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1.
Nutrients ; 15(2)2023 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-36678348

RESUMO

It is estimated that by 2050, the world's population will exceed 10 billion people, which will lead to a deterioration in global food security. To avoid aggravating this problem, FAO and WHO have recommended dietary changes to reduce the intake of animal calories and increase the consumption of sustainable, nutrient-rich, and calorie-efficient products. Moreover, due to the worldwide rising incidence of non-communicable diseases and the demonstrated impact of diet on the risk of these disorders, the current established food pattern is focused on the consumption of foods that have functionality for health. Among promising sources of functional foods, microalgae are gaining worldwide attention because of their richness in high-value compounds with potential health benefits. However, despite the great opportunities to exploit microalgae in functional food industry, their use remains limited by challenges related to species diversity and variations in cultivation factors, changes in functional composition during extraction procedures, and limited evidence on the safety and bioavailability of microalgae bioactives. The aim of this review is to provide an updated and comprehensive discussion on the nutritional value, biological effects, and digestibility of two microalgae genera, Tetraselmis and Nannochloropsis, as basis of their potential as ingredients for the development of functional foods.


Assuntos
Clorófitas , Microalgas , Estramenópilas , Animais , Alimento Funcional
2.
Microb Cell Fact ; 22(1): 12, 2023 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-36647076

RESUMO

Microalgae are considered a suitable production platform for high-value lipids and oleochemicals. Several species including Nannochloropsis oceanica produce large amounts of essential [Formula: see text]-3 polyunsaturated fatty acids (PUFAs) which are integral components of food and feed and have been associated with health-promoting effects. N. oceanica can further accumulate high contents of non-polar lipids with chemical properties that render them a potential replacement for plant oils such as palm oil. However, biomass and lipid productivities obtained with microalgae need to be improved to reach commercial feasibility. Genetic engineering can improve biomass and lipid productivities, for instance by increasing carbon flux to lipids. Here, we report the overexpression of glycerol-3-phosphate acyltransferase (GPAT) in N. oceanica during favorable growth conditions as a strategy to increase non-polar lipid content. Transformants overproducing either an endogenous (NoGPAT) or a heterologous (Acutodesmus obliquus GPAT) GPAT enzyme targeted to the endoplasmic reticulum had up to 42% and 51% increased non-polar lipid contents, respectively, compared to the wild type. Biomass productivities of transformant strains were not substantially impaired, resulting in lipid productivities that were increased by up to 37% and 42% for NoGPAT and AoGPAT transformants, respectively. When exposed to nutrient stress, transformants and wild type had similar lipid contents, suggesting that GPAT enzyme exerts strong flux control on lipid synthesis in N. oceanica under favorable growth conditions. NoGPAT transformants further accumulated PUFAs in non-polar lipids, reaching a total of 6.8% PUFAs per biomass, an increase of 24% relative to the wild type. Overall, our results indicate that GPAT is an interesting target for engineering of lipid metabolism in microalgae, in order to improve non-polar lipid and PUFAs accumulation in microalgae.


Assuntos
Microalgas , Estramenópilas , Glicerol/metabolismo , Óleos/metabolismo , Engenharia Genética , Glicerol-3-Fosfato O-Aciltransferase/genética , Glicerol-3-Fosfato O-Aciltransferase/metabolismo , Estramenópilas/genética , Microalgas/genética , Microalgas/metabolismo , Biomassa , Fosfatos/metabolismo
3.
Environ Res ; 216(Pt 1): 114459, 2023 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-36181899

RESUMO

Brown tides caused by the pelagophyte Aureococcus anophagefferens have frequently occurred in the Bohai Sea since 2009 and have led to a dramatic collapse of the local scallop culture. To determine why brown tides occurred in the Bohai Sea rather than in other eutrophic coastal waters of China, phytoplankton communities and nutrients were evaluated and nutrient addition experiments were conducted in the Qinhuangdao coastal area. The concentration of dissolved organic nitrogen (DON) was nearly five times higher than that of dissolved inorganic nitrogen (DIN) during brown tides. High levels of phytoplankton biomass and nutrients were observed in the inshore waters, and the patterns of different nutrients were heterogeneous, which could be due to the uneven distribution of pelagophytes and non-brown tide phytoplankton populations (NBTP). The nutrient enrichment results indicated that the growth of the phytoplankton community was nitrogen-limited. Enrichment of DON, especially urea, could promote the growth of pelagophytes during the development stages of the brown tide. In brief, the results of this study imply that the unique nutrient profile (rich in DON but deficient in DIN) could support the outbreak of brown tides in the inshore waters of Qinhuangdao.


