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While oral probiotics show promise in treating inflammatory bowel disease, the primary challenge lies in sustaining their activity and retention within the inflamed gastrointestinal environment. In this work, we develop an engineered probiotic platform that is armed with biocatalytic and inflamed colon-targeting nanocoatings for multipronged management of IBD. Notably, we achieve the in situ growth of artificial nanocatalysts on probiotics through a bioinspired mineralization strategy. The resulting ferrihydrite nanostructures anchored on bacteria exhibit robust catalase-like activity across a broad pH range, effectively scavenging ROS to alleviate inflammation. The further envelopment with fucoidan-based shields confers probiotics with additional inflamed colon-targeting functions. Upon oral administration, the engineered probiotics display markedly improved viability and colonization within the inflamed intestine, and they further elicit boosted prophylactic and therapeutic efficacy against colitis through the synergistic interplay of nanocatalysis-based immunomodulation and probiotics-mediated microbiota reshaping. The robust and multifunctional probiotic platforms offer great potential for the comprehensive management of gastrointestinal disorders.
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Pyroptosis-based immunotherapy can escape drug resistance as well as inhibit metastasis. It is urgently required to develop a delivery platform to induce targeted tumor-specific pyroptosis for cancer immunotherapy. Herein, macrophages-based biohybrid microrobots (IDN@MC) are constructed with IR-macrophage and decitabine-loaded Metal-organic frameworks (DZNPs). The integration of fluorescence photosensitizers and pH-sensitive DZNPs endow the microrobots properties such as photothermal conversion, fluorescent navigation, targeted drug delivery, and controlled drug release. In light of the inherent tumor targeting, tumor accumulation of IDN@MC is facilitated. Due to the sustained release of decitabine from packaged DZNPs, the host macrophages are differentiated into M1 phenotypes to exert the tumor phagocytosis at the tumor site, directly transporting the therapeutic agents into cancer cells. With laser control, the rapid and durable caspase 3-cleaved gasdermin E (GSDME)-related tumor pyroptosis is achieved with combined photothermal-chemotherapy, releasing inflammatory factors such as lactate dehydrogenase and interleukin-18. Subsequently, the robust and adaptive immune response is primed with dendritic cell maturation to initiate T-cell clone expansion and modulation of the immune suppressive microenvironment, thus enhancing the tumor immunotherapy to inhibit tumor proliferation and metastasis. This macrophages-based biohybrid microrobot is an efficient strategy for breast cancer treatment to trigger photo-induced pyroptosis and augment the immune response.
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Neoplasias , Piroptose , Humanos , Decitabina , Imunoterapia , Macrófagos , Linhagem Celular Tumoral , Microambiente TumoralRESUMO
Melatonin (MT) plays important roles in plant disease response, but the mechanisms are largely unknown. Here, we show that MT functions in stomatal immunity in Panax notoginseng and Arabidopsis thaliana. Biochemical analyses showed that MT-induced stomatal closure plays a prominent role in preventing invasion of bacteria Pseudomonas syringe pv. tomato (Pst) DC3000 via activation of mitogen-activated protein kinase (MAPK) and NADPH oxidase-mediated reactive oxygen species production in P. notoginseng. The first putative phytomelatonin receptor 1 (PMTR1) is a plasma membrane protein required for perceiving MT signaling in stomatal closure and activation of MAPK. Biochemical and genetic tests found PMTR1 is essential for flg22- and MT-induced MAPK activation in a heterotrimeric GTP-binding protein Gα subunit GPA1-independent manner. GPA1 functions in the same genetic pathways of FLS2/BAK1 (Flagellin Sensing 2/Brassinosteroid Insensitive 1-associated kinase 1)- as well as PMTR1-mediated flg22 and MT signaling in stomatal closure. The stomata in pmtr1 are insensitive to MT and flg22, but the application of MT induces stomatal closure and reduces the bacterial growth in fls2 and bak1 plants, indicating that PMTR1 might be a downstream signaling component in FLS2- and BAK1-mediated stomatal immunity. In summary, our results (i) demonstrate that phytomelatonin functions in the priming of stomatal immunity and (ii) provide insights into the phytomelatonin signaling transduction pathway.
