techniques were calculated as 50.59% and 38.31%, respectively. The PBR+CL system showed improved outcomes for lipid content, lipid and biomass productivity, FAME characteristics and physical property parameters of biodiesel than those obtained from the open tray+CL system. The physical property parameters of biodiesel produced from algal cells grown in PBR+CL were comparable to existing fuel standards. The results have shown lower cold filter plugging point (- 6.57 °C), higher cetane number (58.04) and average oxidative stability (3.60 h). Collectively, this investigation unveils the novel deployment of CL as a cost-effective feedstock for commercialisation of biodiesel production.


Assuntos
Biocombustíveis , Biotecnologia/métodos , Chlorella/crescimento & desenvolvimento , Citrus , Resíduos Industriais , Técnicas de Cultura Celular por Lotes , Biocombustíveis/análise , Biomassa , Biotecnologia/instrumentação , Carbono/metabolismo , Chlorella/metabolismo , Esterificação , Ácidos Graxos/análise , Ácidos Graxos/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Metabolismo dos Lipídeos , Lipídeos/análise , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , Nitrogênio/metabolismo , Fotobiorreatores
16.
Environ Sci Pollut Res Int ; 26(16): 16195-16209, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30972683

RESUMO

CO2, SO2, and NO are the main components of flue gas and can cause serious environmental issues. Utilization of these compounds in oleaginous microalgae cultivation not only could reduce air pollution but could also produce feedstock for biodiesel production. However, the continuous input of SO2 and NO inhibits microalgal growth. In this study, the toxicity of simulated flue gas (15% CO2, 0.03% SO2, and 0.03% NO, balanced with N2) was reduced through automatic pH feedback control. Integrated lipid production and CO2 fixation with the removal of SO2 and NO was achieved. Using this technique, a lipid content of 38.0% DW was achieved in Chlorella pyrenoidosa XQ-20044. The lipid composition and fatty acid profile indicated that lipid production by C. pyrenoidosa XQ-20044 cultured with flue gas is suitable as a biodiesel feedstock; 81.2% of the total lipids were neutral lipids and 99.5% of the total fatty acids were C16 and C18. The ratio of saturated fatty acids to monounsaturated fatty acids in the microalgal lipid content was 74.5%. In addition, CO2, SO2, and NO from the simulated flue gas were fixed and converted to biomass and lipids with a removal efficiency of 95.9%, 100%, and 84.2%, respectively. Furthermore, the utilization efficiencies of CO2, SO2, and NO were equal to or very close to their removal efficiencies. These results provide a novel strategy for combining biodiesel production with biofixation of flue gas.


Assuntos
Biotecnologia/métodos , Chlorella/efeitos dos fármacos , Chlorella/metabolismo , Lipídeos/biossíntese , Poluentes Atmosféricos/química , Poluentes Atmosféricos/isolamento & purificação , Poluentes Atmosféricos/toxicidade , Biocombustíveis , Biomassa , Biotecnologia/instrumentação , Dióxido de Carbono/isolamento & purificação , Dióxido de Carbono/toxicidade , Chlorella/crescimento & desenvolvimento , Ácidos Graxos/análise , Ácidos Graxos/metabolismo , Concentração de Íons de Hidrogênio , Microalgas/efeitos dos fármacos , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , Óxido Nítrico/isolamento & purificação , Óxido Nítrico/toxicidade , Dióxido de Enxofre/isolamento & purificação , Dióxido de Enxofre/toxicidade
17.
Ecotoxicol Environ Saf ; 174: 377-383, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30849658

RESUMO

17ß-estradiol (E2) is a steroid estrogen able to affect the reproduction of aquatic organisms even at extremely low concentrations. The behavior of E2 in the presence of chlorella algae was investigated in laboratory experiments. The results showed that the algae's growth was inhibited by 26% after 7 days of culturing in a 2.0 mg L-1 solution of E2. The 96 h EC50 value of 21.46 mg L-1 reflected moderate toxicity. Even low concentrations of E2 were found to affect total chlorophyll and carotenoid levels after 7 and 10 days and to alter stress-generated enzymatic activity in the algae. The efficiency of chlorella's E2 degradation decreased with the increasing of E2 concentration, but 92% of the E2 can be removed from a 0.5 mg L-1 solution over 10 days. The degradation mechanism was speculated. The microalgae suffered relatively less growth inhibition at low E2 concentrations, and their removal effectiveness was then better. The data help to elucidate the interaction between chlorella algae and E2 in an aquatic environment.