Assuntos
Fitoplâncton , Estramenópilas , Nitrogênio/análise , Nutrientes , Biomassa , China
4.
Bioresour Technol ; 370: 128536, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36581232

RESUMO

Due to growing health concerns, the urban population is utterly inclined towards a healthy lifestyle and incorporated nutritional food supplements to lower common health risks. The ω-3 and ω-6 PUFAs consumption is increasing, hence alternative commercial production is essentially developed. The microbial source is an emerging platform to overcome the global demand for omega PUFAs. Marine oleaginous protist Aurantiochytrium sp. found a potential source to produce substantial DHA and SFA. The objective of the present research was to enhance the PUFA yield by optimizing maximum tolerable glucose concentration with a suitable nitrogen ratio (10:1). The maximum lipid and DHA yield and content were determined 4.30, 1.34 g/L, and 62.4, 33.49 % of total biomass and lipid at 30 g/L glucose respectively, which is one of among highest reported, however relative PUFA was maximum 46.97 % (DHA) in total lipid at 10 g/L glucose. Remaining 42-53.6 % SFA could be used for biodiesel.


Assuntos
Ácidos Graxos Ômega-3 , Estramenópilas , Ácidos Docosa-Hexaenoicos , Ácidos Graxos Insaturados , Suplementos Nutricionais , Glucose , Ácidos Graxos
5.
Mar Drugs ; 20(12)2022 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-36547927

RESUMO

Aurantiochytrium is a heterotrophic marine microalga that has potential industrial applications. The main objectives of this study were to isolate an Aurantiochytrium strain from Sand Cay (Son Ca) Island, Vietnam, optimize its culture conditions, determine its nutritional composition, extract polyunsaturated fatty acids (PUFAs) in the free (FFA) and the alkyl ester (FAAE) forms, and evaluate the antioxidation and neuroprotection properties of the PUFAs. Aurantiochytrium sp. SC145 can be grown stably under laboratory conditions. Its culture conditions were optimized for a dry cell weight (DCW) of 31.18 g/L, with total lipids comprising 25.29%, proteins 7.93%, carbohydrates 15.21%, and carotenoid at 143.67 µg/L of DCW. The FAAEs and FFAs extracted from Aurantiochytrium sp. SC145 were rich in omega 3-6-9 fatty acids (40.73% and 44.00% of total fatty acids, respectively). No acute or subchronic oral toxicity was determined in mice fed with the PUFAs in FFA or FAAE forms at different doses over 90 days. Furthermore, the PUFAs in the FFA or FAAE forms and their main constituents of EPA, DHA, and ALA showed antioxidant and AChE inhibitory properties and neuroprotective activities against damage caused by H2O2- and amyloid-ß protein fragment 25-35 (Aß25-35)-induced C6 cells. These data suggest that PUFAs extracted from Aurantiochytrium sp. SC145 may be a potential therapeutic target for the treatment of neurodegenerative disorders.


Assuntos
Antioxidantes , Estramenópilas , Animais , Camundongos , Antioxidantes/farmacologia , Antioxidantes/metabolismo , Areia , Ácidos Docosa-Hexaenoicos/farmacologia , Ácidos Docosa-Hexaenoicos/metabolismo , Vietnã , Peróxido de Hidrogênio/metabolismo , Neuroproteção , Núcleo Familiar , Ácidos Graxos Insaturados/farmacologia , Ácidos Graxos Insaturados/metabolismo , Ácidos Graxos/metabolismo , Estramenópilas/metabolismo , Ácidos Graxos não Esterificados/metabolismo
6.
BMC Biotechnol ; 22(1): 39, 2022 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-36494804