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Arabidopsis/imunologia , Melatonina/administração & dosagem , Panax notoginseng/imunologia , Imunidade Vegetal , Proteínas de Plantas/imunologia , Estômatos de Plantas/imunologia , Pseudomonas syringae/fisiologia , Proteínas de Arabidopsis/imunologiaRESUMO
In the present study, the effects of four different culture media on the growth, astaxanthin production and morphology of Haematococcus pluvialis LUGU were studied under two-step cultivation. The interactions between astaxanthin synthesis and secondary messengers, reactive oxygen species (ROS) and mitogen-activated protein kinases (MAPK) were also investigated. In the first green vegetative cell stage, maximal biomass productivity (86.54 mg L-1 day-1) was obtained in BBM medium. In the induction stage, the highest astaxanthin content (21.5 mg g-1) occurred in BG-11 medium, which was higher than in any other media. The expressions of MAPK and astaxanthin biosynthetic genes in BG-11 were higher than in any other media, whereas the ROS content was lower. Biochemical and physiological analyses suggested that the ROS, MAPK and astaxanthin biosynthetic gene expression was involved in astaxanthin biosynthesis in H. pluvialis under different culture media conditions. This study proposes a two-step cultivation strategy to efficiently produce astaxanthin using microalgae.
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Biomassa , Clorófitas/crescimento & desenvolvimento , Meios de Cultura , Sistemas do Segundo Mensageiro , Clorófitas/genética , Meios de Cultura/química , Meios de Cultura/farmacologia , MAP Quinases Reguladas por Sinal Extracelular/genética , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Xantofilas/biossíntese , Xantofilas/genéticaRESUMO
To further improve the ganoderic acid (GA) production, a novel integrated strategy by combining nitrogen limitation and calcium ion addition was developed. The effects of the integrated combination on the content of GA-T (one powerful anticancer compound), their intermediates (squalene and lanosterol) and on the transcription levels of GA biosynthetic genes in G. lucidum fermentation were investigated. The maximum GA-T content with the integrated strategy were 1.87 mg/ 100 mg dry cell weight, which was 2.1-4.2 fold higher than that obtained with either calcium ion addition or nitrogen limitation alone, and it is also the highest record as ever reported in submerged fermentation of G. lucidum. The squalene content was increased by 3.9- and 2.2-fold in this case compared with either individual strategy alone. Moreover, the transcription levels of the GA biosynthetic genes encoding 3-hydroxy-3-methyglutaryl coenzyme A reductase and lanosterol synthase were also up-regulated by 3.3-7.5 and 1.3-2.3 fold, respectively.
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Cálcio/metabolismo , Nitrogênio/metabolismo , Reishi/crescimento & desenvolvimento , Triterpenos/metabolismo , Cálcio/farmacologiaRESUMO
High-value metabolites, such as carotenoids, lipids, and proteins, are synthesized by microalgae and find applications in various fields, including food, health supplements, and cosmetics. However, the potential of the microalgal industry to serve these sectors is constrained by low productivity and high energy consumption. Environmental stressors can not only stimulate the accumulation of secondary metabolites in microalgae but also induce oxidative stress, suppressing cell growth and activity, thereby resulting in a decrease in overall productivity. Using melatonin (MT) under stressful conditions is an effective approach to enhance the productivity of microalgal metabolites. This review underscores the role of MT in promoting the accumulation of high-value metabolites and enhancing stress resistance in microalgae under stressful and wastewater conditions. It discusses the underlying mechanisms whereby MT enhances metabolite synthesis and improves stress resistance. The review also offers new perspectives on utilizing MT to improve microalgal productivity and stress resistance in challenging environments.
