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1.
J Glob Antimicrob Resist ; 20: 160-162, 2019 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-31877398

RESUMO

OBJECTIVES: Recently, the Gram-negative bacterium Klebsiella oxytoca has been identified as an emerging pathogen. Here we report the draft genome of a 2,3-butanediol-producing strain, K. oxytoca CCTCC M207023, isolated from soil in Nanjing, China. The tetracycline-resistant phenotype and the high yield of 2,3-butanediol was demonstrated. METHODS: The draft genome of K. oxytoca CCTCC M207023 was determined using an Illumina NovaSeq™ 6000 next-generation DNA sequencing platform. Clean sequencing data were subsequently assembled using SOAPdenovo. RESULTS: The draft genome of K. oxytoca CCTCC M207023, comprising 5 658 144bp and with a GC content of 56.50%, was assembled into 5262 open-reading frames (ORFs). Antimicrobial resistance genes were also annotated. CONCLUSIONS: The draft genome sequence of K. oxytoca CCTCC M207023 reported here will be a reference for comparative analysis with the antimicrobial resistance mechanisms for the safety of 2,3-butanediol industrial production.

2.
Acta Otolaryngol ; 139(11): 939-947, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31486693

RESUMO

Background: Inner gene therapy offers great promises as a potential treatment for hearing loss. Aims/objectives: One of the critical determinants of the success of inner ear gene therapy is to find a delivery method which results in consistent transduction efficiency of targeted cell types while minimizing hearing loss. Material and methods: Surgery was performed only in the right ear of each Bama miniature pig, and the left ear served as a control. The gene delivery to inner ear via round window membrane (RWM) and posterior semicircular canal (PSC) approach was performed with the viral vector AAV1-CMV-GFP. Results: The gene delivery through RWM and the PSC (canalostomy) is able to perfuse the inner ear. Conclusions and significance: The easy anatomic identification of the PSC, as to RWM, as well as minimal manipulation of the temporal bone required, make this surgical approach an attractive option for inner ear gene delivery in big animal model.

3.
J Agric Food Chem ; 67(35): 9851-9857, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31418561

RESUMO

Arachidonic acid (ARA, C20:4) is a typical ω-6 polyunsaturated fatty acid with special functions. Using Yarrowia lipolytica as an unconventional chassis, we previously showed the performance of the Δ-6 pathway in ARA production. However, a significant increase in the Δ-9 pathway has rarely been reported. Herein, the Δ-9 pathway from Isochrysis galbana was constructed via pathway engineering, allowing us to synthesize ARA at 91.5 mg L-1. To further improve the ARA titer, novel enzyme fusions of Δ-9 elongase and Δ-8 desaturase were redesigned in special combinations containing different linkers. Finally, with the integrated pathway engineering and synthetic enzyme fusion, a 29% increase in the ARA titer, up to 118.1 mg/L, was achieved using the reconstructed strain RH-4 that harbors the rigid linker (GGGGS). The results show that the combined pathway and protein engineering can significantly facilitate applications of Y. lipolytica.


Assuntos
Ácido Araquidônico/biossíntese , Engenharia Metabólica , Yarrowia/genética , Yarrowia/metabolismo , Acetiltransferases/genética , Acetiltransferases/metabolismo , Ácidos Graxos Dessaturases/genética , Ácidos Graxos Dessaturases/metabolismo , Glucose/metabolismo , Haptófitas/enzimologia
4.
Appl Microbiol Biotechnol ; 103(11): 4313-4324, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31016357

RESUMO

In recent years, eukaryotic microorganisms have been widely applied to offer many solutions for everyday life and have come to play important roles in agriculture, food, health care, and the fine-chemicals industry. However, the complex genetic background and low homologous recombination efficiency have hampered the implementation of large-scale and high-throughput gene editing in many eukaryotic microorganisms. The low efficiency of homologous recombination (HR) not only makes the modification process labor-intensive but also completely precludes the application of many otherwise very useful genome editing techniques. Thus, increasing the efficiency of HR is clearly an enabling technology for basic research and gene editing in eukaryotic microorganisms. In this review, we summarize the current strategies for enhancing the efficiency of HR in eukaryotic microorganisms (particularly yeasts and filamentous fungi), list some small molecules and candidate genes associated with homologous and non-homologous recombination, and briefly discuss the further development prospects of these strategies.