RESUMO

Docosahexaenoic acid (DHA) can improve human and animal health, particularly including anti-inflammatory, antioxidant, anticancer, neurological, and visual functions. Schizochytrium sp. is a marine heterotrophic protist producing oil with high DHA content, which is widely used in animal and food production. However, different fermentation conditions have intensive impacts on the growth and DHA content of Schizochytrium sp. Thus, this study aimed to enhance the DHA yield and concentration of Schizochytrium sp. I-F-9 by optimizing the fermentation medium. First, a single-factor design was conducted to select a target carbon and nitrogen source from several generic sources (glucose, sucrose, glycerol, maltose, corn syrup, yeast extract, urea, peptone, and ammonium sulfate). The Plackett-Burman design and the central composite design (CCD) were utilized to optimize the fermentation mediums. Schizochytrium sp. in 50-mL fermentation broth was cultured in a 250 mL shake flask at 28 °C and 200 rpm for 120 h before collecting the cell pellet. Subsequently, the cell walls were destroyed with hydrochloric acid to extract the fatty acid using n-hexane. The DHA content was detected by gas chromatography. The single-factor test indicated that glucose and peptone, respectively, significantly improved the DHA content of Schizochytrium sp. compared to the other carbon and nitrogen sources. Glucose, sodium glutamate, and sea crystal were the key factors affecting DHA production in the Plackett-Burman test (P = 0.0247). The CCD result showed that DHA production was elevated by 34.73% compared with the initial yield (from 6.18 ± 0.063 to 8.33 ± 0.052 g/L). Therefore, the results of this study demonstrated an efficient strategy to increase the yield and content of DHA of Schizochytrium sp.


Assuntos
Ácidos Docosa-Hexaenoicos , Estramenópilas , Humanos , Fermentação , Nitrogênio , Carbono , Glucose
7.
Mar Drugs ; 20(12)2022 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-36547884

RESUMO

Nannochloropsis oculata is well-recognized as a potential microalgal source of valuable compounds such as polyunsaturated fatty acids, particularly, eicosapentaenoic acid (EPA). The content and profile of these lipids is highly dependent on the growth conditions and can, therefore, be tailored through modulation of the growth parameters, specifically, temperature. Moreover, biological activities are composition dependent. In the present work, lipid extracts obtained from N. oculata, grown under constant temperature and under modulated temperature stress (to increase EPA content; Str) were characterized by GC-FID and several bioactivities were evaluated, namely, antioxidant (L-ORACFL), cytotoxic (MTT), adipolytic, anti-hepatic lipid accumulation (steatosis), and anti-inflammatory properties. Both extracts exhibited antioxidant activity (c.a. 49 µmol Troloxequivalent/mgextract) and the absence of toxicity (up to 800 µg/mL) toward colon and hepatic cells, adipocytes, and macrophages. They also induced adipolysis and the inhibition of triglycerides hepatic accumulation, with a higher impact from Str. In addition, anti-inflammatory activity was observed in the lipopolysaccharide-induced inflammation of macrophages in the presence of either extract, since lower levels of pro-inflammatory interleukin-6 and interferon-ß were obtained, specifically by Str. The results presented herein revealed that modulated temperature stress may enhance the health effects of N. oculata lipid extracts, which may be safely utilized to formulate novel food products.


Assuntos
Microalgas , Estramenópilas , Triglicerídeos , Ácido Eicosapentaenoico , Ácidos Graxos Insaturados , Temperatura
8.
FEMS Microbiol Ecol ; 99(1)2022 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-36546573