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Melatonina , Microalgas , Microalgas/metabolismo , Reguladores de Crescimento de Plantas , Melatonina/farmacologia , Melatonina/metabolismo , Águas Residuárias , Estresse Oxidativo , Biomassa , BiocombustíveisRESUMO
Introduction: This study investigated the lagged correlation between Baidu Index for influenza-related keywords and influenza-like illness percentage (ILI%) across regions in China. The aim is to establish a scientific foundation for utilizing Baidu Index as an early warning tool for influenza-like illness epidemics. Methods: In this study, data on ILI% and Baidu Index were collected from 30 provincial-level administrative divisions (PLADs) spanning April 2014 to March 2019. The Baidu Index was categorized into Overall Index, Ordinary Index, Prevention Index, Symptom Index, and Treatment Index based on search query themes. The lagged correlation between the Baidu Index and ILI% was examined through the cross-correlation function (CCF) method. Results: Correlating the Baidu Overall Index of 30 PLADs with ILI% revealed CCF values ranging from 0.46 to 0.86, with a median lag of 0.5 days. Subcategory analysis indicated that the Prevention Index and Symptom Index exhibited quicker responses to ILI%, with median lags of -9 and -0.5 days, respectively, compared to 0 and 3 days for the Ordinary and Treatment Indexes. The median lag days between the Baidu Index and the ILI% were earlier in the northern PLADs compared to the southern PLADs. Discussion: The Prevention and Symptom Indexes show promising predictive capabilities for influenza-like illness epidemics.
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Background: We aimed to evaluate the efficacy, safety, and immunogenicity of a SARS-CoV-2 mRNA vaccine (Omicron BA.5) LVRNA012 given as the booster in immunized but SARS-CoV-2 infection-free adults in China. Methods: This is a single-center, randomized, double-blind, placebo-controlled phase 3 clinical trial enrolling healthy adult participants (≥18 years) who had completed two or three doses of inactivated COVID-19 vaccines at least 6 months before, in Bengbu, Anhui province, China. Eligible participants were randomly assigned (1:1) to receive a booster intramuscular vaccination with an LVRNA012 vaccine (100ug) or placebo. The primary endpoint was the protective efficacy of a booster dose of the LVRNA012 vaccine or placebo against symptomatic COVID-19 of any severity 14 days after vaccination. Laboratory-confirmed COVID-19 infections were identified from 14 days to 180 days after intervention, with active surveillance for symptomatic illness 8 times per month between 7 to 90 days and at least once per month between 90 to 180 days after intervention. Results: 2615 participants were recruited and randomly assigned in a 1:1 ratio to either the vaccine group (1308) or the placebo group (1307). A total of 141 individuals (46 in the LVRNA012 group and 95 in the placebo group) developed symptomatic COVID-19 infection 14 days after the booster immunization, showing a vaccine efficacy of 51.9% (95% CI, 31.3% to 66.4%). Most infections were detected 90 days after intervention during a period when XBB was prevalent in the community. Adverse reactions were reported by 64% of participants after the LVRNA012 vaccination, but most of them were mild or moderate. The booster vaccination with the LVRNA012 mRNA vaccine could significantly enhance neutralizing antibody titers against the Omicron variant XBB.1.5 (GMT 132.3 [99.8, 175.4]) than did those in the placebo group (GMT 12.5 [8.4, 18.7]) at day 14 for the previously immunized individuals. Conclusion: The LVRNA012 mRNA vaccine is immunogenic, and shows robust efficacy in preventing COVID-19 during the omicron-predominate period. Clinical trial registration: ClinicalTrials.gov, identifier NCT05745545.