Assuntos
Fungos/genética , Edição de Genes/métodos , Recombinação Homóloga , Engenharia Metabólica/métodos , Leveduras/genética
5.
Bioresour Technol ; 281: 449-456, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30846235

RESUMO

Terpenoids are a large class of natural compounds based on the C5 isoprene unit, with many biological effects such activity against cancer and allergies, while some also have an agreeable aroma. Consequently, they have received extensive attention in the food, pharmaceutical and cosmetic fields. With the identification and analysis of the underlying natural product synthesis pathways, current microbial-based metabolic engineering approaches have yielded new strategies for the production of highly valuable terpenoids. Yarrowia lipolytica is a non-conventional oleaginous yeast that is rapidly emerging as a valuable host for the production of terpenoids due to its own endogenous mevalonate pathway and high oil production capacity. This review aims to summarize the status and strategies of metabolic engineering for the heterologous synthesis of terpenoids in Y. lipolytica in recent years and proposes new methods aiming towards further improvement of terpenoid production.


Assuntos
Engenharia Metabólica/métodos , Terpenos/metabolismo , Yarrowia/metabolismo , Produtos Biológicos/metabolismo
6.
ACS Synth Biol ; 8(2): 445-454, 2019 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-30616338

RESUMO

The filamentous fungus Fusarium fujikuroi is well-known for its production of natural plant growth hormones: a series of gibberellic acids (GAs). Some GAs, including GA1, GA3, GA4, and GA7, are biologically active and have been widely applied in agriculture. However, the low efficiency of traditional genetic tools limits the further research toward making this fungus more efficient and able to produce tailor-made GAs. Here, we established an efficient CRISPR/Cas9-based genome editing tool for F. fujikuroi. First, we compared three different nuclear localization signals (NLS) and selected an efficient NLS from histone H2B (HTBNLS) to enable the import of the Cas9 protein into the fungal nucleus. Then, different sgRNA expression strategies, both in vitro and different promoter-based in vivo strategies, were explored. The promoters of the U6 small nuclear RNA and 5S rRNA, which were identified in F. fujikuroi, had the highest editing efficiency. The 5S rRNA-promoter-driven genome editing efficiency reached up to 79.2%. What's more, multigene editing was also explored and showed good results. Finally, we used the developed genome editing tool to engineer the metabolic pathways responsible for the accumulation of a series GAs in the filamentous fungus F. fujikuroi, and successfully changed its GA product profile, from GA3 to tailor-made GA4 and GA7 mixtures. Since these mixtures are more efficient for agricultural use, especially for fruit growth, the developed strains will greatly improve industrial GA production.


Assuntos
Sistemas CRISPR-Cas/genética , Fungos/genética , Fungos/metabolismo , Fusarium/genética , Fusarium/metabolismo , Giberelinas/metabolismo , Edição de Genes/métodos , Genoma Fúngico/genética
7.
Bioresour Technol ; 271: 118-124, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30265951

RESUMO

The aim of this work was to reduce the algae-residue emission and make use of cane molasses as fermentation materials for docosahexaenoic acid (DHA) fermentaion by Schizochytrium sp., which further could cut the cost of DHA production. Algae-residue and cane molasses were respectively used as nitrogen and carbon sources to replace yeast extract and glucose. A significant DHA yield of 18.58 g/L was obtained using algae-residue, while cane molasses could not be used well as sole carbon source due to the presence of undesirable substance. A two-stage culture strategy with glucose followed by pretreated cane molasses as carbon source was developed, resulting in a final DHA yield of 15.22 g/L. This study therefore offers an economical and green strategy for DHA production by Schizochytrium sp.