RESUMO

Harmful algal blooms (HABs) attracted much attention due to their extensive ecological hazards and the increasing influences on global biogeochemical cycles with the intensification of human impact and global warming. Lysing algal cells with species-specific microbial algicide seemed to be promising to eliminate HABs, but the potential ecotoxicity was rarely studied. In this study, microcosms simulating Heterosigma akashiwo blooms were established to reveal the influences of a microbial algicide from Streptomyces sp. U3 on the biological, physicochemical parameters and bacterial community. The results showed that H. akashiwo bloom accumulated nitrite to a lethal dose, produced bio-labile DOM with widespread influences and enriched pathogenic Coxiella to a high abundance. Lysing H. akashiwo cells by microbial algicide induced a bacterial bloom, eliminated nitrite contamination, enhanced the recalcitrance of DOM, and restored bacterial population from a Gammaproteobacteria-dominant community during bloom back to an Alphaproteobacteria-dominant community similar to the non-bloom seawater. Succession of bacterial genera further suggested that the variation from algal exudates to lysates promoted the restoration of metabolic generalists, which redirected the carbon flow to a less ecologically impactive path. This study revealed the benefits of using microbial algicide to remediate the ecological hazards of HABs, which provided references for future application.


Assuntos
Dinoflagelados , Herbicidas , Estramenópilas , Humanos , Nitritos , Carbono , Proliferação Nociva de Algas
9.
Int J Mol Sci ; 23(21)2022 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-36362255

RESUMO

Mitochondrion-related organelles (MROs) are loosely defined as degenerated mitochondria in anaerobic and microaerophilic lineages. Opalinids are commonly regarded as commensals in the guts of cold-blooded amphibians. It may represent an intermediate adaptation stage between the conventional aerobic mitochondria and derived anaerobic MROs. In the present study, we sequenced and analyzed the MRO genome of Cepedea longa. It has a linear MRO genome with large inverted repeat gene regions at both ends. Compared to Blastocystis and Proteromonas lacertae, the MRO genome of C. longa has a higher G + C content and repeat sequences near the central region. Although three Opalinata species have different morphological characteristics, phylogenetic analyses based on eight concatenated nad genes indicate that they are close relatives. The phylogenetic analysis showed that C. longa clustered with P. lacertae with strong support. The 18S rRNA gene-based phylogeny resolved the Opalinea clade as a sister clade to Karotomorpha, which then further grouped with Proteromonas. The paraphyly of Proteromonadea needs to be verified due to the lack of MRO genomes for key species, such as Karotomorpha, Opalina and Protoopalina. Besides, our dataset and analyses offered slight support for the paraphyly of Bigyra.


Assuntos
Anuros , Estramenópilas , Animais , Filogenia , Anuros/genética , Estramenópilas/genética , Organelas/metabolismo , Mitocôndrias/genética
10.
Protist ; 173(6): 125914, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36270076

RESUMO

An angled twin-layer porous substrate photobioreactor (TL-PSBR) using LED light was designed to cultivate Nannochloropsis oculata. Flocculation and sedimentation by modification of pH to 11 were determined as the optimal method for harvesting the N. oculata inoculum. The following optimised parameters were found: tilt angle 15°, Kraft 220 g m-2 paper as substrate material, initial inoculum density of 12.5 g m-2, 140 µmol photons m-2 s-1 light intensity, and a light/dark cycle of 6:6 (h). Test cultivation for 14 days was performed under optimised conditions. The total dried biomass standing crop was 75.5 g m-2 growth area with an average productivity of 6.3 g m-2 d-1, the productivity per volume of used culture medium was 126.2 mg/L d-1, total lipid content 21.9% (w/w), and the highest productivity of total lipids was 1.33 g m-2 d-1. The dry algal biomass contained 3% eicosapentaenoic acid (w/w), 3.7% palmitoleic acid (w/w), and 513 mg kg-1 vitamin E. The optimisation of N. oculata cultivation on an angled TL-PSBR system yielded promising results, and applications for commercial products need to be further explored.


Assuntos
Microalgas , Estramenópilas , Fotobiorreatores , Porosidade , Biomassa , Luz
11.
J Agric Food Chem ; 70(43): 13922-13934, 2022 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-36264009