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Anticorpos Antivirais , Vacinas contra COVID-19 , COVID-19 , Imunização Secundária , Imunogenicidade da Vacina , SARS-CoV-2 , Humanos , Vacinas contra COVID-19/imunologia , Vacinas contra COVID-19/efeitos adversos , Vacinas contra COVID-19/administração & dosagem , Masculino , Feminino , COVID-19/prevenção & controle , COVID-19/imunologia , Adulto , Método Duplo-Cego , SARS-CoV-2/imunologia , Pessoa de Meia-Idade , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Vacinas de mRNA , Eficácia de Vacinas , Adulto Jovem , China , Anticorpos Neutralizantes/sangue , Anticorpos Neutralizantes/imunologia , Vacinas Sintéticas/imunologia , Vacinas Sintéticas/efeitos adversos , Vacinas Sintéticas/administração & dosagemRESUMO
Introduction: Respiratory infectious diseases, such as influenza and coronavirus disease 2019 (COVID-19), present significant global public health challenges. The emergence of artificial intelligence (AI) and big data offers opportunities to improve traditional disease surveillance and early warning systems. Methods: The study analyzed data from January 2020 to May 2023, comprising influenza-like illness (ILI) statistics, Baidu index, and clinical data from Weifang. Three methodologies were evaluated: the adaptive dynamic threshold method (ADTM) for dynamic threshold adjustments, the machine learning supervised method (MLSM), and the machine learning unsupervised method (MLUM) utilizing anomaly detection. The comparison focused on sensitivity, specificity, timeliness, and warning consistency. Results: ADTM issued 37 warnings with a sensitivity of 71% and a specificity of 85%. MLSM generated 35 warnings, with a sensitivity of 82% and a specificity of 87%. MLUM produced 63 warnings with a sensitivity of 100% and specificity of 80%. The initial warnings from ADTM and MLUM preceded those from MLSM by five days. The Kappa coefficient indicated moderate agreement between the methods, with values ranging from 0.52 to 0.62 (P<0.05). Discussion: The study explores the comparison between traditional methods and two machine learning approaches for early warning systems. It emphasizes the validation of machine learning's reliability and underscores the unique advantages of each method. Furthermore, it stresses the significance of integrating machine learning models with various data sources to enhance public health preparedness and response, alongside acknowledging limitations and the need for broader validation.
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Amphibian skin is an abundant repository of bioactive peptides, important components of the defensive system. The variability of the bioactive peptide repertoires of individual species remains unclear. In this study, dark-spotted frogs were collected from Kunming in Yunnan Province, China and Guiyang in Guizhou Province, China to determine whether the bioactive peptides in amphibian skin differ between the two regions. Eight antimicrobial peptides and an antioxidant peptide were identified by screening of cDNA library. Among the identified peptides, three antimicrobial peptides (pelophylaxin-2GY, temporin-1GY, and temporin-1KM) and an antioxidant peptide (antioxidin-PN) are reported here for the first time. Nigrocin-1, nigrocin-2, and pelophylaxin-2 were expressed by frogs in both regions. Pelophylaxin-2GY and temporin-1GY were found only in the frogs from Guiyang, whereas antioxidin-PN, esculetin-1, esculetin-2, and temporin-1KM were found only in those from Kunming. This difference was confirmed by allele-specific RT-PCR. The bioactive peptides expressed clearly varied between these populations of the same species.
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Proteínas de Anfíbios/genética , Anti-Infecciosos/metabolismo , Antioxidantes/metabolismo , Anuros/genética , Geografia , Peptídeos/genética , Transcriptoma , Sequência de Aminoácidos , Proteínas de Anfíbios/química , Proteínas de Anfíbios/farmacologia , Animais , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Antioxidantes/química , Antioxidantes/farmacologia , Humanos , Dados de Sequência Molecular , Peptídeos/química , Peptídeos/farmacologiaRESUMO
The present study aims to use Ankistrodesmus sp. EHY to develop a viable and economic lipid production strategy using recycling of harvested microalgal effluent. In comparison to the control, the highest lipid content (52.4 %) and productivity (250.72 mg L-1 d-1) were achieved when 40 % recycled medium was used. Consistent with the trend of lipid accumulation, the six key lipogenetic genes were upregulated, as well as reactive oxygen species (ROS), glutathione (GSH) and genes encoding antioxidant enzymes during cultivation in recycled medium. Moreover, the consumption of dissolved organic carbon (DOC) and the increased humic acid (HA) in the recycled medium might also be associated with lipid biosynthesis. The biodiesel parameters of alga biomass-derived lipids were fitted to the standard of commercial biodiesel. In conclusion, this study offers an economically viable strategy for microalgal biofuel production and wastewater treatment using recycling of harvested microalgal effluent.