Assuntos
Bengala , Ácidos Docosa-Hexaenoicos/biossíntese , Estramenópilas/metabolismo , Carbono/metabolismo , Fermentação , Glucose/metabolismo , Melaço , Nitrogênio/metabolismo
8.
Biochim Biophys Acta Mol Cell Biol Lipids ; 1864(4): 552-566, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30308323

RESUMO

Microalgal lipids have drawn great attention as a promising sustainable resource for biodiesel or food supplement production. The development of high-performance strains of microalgae by metabolic engineering is invaluable for increasing the quantity or quality of desired lipids. The synthesis routes of lipids used as biodiesel in microalgae are based on fatty acid synthase (FAS) and triacylglycerols (TAG) biosynthesis pathway. Polyunsaturated fatty acids (PUFAs), including ω-6 and ω-3 fatty acids, are essential nutrients for humans. Notably, microalgae possess two distinct pathways for polyunsaturated fatty acids (PUFAs) biosynthesis, including the desaturase/elongase pathway and the polyketide synthase (PKS) pathway. Thus, it is necessary to identify which biosynthetic pathways are responsible for PUFA synthesis in particular microalgae species. In recent years, various key enzymes and functional domains involved in fatty acid and TAG biosynthesis pathway were identified and potentially regulated by genetic engineering approaches to elevate specific lipids content. In addition, other studies have reported the implementation of strategies to increase lipid accumulation based on increasing acetyl-CoA/NADPH supply, enhancing photosynthetic efficiency, or blocking competing pathways. Furthermore, other efforts have used transcription factor engineering to simultaneously regulate multiple genes related to lipid accumulation. This review summarizes recent research about a variety of microalgae lipid biosynthesis pathways, and discusses multiple gene manipulation strategies that have been employed for specific lipid overproduction in industrial microalgae.


Assuntos
Ácidos Graxos Insaturados/biossíntese , Engenharia Metabólica/métodos , Microalgas/crescimento & desenvolvimento , Engenharia Genética , Metabolismo dos Lipídeos , Microalgas/genética , Microalgas/metabolismo , Fotossíntese , Policetídeo Sintases
9.
J Invest Surg ; 32(8): 689-696, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29693474

RESUMO

Objective: The objectives of this study were to examine the clinical profile of critically ill patients with septic acute kidney injury (AKI) and to investigate clinical characteristics associated with the outcome of patients. Methods: Data from 582 critically ill patients were collected and retrospectively reviewed. Patients were divided into two groups: without AKI development and with AKI development. Baseline characteristics, laboratory, and other clinical data were compared between these two groups, and correlations between the characteristics and AKI development were examined. Patients with AKI development were further divided into two groups according to the survival outcome, and variables associated with the outcome were determined. Results: AKI was developed in 54.12% (n = 315) of patients, and these patients had blood pressure, SOFA score, APACHE II score, GCS, and various blood chemistry and hematology characteristics significantly different from the patients without AKI. Demographic characteristics (e.g. age and weight) were comparable between the two groups of patients. Among the 315 patients with AKI, 136 of them died during the study period. Multivariate logistic regression analysis revealed that the outcome of patients was associated with lung infection, coagulation system dysfunction, staphylococcus aureus infection, and use of various treatments (epinephrine, norepinephrine, and the use of mechanical ventilation) after AKI development. Conclusion: AKI occurred in approximately half of the critically ill patients admitted to ICU. The site and type of infections, as well as the use of vasopressor agents, were associated with the outcome.

10.
Trends Biotechnol ; 37(4): 344-346, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30376959

RESUMO

Polyunsaturated fatty acids (PUFAs) are important for human health. They are traditionally extracted from animals and plants but can be alternatively derived from oleaginous microbes, and engineering microbial metabolism can improve PUFA accumulation. The next frontier is to engineer more efficient PUFA-producing microbes using systems and synthetic biology tools.