RESUMO

The malonyl-CoA:ACP transacylase (MAT) domain is responsible for the selection and incorporation of malonyl building blocks in the biosynthesis of polyunsaturated fatty acids (PUFAs) in eukaryotic microalgae (Schizochytrium) and marine bacteria (Moritella marina, Photobacterium profundum, and Shewanella). Elucidation of the structural basis underlying the substrate specificity and catalytic mechanism of the MAT will help to improve the yield and quality of PUFAs. Here, a methodology guided by molecular dynamics simulations was carried out to identify and mutate specificity-conferring residues within the MAT domain of Schizochytrium. Combining mutagenesis, cell-free protein synthesis, and in vitro biochemical assay, we dissected nearby interactions and molecular mechanisms relevant for binding and catalysis and found that the reorientation of the Ser154 Cß-Oγ bond establishes distinctive proton-transfer chains (His153-Ser154 and Asn235-His153-Ser154) for catalysis. Gln66 can be replaced by tyrosine to shorten the distance between His153 (Nε2) and Ser154 (Oγ), which facilitates a faster proton-transfer rate, allowing better use of acyl substrates than the wild type. Furthermore, we screened a mutant that displayed an 18.4% increase in PUFA accumulation. These findings provide important insights into the study of MAT through protein engineering and will benefit dissecting the molecular mechanisms of other PUFA-related catalytic domains.


Assuntos
Malonil Coenzima A , Estramenópilas , Malonil Coenzima A/metabolismo , Prótons , Proteína de Transporte de Acila S-Maloniltransferase/metabolismo , Aciltransferases/metabolismo , Estramenópilas/metabolismo , Ácidos Graxos Insaturados/metabolismo
12.
Mar Drugs ; 20(10)2022 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-36286445

RESUMO

Nitrogen deprivation is known to improve lipid accumulation in microalgae and thraustochytrids. However, the patterns of fatty acid production and the molecular mechanisms underlying the accumulation of unsaturated and saturated fatty acids (SFAs) under nitrogen starvation remain largely unknown for thraustochytrids. In this study, batch culture experiments under nitrogen replete and nitrogen starvation conditions were performed, and the changes in the transcriptome of Aurantiochytrium sp. PKU#SW8 strain between these conditions were investigated. Our results showed improved yields of total fatty acids (TFAs), total unsaturated fatty acids, and total SFAs under nitrogen starvation, which suggested that nitrogen starvation favors the accumulation of both unsaturated and saturated fatty acids in PKU#SW8. However, nitrogen starvation resulted in a more than 2.36-fold increase of SFAs whereas a 1.7-fold increase of unsaturated fatty acids was observed, indicating a disproportionate increase in these groups of fatty acids. The fabD and enoyl-CoA hydratase genes were significantly upregulated under nitrogen starvation, supporting the observed increase in the yield of TFAs from 2.63 ± 0.22 g/L to 3.64 ± 0.16 g/L. Furthermore, the pfaB gene involved in the polyketide synthase (PKS) pathway was significantly upregulated under nitrogen starvation. This suggested that the increased expression of the pfaB gene under nitrogen starvation may be one of the explanations for the increased yield of docosahexaenoic acid by 1.58-fold. Overall, our study advances the current understanding of the molecular mechanisms that underlie the response of thraustochytrids to nitrogen deprivation and their fatty acid biosynthesis.


Assuntos
Nitrogênio , Estramenópilas , Nitrogênio/metabolismo , Ácidos Docosa-Hexaenoicos , Policetídeo Sintases/metabolismo , Estramenópilas/metabolismo , Ácidos Graxos Insaturados/metabolismo , Ácidos Graxos/metabolismo , Enoil-CoA Hidratase/metabolismo
13.
Mar Pollut Bull ; 184: 114193, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36209535

RESUMO

Present study investigated composition and distribution of chromophytic phytoplankton in the Bohai Sea (BS) and the Yellow Sea (YS) by using rbcL genes. Bacillariophyceae, Haptophyceae and Pelagophyceae were the most abundant phytoplankton groups. Distinct phytoplankton communities were observed in the BS and the YS: offshore stations were dominated by bloom forming genera Thalassiosira and Skeletonema, while brown tide-forming species including Chrysochromulina spp. and Aureococcus anophagefferens were commonly found in the nearshore areas. Redundancy analysis showed that phosphate, temperature and silicic acid play key roles in structuring chromophytic phytoplankton, such as phytoplankton at nearshore stations were affected by nutrient runoff from adjacent rivers (Yellow River). Anthropogenic activities in the Bohai Sea and seasonal circulation of ocean currents may also contribute to shaping chromophytic phytoplankton communities. This study provides data support and foundational observations of chromophytic phytoplankton in the BS and the YS, and their responses to environmental gradients and human activities.