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Clorofíceas , Microalgas , Biocombustíveis , Lipídeos , BiomassaRESUMO
Recycled medium plus cadmium is a promising technique for reducing the cultivation cost and enhancing the yield of microalgae lipids. However, oxidative stress and cadmium toxicity significantly hinder the resulting photosynthetic efficiency, cell growth and cell activity. Herein, selenium nanoparticles (SeNPs) were used to increase the total biomass, biolipid productivity, and tolerance to cadmium. Wide-ranging analyses of photosynthesis, energy yield, fatty acid profiles, cellular ultrastructure, and oxidative stress biomarkers were conducted to examine the function of SeNPs in CO2 fixation and cadmium resistance in Ankistrodesmus sp. EHY. The application of 15 µM cadmium and 2 mg L-1 SeNPs further enhanced the algal biomass productivity and lipid productivity to 500.64 mg L-1 d-1 and 301.14 mg L-1 d-1, respectively. Moreover, the rates of CO2 fixation, chlorophyll synthesis and total nitrogen removal were similarly increased by the application of SeNPs. Exogenous SeNPs strengthened cell growth and cadmium tolerance by upregulating photosynthesis, the TCA cycle and the antioxidant system, reducing the uptake and translocation of cadmium, and decreasing the levels of reactive oxidative stress (ROS), extracellular polymeric substances (EPSs) and cellular Cd2+ level in EHY under recycled medium and cadmium stress conditions. Additionally, a maximum energy yield of 127.40 KJ L-1 and a lipid content of 60.15% were achieved in the presence of both SeNPs and cadmium stress. This study may inspire the efficient disposal of recycled medium and biolipid production while also filling the knowledge gaps regarding the mechanisms of SeNP functions in carbon fixation and cadmium tolerance in microalgae.
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This paper aims to explore the role of proline (Pro) in the production of biomass and astaxanthin (AST) in stress-induced Haematococcus pluvialis. The astaxanthin content and productivity were 24.02 mg g-1 and 2.22 mg/L d-1 under abiotic stresses, respectively. After 100 µM Pro supplementation, the biomass, AST and lipid contents reached 1.43 g/L, 29.91 mg g-1 and 56.79 %, which were enhanced by 19.16 %, 33.52 % and 11.08 %, respectively, compared to the control. Pro-treated regulated chlorophyll, carbohydrate and protein accumulation and upregulated carotenogenic, lipogenic and antioxidant enzymes-associated gene levels; as well as increased endogenous Pro content, but reduced ROS (Reactive oxygen species) and MDA (Malondialdehyde) levels and alleviated oxidative stress, which might be involved in AST biosynthesis. Further data showed Pro has a positive role in biomass and AST coaccumulation in different H. pluvialis species, suggesting application of Pro was an effective strategy to improve AST productivity of H. pluvialis.