Assuntos
Chlorella/efeitos dos fármacos , Estradiol/análise , Microalgas/efeitos dos fármacos , Poluentes Químicos da Água/análise , Antioxidantes/metabolismo , Biodegradação Ambiental , Carotenoides/metabolismo , Chlorella/crescimento & desenvolvimento , Chlorella/metabolismo , Clorofila/metabolismo , Ecotoxicologia , Estradiol/toxicidade , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , Modelos Teóricos , Poluentes Químicos da Água/toxicidade
18.
Bioprocess Biosyst Eng ; 42(7): 1129-1142, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30919105

RESUMO

Microalgal lipid production by Chlorella protothecoides using sugarcane bagasse hydrolysate was investigated in this study. First, maximum glucose and reducing sugar concentrations of 15.2 and 27.0 g/L were obtained in sugarcane bagasse hydrolysate (SCBH), and the effects of different percentages of glucose and xylose on algal cultivation were investigated. Afterwards, SCBH was used as a carbon source for the cultivation of C. protothecoides and higher biomass concentration of 10.7 g/L was achieved. Additionally, a large amount of fatty acids, accounting up to 16.8% of dry weight, were accumulated in C. protothecoides in the nitrogen-limited (0.1-1 mmol/L) culture. Although SCBH inhibited fatty acid accumulation to a certain degree and the inhibition was aggravated by nitrogen starvation, SCBH favored microalgal cell growth and fatty acid production. The present study is of significance for the integration of cost-effective feedstocks production for biodiesel with low-cost SCBH as well as environmentally friendly disposal of lignocellulosic wastes.


Assuntos
Biocombustíveis , Biomassa , Celulose/química , Chlorella/crescimento & desenvolvimento , Ácidos Graxos/biossíntese , Saccharum/química
19.
Bioprocess Biosyst Eng ; 42(6): 971-978, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30830266

RESUMO

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


Assuntos
Biomassa , Chlorella/crescimento & desenvolvimento , Microalgas/crescimento & desenvolvimento , Polilisina/biossíntese , Floculação
20.
Sci Total Environ ; 667: 191-196, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30826679

RESUMO

A mild and low-energy cell disruption method with high efficiency has growing application potential in both the extraction of high-value microalgal products and the inactivation of microalgal cells. Conventional technologies available have disadvantages including high energy consumption, the use of chemicals and so on. Here, this study developed an efficient microalgal cell disruption method using the copper oxide nanowire (CuONW)-modified three-dimensional (3D) copper foam electrodes with a low applied voltage. Electrodes with nanowires synthesized at 400 °C, the optimal preparation temperature, achieved efficient microalgal cell electroporation. Microalgal cells were completely inactivated and disrupted at the voltage of 2 V with the hydraulic retention time (HRT) of 10 s. Scanning electron microscopy (SEM) images showed obvious electroporation damage on the cell surface upon electroporation-treatment (2 V, 30 s). The amount of released cellular inclusion increased significantly with prolonged HRT and the energy consumption of this technology was only 0.014 kWh/kg via the treatment of 2 V and 10 s. This study provided a novel, energy-efficient and chemical-free technique for both microalgal products extraction and cell inactivation.


Assuntos
Técnicas de Cultura de Células/métodos , Chlorella/fisiologia , Corpos de Inclusão/fisiologia , Microalgas/fisiologia , Nanofios/química , Chlorella/citologia , Chlorella/crescimento & desenvolvimento , Eletrodos , Eletroporação , Microalgas/citologia , Microalgas/crescimento & desenvolvimento
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