Assuntos
Diatomáceas , Estramenópilas , China , Fosfatos , Fitoplâncton/fisiologia , Ribulose-Bifosfato Carboxilase/genética , Rios , Ácido Silícico
14.
Proc Natl Acad Sci U S A ; 119(42): e2206738119, 2022 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-36219692

RESUMO

The accumulation of swimming microorganisms at surfaces is an essential feature of various physical, chemical, and biological processes in confined spaces. To date, this accumulation is mainly assumed to depend on the change of swimming speed and angular velocity caused by cell-wall contact and hydrodynamic interaction. Here, we measured the swimming trajectories of Heterosigma akashiwo (a biflagellate marine alga) near vertical and horizontal rigid boundaries. We observed that the probability of sharp turns is greatly increased near a vertical wall, resulting in significant changes in the distributions of average swimming speed, angular velocity, and rotational diffusivity near the wall (a quantity that has not previously been investigated) as functions of both distance from the wall and swimming orientation. These cannot be satisfactorily explained by standard hydrodynamic models. Detailed examination of an individual cell trajectory shows that wall contact by the leading flagellum triggers complex changes in the behavior of both flagella that cannot be incorporated in a mechanistic model. Our individual-based model for predicting cell concentration using the measured distributions of swimming speed, angular velocity, and rotational diffusivity agrees well with the experiment. The experiments and model are repeated for a cell suspension in a vertical plane, bounded above by a horizontal wall. The cell accumulation beneath the wall, expected from gyrotaxis, is considerably amplified by cell-wall interaction. These findings may shed light on the prediction and control of cell distribution mediated by gyrotaxis and cell-wall contact.


Assuntos
Flagelos , Modelos Biológicos , Hidrodinâmica , Estramenópilas , Natação
15.
Harmful Algae ; 118: 102322, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36195418

RESUMO

Fisheries damage caused by Chattonella red tide has been recorded in Southeast Asia. Molecular studies have clarified the presence of two species, Chattonella marina complex and Chattonella subsalsa in the region, unlike East Asia that had only C. marina complex. To elucidate the phylogeography of Chattonella in Asia, further phylogenetic and morphological examinations were carried out with 33 additional culture strains, including the strains isolated during a bloom of Chattonella sp. (up to 142 cells mL-1) that was associated with a wild fish mortality along the northeastern coast of Peninsular Malaysia in 2016, and those from Yellow Sea, where the Chattonella genotypes have not been determined. LSU rDNA and ITS2 trees showed five intrageneric clades in the genus Chattonella, which were clades I and II (C. subsalsa), clade III (C. marina complex) and two new clades, namely clade IV from Thailand and Malaysia, and clade V from Peninsular Malaysia. The positions of the two new clades were different in LSU rDNA and ITS2 trees. LSU rDNA divergences of clades IV and V from the other clades were ≥ 4.01% and ≥ 5.70%, while their ITS2 divergences were ≥ 7.44% and ≥ 16.43%, respectively. Three and five compensatory base changes (CBCs) were observed in the clades IV and V, respectively, when compared to each of their closest clade. Cells from clades IV and V showed similar morphology to C. marina complex and C. subsalsa clade II, including the presence of button-like granules on cell surface and oboe-shaped mucocysts. However, cell size, the number and shape of chloroplasts in Chattonella clades IV and V, and the non-stacked thylakoids penetrated the pyrenoid in C. subsalsa clade II, were distinctive. Based on the diagnostic chloroplast shape, we proposed the designation of clades IV and V to two new species, Chattonella tenuiplastida sp. nov. and Chattonella malayana sp. nov.