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Clorofíceas , Clorófitas , Clorófitas/metabolismo , Clorofíceas/metabolismo , Xantofilas/metabolismo , Clorofila/metabolismoRESUMO
The regulation of tumor immunosuppressive microenvironments via precise drug delivery is a promising strategy for preventing tumor recurrence and metastasis. Inspired by the stealth strategy, a stealthy nanovehicle based on neutrophil camouflage is developed to achieve precise delivery and tumor immunotherapy by triggering pyroptosis. The nanovehicle comprises anti-CD11b- and IR820-conjugated bovine serum albumin nanoparticles loaded with decitabine. Camouflaged by neutrophils, the nanovehicles achieve efficient tumor delivery by neutrophil hitchhiking owing to the biotropism of neutrophils for tumors. The fluorescent signal molecule, IR820, on the nanovehicle acts as a navigation monitor to track the precise delivery of the nanovehicle. The released decitabine upregulates gasdermin E, and laser irradiation activates caspase-3, thereby resulting in pyroptosis, which improves the system's adaptive immune response. In a triple-negative breast cancer animal model, it regulates the immunosuppressive microenvironment for effective tumor immunotherapy and induces a long-lasting and strong immune memory to prevent lung metastasis.
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Neutrófilos , Piroptose , Animais , Decitabina , Recidiva Local de Neoplasia , Imunoterapia , Microambiente TumoralRESUMO
Amorphophallus konjac, belonging to the genus Amorphophallus of the Araceae family, is an economically important crop widely used in health products and biomaterials. In the present work, we performed the whole-genome assembly of A. konjac based on the NovaSeq platform sequence data. The final genome assembly was 4.58 Gb with a scaffold N50 of 3212 bp. The genome includes 39,421 protein-coding genes, and 71.75% of the assemblies were repetitive sequences. Comparative genomic analysis showed 1647 gene families have expanded and 2685 contracted in the A. konjac genome. Likewise, genome evolution analysis indicated that A. konjac underwent whole-genome duplication, possibly contributing to the expansion of certain gene families. Furthermore, we identified many candidate genes involved in the tuber formation and development, cellulose and lignification synthesis. The genome of A. konjac obtained in this work provides a valuable resource for the further study of the genetics, genomics, and breeding of this economically important crop, as well as for evolutionary studies of Araceae family.
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Amorphophallus , Amorphophallus/genética , Melhoramento Vegetal , Sequências Repetitivas de Ácido Nucleico , Genoma de Planta , GenômicaRESUMO
BACKGROUND: COVID-19 caused by SARS-CoV-2 is a great threat to public health. We present the safety and immunogenicity data from a phase I trial in China of an mRNA vaccine (LVRNA009). METHODS: In the single-centre, double-blind, placebo-controlled and dose-escalation study, 72 healthy unvaccinated adults aged 18-59 years were randomized (3:1) to receive LVRNA009 with one of three vaccine dosage (25, 50 and 100 µg) or placebo, to evaluate for the safety, tolerability and immunogenicity of LVRNA009. RESULTS: All these participants received two injections 28 days apart. No adverse events higher than grade 2 were reported during the study. A total of 30 participants (42 %) reported solicited adverse reactions during the first 14 days after vaccinations. Of the events reported, fever (n = 11, 15 %) was the most common systemic adverse reaction, and pain at the injection site (n = 17, 24 %) was the most frequent solicited local adverse reaction. Anti-S-protein IgG and neutralising antibodies were observed to have been induced 14 days after the first dose, significantly increased 7 days after the second dose, and remained at a high level 28 days after the second dose. Specific T-cell responses peaked 7 days and persisted 28 days after second vaccination. CONCLUSION: LVRNA009 has demonstrated promising results in safety and tolerability at all three dose levels among Chinese adults. LVRNA009 at three dose levels could rapidly induce strong humoral and cellular immune responses, including binding and neutralising antibody production and IFN- γ secretion, which showed good immunogenicity. CLINICAL TRIAL REGISTRATION NUMBER: Clinicaltrials.gov NCT05364047; Chictr.org.cn ChiCTR2100049349.