Assuntos
Ácidos Graxos Insaturados/biossíntese , Fungos/genética , Fungos/metabolismo , Engenharia Metabólica/métodos , Redes e Vias Metabólicas/genética , Estramenópilas/genética , Estramenópilas/metabolismo , Biotecnologia/métodos , Ácidos Graxos Insaturados/isolamento & purificação , Humanos
11.
Front Microbiol ; 9: 2788, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30519220

RESUMO

The production of pneumocandin B0 is limited by feedback inhibition. Here, low-temperature adaptive laboratory evolution (ALE) was used to improve the production capacity of Glarea lozoyensis by enhancing its membrane permeability. After 50 cycles of ALE, the pneumocandin B0 production of the endpoint strain (ALE50) reached 2131 g/L, which was 32% higher than the starting strain (ALE0). ALE50 showed a changed fatty acid composition of the cell membrane, which-+h increased its permeability by 14%, which in turn increased the secretion ratio threefold. Furthermore, ALE50 showed increased intracellular proline and acetyl-CoA concentrations, superoxide dismutase (SOD), and catalase (CAT) activity, as well as total antioxidant capacity. The slight biomass decrease in ALE50 was accompanied by decreased isocitrate dehydrogenase (ICDH) and glucose-6-phosphate dehydrogenase (G6PDH) activity. Finally, a putative model of the accumulation and secretion of pneumocandin B0 in ALE50 was established. ALE is a promising method to release intracellular feedback inhibition.

12.
Front Microbiol ; 9: 2185, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30298059

RESUMO

The beta-hydroxy acid 3-hydroxypropionic acid (3-HP) is an attractive platform compound that can be used as a precursor for many commercially interesting compounds. In order to reduce the dependence on petroleum and follow sustainable development, 3-HP has been produced biologically from glucose or glycerol. It is reported that 3-HP synthesis pathways can be constructed in microbes such as Escherichia coli, Klebsiella pneumoniae and the yeast Saccharomyces cerevisiae. Among these host strains, yeast is prominent because of its strong acid tolerance which can simplify the fermentation process. Currently, the malonyl-CoA reductase pathway and the ß-alanine pathway have been successfully constructed in yeast. This review presents the current developments in 3-HP production using yeast as an industrial host. By combining genome-scale engineering tools, malonyl-CoA biosensors and optimization of downstream fermentation, the production of 3-HP in yeast has the potential to reach or even exceed the yield of chemical production in the future.

13.
Biotechnol Biofuels ; 11: 272, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30305845

RESUMO

Microalgae have drawn great attention as promising sustainable source of lipids and carotenoids. Their lipid and carotenoids accumulation machinery can be trigged by the stress conditions such as nutrient limitation or exposure to the damaging physical factors. However, stressful conditions often adversely affect microalgal growth and cause oxidative damage to the cells, which can eventually reduce the yield of the desired products. To overcome these limitations, two-stage cultivation strategies and supplementation of growth-promoting agents have traditionally been utilized, but developing new highly adapted strains is theoretically the simplest strategy. In addition to genetic engineering, adaptive laboratory evolution (ALE) is frequently used to develop beneficial phenotypes in industrial microorganisms during long-term selection under specific stress conditions. In recent years, many studies have gradually introduced ALE as a powerful tool to improve the biological properties of microalgae, especially for improving the production of lipid and carotenoids. In this review, strategies for the manipulation of stress in microalgal lipids and carotenoids production are summarized and discussed. Furthermore, this review summarizes the overall state of ALE technology, including available selection pressures, methods, and their applications in microalgae for the improved production of lipids and carotenoids.

14.
Front Microbiol ; 9: 2352, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30364147

RESUMO

Pneumocandin B0 is an important antifungal drug precursor produced by filamentous fungus Glarea lozoyensis. The high broth viscosity of cultures of this organism results in lower oxygen solubility and higher energy consumption for agitation and aeration, which mostly caused by the morphologies of filamentous fungi in submerged culture. In this study, the effects of different seed medium nitrogen sources on morphology and fermentation behavior of G. lozoyensis were investigated, and cotton seed powder resulted in small, compact pellets. Moreover, pneumocandin B0 yield in Erlenmeyer flasks were increased by 22.9%. Furthermore, pneumocandin B0 yield in a 50-L fermenter reached 2,100 mg/L and the dissolved oxygen maintained above 30%. Additionally, activities of phosphofructokinase (PFK), isocitrate dehydrogenase (ICDH), glucose 6-phosphate dehydrogenase (G6PDH), and malic enzyme (ME) were increased by 87.5, 50, 41.6, and 10.7%, respectively. This study demonstrates the feasibility and advantages of using cotton seed powder for controlling the fungal morphology and improving the product yield in pneumocandin fermentations.