Assuntos
Estramenópilas , Animais , DNA Ribossômico , Peixes , Filogenia , Filogeografia , Estramenópilas/metabolismo
16.
J Oleo Sci ; 71(10): 1493-1500, 2022 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-36089403

RESUMO

Thraustochytrid, Aurantiochytrium sp., produces various lipids such as polyunsaturated and saturated fatty acids, carotenoids, and other hydrocarbons, which are useful in the fields of health foods, cosmetics, fine chemicals, and biofuels. Lignocellulosic biomass, which is abundant and cheap, is a promising feedstock for producing cheaper bulk and high-value-added products using Aurantiochytrium sp. However, the steam explosion of lignocellulosic biomass for efficient enzymatic saccharification generates substances that inhibit the growth of microorganisms. In this study, the inhibitory activities of these by-products on the growth and lipid production of Aurantiochytrium sp. were investigated. Aurantiochytrium sp. was found to be highly sensitive to furfural and vanillin and moderately sensitive to 5-hydroxymethylfurfural and syringaldehyde. Washing steam-exploded bagasse with water, followed by activated charcoal treatment, significantly reduced furfural, which was a major inhibitory component in the saccharified solution.


Assuntos
Saccharum , Estramenópilas , Biocombustíveis , Biomassa , Carotenoides , Celulose , Carvão Vegetal , Ácidos Graxos , Furaldeído , Vapor
17.
Mar Drugs ; 20(9)2022 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-36135741

RESUMO

Nannochloropsis oculata is a marine microalgal species with a great potential as food or feed due to its high pigment, protein and eicosapentaenoic acid contents. However, for such an application to be realized on a large scale, a biorefinery approach is necessary due to the high cost of microalgal biomass production. For example, techno economic analyses have suggested the co-production of food or feed with antioxidants, which can be extracted and supplied separately to the market. The aim of this study was to investigate the effect of cultivation conditions on the antioxidant capacity of Nannochlosopsis oculata extracts, derived with ultrasound-assisted extraction at room temperature, as well as the proximate composition and fatty acid profile of the biomass. A fractional factorial approach was applied to examine the effects of temperature (20-35 °C), pH (6.5-9.5) and light period (24:0, 12:12). At the end of each run, biomass was collected, washed with 0.5M ammonium bicarbonate and freeze-dried. Antioxidant capacity as gallic acid equivalents as well as pigment content were measured in the ethanolic extracts. Optimal conditions were different for productivity and biomass composition. Interesting results regarding the effect of light period (LP) and pH require further investigation, whereas the effect of moisture on the extraction process was confounded with biomass composition. Finally, further data is provided regarding the relation between chlorophyll content and apparent phenolic content using the Folin-Ciocalteu assay, in agreement with our previous work.


Assuntos
Microalgas , Estramenópilas , Antioxidantes/metabolismo , Biomassa , Clorofila/metabolismo , Ácido Eicosapentaenoico/metabolismo , Ácidos Graxos/metabolismo , Ácido Gálico/metabolismo , Concentração de Íons de Hidrogênio , Microalgas/metabolismo , Fotobiorreatores , Estramenópilas/metabolismo , Temperatura
18.
Toxins (Basel) ; 14(9)2022 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-36136516

RESUMO

Heterosigma akashiwo is the only raphidophyte described for Chilean waters. A recent 2021 fish-killing bloom event of this raphidophyte ignited scientific research, but the ichthyotoxic mechanism and environmental conditions that promote its growth are still unclear. This is the first study confirming the occurrence of H. akashiwo in Chilean waters on the basis of the region D1/D2 of the 28S ribosomal gene. The pigment signature of the CREAN_HA03 strain revealed chlorophyll-a, fucoxanthin, and violaxanthin as the most abundant pigments, but profiles were variable depending on culture and field conditions. A factorial temperature-salinity growth experiment showed a maximal growth rate of 0.48 d-1 at 17 °C and 35 in salinity, but reached a maximal cell abundance of ~50,000 cells mL-1 at 12 °C and 25 in salinity. The fatty acid profile included high levels of saturated (16:0) and polyunsaturated (18:4 ω3; 20:5 ω3) fatty acids, but superoxide production in this strain was low (~0.3 pmol O2- cell-1 h-1). The RTgill-W1 bioassay showed that the H. akashiwo strain was cytotoxic only at high cell concentrations (>47,000 cells mL-1) and after cell rupture. In conclusion, salmon mortality during H. akashiwo bloom events in Patagonian fjords is likely explained by the high production of long-chain PUFAs at high cell densities, but only in the presence of high ROS production.