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Vacinas contra COVID-19 , COVID-19 , Adulto , Humanos , Anticorpos Neutralizantes , Anticorpos Antivirais , COVID-19/prevenção & controle , Vacinas contra COVID-19/uso terapêutico , Método Duplo-Cego , População do Leste Asiático , Imunogenicidade da Vacina , SARS-CoV-2 , Vacinas de mRNARESUMO
Microalgae are highly adaptable to abiotic stress and produce valuable metabolites, but microalgal commercialization is still difficult because of minimal yields. The application of phytohormone-like small biomolecules is effective in simultaneously improving the productivity of valuable microalgal biomass-derived metabolites and stress tolerance. This represents a significant opportunity for microalgal biotechnology.
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Microalgas , Biocombustíveis , Biomassa , Biotecnologia , Microalgas/metabolismo , Reguladores de Crescimento de Plantas/metabolismoRESUMO
To obtain higher yield of natural astaxanthin, the present study aims to develop a viable and economic induction strategy for astaxanthin production comprising succinic acid (SA) combined with sodium hydrosulfide (NaHS). The biomass (1.33 g L-1), astaxanthin concentration (44.96 mg L-1), astaxanthin content (163.55 pg cell-1), and lipid content (55.34%) were achieved under 1.0 mM SA and 100 µM NaHS treatment. These results were concomitant with enhanced hydrogen sulfide (H2S) but diminished reactive oxide species (ROS). Further study discovered that endogenous H2S could improve astaxanthin and lipid coproduction under SA induction by mediating related gene transcript levels and ROS signalling. Additionally, the concentrations of biomass and astaxanthin increased to 2.14 g L-1 and 66.25 mg L-1, respectively, under the induction of SA and NaHS in a scaled-up bioreactor. Briefly, the work proposed a novel feasible strategy for high yields of biomass and astaxanthin by H. pluvialis.
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Clorofíceas , Sulfeto de Hidrogênio , Biomassa , Lipídeos , Espécies Reativas de Oxigênio , Ácido Succínico , XantofilasRESUMO
Induction of copper ion (Cu2+) stress is a method used to increase lipid accumulation in microalgae, but it decreases cell growth. In this work, the impacts of gamma-aminobutyric acid (GABA) coupled with Cu2+ stress on the biomass and oil yield in Monoraphidium sp. QLY-1 were investigated. Results suggested that the combined treatment of GABA and Cu2+ resulted in a higher lipid content (55.13%) than Cu2+ treatment (48.43%). Furthermore, GABA addition upregulated the levels of lipid-relevant genes, cellular GABA, ethylene (ETH), and antioxidant enzyme activities and alleviated oxidative damage caused by Cu2+ stress. The autophagy-relevant gene atg8 was also upregulated by GABA treatment. Further exploration indicated that cell autophagy induced the lipid content up to 58.09% with GABA and Cu2+ stress treatment. This investigation demonstrates that the coupling strategy can stimulate lipid production and shed light on the underlying mechanisms in lipid biosynthesis, cell autophagy, and stress response of microalgae.
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Clorofíceas , Microalgas , Cobre/farmacologia , Lipídeos , Ácido gama-Aminobutírico/farmacologiaRESUMO
A major challenge facing by astaxanthin industrialization is the low productivity and high production costs. This study established a two-stage cultivation strategy based on the application of NaCl to improve the production of biomass and astaxanthin by Haematococcus pluvialis. During the first growth stage, 12.5 mg L-1 NaCl led to a remarkable enhancement in biomass, which was 1.28 times compared with the control. Moreover, 2 g L-1 NaCl stimulated the astaxanthin content from 12.18 mg g-1 to 25.92 mg g-1 during the second induction stage. Simultaneously, salinity stress application increased the lipids and GABA contents, as well as the levels of Ca2+ and carotenogenic genes' expression, but suppressed the contents of carbohydrate and protein and high-light induced-ROS. This study proposed a simple and convenient strategy for efficient coproduction of biomass and astaxanthin and provides insights into the underlying mechanism of astaxanthin biosynthesis in H. pluvialis induced by salinity stress.