Assuntos
Dinoflagelados , Estramenópilas , Animais , Clorofila , Estuários , Ácidos Graxos , Ácidos Graxos Insaturados , Proliferação Nociva de Algas , Espécies Reativas de Oxigênio , Estramenópilas/genética , Superóxidos
19.
Commun Biol ; 5(1): 983, 2022 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-36114260

RESUMO

The smallest phytoplankton species are key actors in oceans biogeochemical cycling and their abundance and distribution are affected with global environmental changes. Among them, algae of the Pelagophyceae class encompass coastal species causative of harmful algal blooms while others are cosmopolitan and abundant. The lack of genomic reference in this lineage is a main limitation to study its ecological importance. Here, we analysed Pelagomonas calceolata relative abundance, ecological niche and potential for the adaptation in all oceans using a complete chromosome-scale assembled genome sequence. Our results show that P. calceolata is one of the most abundant eukaryotic species in the oceans with a relative abundance favoured by high temperature, low-light and iron-poor conditions. Climate change projections based on its relative abundance suggest an extension of the P. calceolata habitat toward the poles at the end of this century. Finally, we observed a specific gene repertoire and expression level variations potentially explaining its ecological success in low-iron and low-nitrate environments. Collectively, these findings reveal the ecological importance of P. calceolata and lay the foundation for a global scale analysis of the adaptation and acclimation strategies of this small phytoplankton in a changing environment.


Assuntos
Ferro , Estramenópilas , Aclimatação/genética , Cromossomos , Genômica , Ferro/metabolismo , Nitratos/metabolismo , Oceanos e Mares , Fitoplâncton/genética , Fitoplâncton/metabolismo , Estramenópilas/genética
20.
Appl Microbiol Biotechnol ; 106(19-20): 6535-6549, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36069927

RESUMO

Nannochloropsis oceanica is a unicellular oleaginous microalga of emerging biotechnological interest with a sequenced, annotated genome, available transcriptomic and proteomic data, and well-established basic molecular tools for genetic engineering. To establish N. oceanica as a eukaryotic host for recombinant protein synthesis and develop molecular technology for vaccine production, we chose the viral surface protein 2 (VP2) of a pathogenic fish virus that causes infectious pancreatic necrosis as a model vaccine. Upon stable nuclear transformation of N. oceanica strain CCMP1779 with the codon-optimized VP2 gene, a Venus reporter fusion served to evaluate the strength of different endogenous promoters in transformant populations by qPCR and flow cytometry. The highest VP2 yields were achieved for the elongation factor promoter, with enhancer effects by its N-terminal leader sequence. Individual transformants differed in their production capability of reporter-free VP2 by orders of magnitude. When subjecting the best candidates to kinetic analyses of growth and VP2 production in photobioreactors, recombinant protein integrity was maintained until the early stationary growth phase, and a high yield of 4.4% VP2 of total soluble protein was achieved. The maximum yield correlated with multiple integrations of the expression vector into the nuclear genome. The results demonstrate that N. oceanica was successfully engineered to constitute a robust platform for high-level production of a model subunit vaccine. The molecular methodology established here can likely be adapted in a straightforward manner to the production of further vaccines in the same host, allowing their distribution to fish, vertebrates, or humans via a microalgae-containing diet. KEY POINTS: • We engineered N. oceanica for recombinant protein production. • The antigenic surface protein 2 of IPN virus could indeed be expressed in the host. • A high yield of 4.4% VP2 of total soluble protein was achieved in N. oceanica.


Assuntos
Vírus da Necrose Pancreática Infecciosa , Estramenópilas , Vacinas Virais , Animais , Peixes , Humanos , Vírus da Necrose Pancreática Infecciosa/genética , Proteínas de Membrana , Fatores de Alongamento de Peptídeos , Proteômica , Proteínas Recombinantes/genética , Estramenópilas/genética , Vacinação , Vacinas Virais/genética
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