15.
Biotechnol Biofuels ; 11: 249, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30245741

RESUMO

Background: Schizochytrium sp. is a promising strain for the production of docosahexaenoic acid (DHA)-rich oil and biodiesel, and has been widely used in the food additive and bioenergy industries. Oxygen is a particularly important environmental factor for cell growth and DHA synthesis. In general, higher oxygen supply favors lipid accumulation, but could lead to a reduction of the DHA percentage in total fatty acids in Schizochytrium sp. To tackle this problem, it is essential to understand the mechanisms regulating the response of Schizochytrium sp. to oxygen. In this study, we aimed to explore the acclimatization of this DHA producer to different oxygen supply conditions by examining the transcriptome changes. Results: Two different fermentation processes, namely normal oxygen supply condition (shift agitation speeds from 400 rpm to 300 rpm) and high oxygen supply condition (constant agitation speeds: 400 rpm), were designed to study how the fermentation characteristics of Schizochytrium sp. HX-308 were affected by different oxygen supply conditions. The results indicated that high oxygen supply condition resulted in 49% and 37.5% improvement in the maximum cell dry weight (CDW) and total lipid concentration, respectively. However, the DHA percentage in total fatty acids decreased to 35%, which was 31.4% lower than that produced by normal oxygen supply condition. Moreover, transcriptome analysis was performed to explore the effect of the oxygen supply condition on genetic expression and metabolism. The results showed that glycolysis and pentose phosphate pathway metabolism-associated genes (hexokinase, phosphofructokinase, fructose-bisphosphate aldolase, glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase) were substantially upregulated in response to high oxygen supply, resulting in more NADPH was available for Schizochytrium. Specially, high oxygen supply condition also led to genes (Δ6 desaturase, Δ12 desaturase, FAS, ORFA, ORFB, and ORFC) involved in fatty acid biosynthesis upregulation. In addition, a transcriptional upregulation of catalase (CAT) became apparent under high oxygen supply condition, while superoxide dismutase (SOD) and ascorbate peroxidase (APX) were found to be down-regulated. Conclusions: This study is the first to investigate the differences of gene expression at different levels of oxygen availability in the DHA producer Schizochytrium. The results of transcriptome analyses indicated that high oxygen supply condition resulting in more NADPH and acetyl-CoA production for cell growth and lipid synthesis in Schizochytrium. Δ12 desaturase and ORFC showed higher expression levels at high oxygen supply condition, which might be the key regulators for enhancing fatty acid biosynthesis in the future. These results enrich the current knowledge regarding genetic expression and provide important information to enhance DHA production in Schizochytrium sp.

16.
AMB Express ; 8(1): 150, 2018 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-30242564

RESUMO

Enhancing lipid productivity and reducing oxidative damage is essential for lipid overproduction in microalgae. In this study, addition of 20 mg/L fulvic acid (FA) resulted a 34.4% increase of lipid yield in Schizochytrium sp. Furthermore, the cooperative effect of FA and EDTA on cell growth and lipid production was investigated. The combined addition of 20 mg/L FA and 1.0 g/L EDTA yielded a maximal cell dry weight of 130.7 g/L and lipid productivity of 1.16 g/L/h, representing 36.4% and threefold increase over the non-supplemented group, respectively. Moreover, compared with the non-supplemented group, the combined addition strategy exhibited overall lower levels of reactive oxygen species and malondialdehyde, which accompanied with 66.7% and 81.9% higher superoxide dismutase and catalase activity, respectively. Furthermore, a 24.1-37.1% increase of malic enzyme and 19.4-25.2% decrease of phosphoenolpyruvate carboxylase activity was observed during the entire fermentation stage (0-108 h). Results suggested that the combined addition strategy not only enhanced lipid accumulation, but also prevented the lipid peroxidation.

17.
Appl Microbiol Biotechnol ; 102(22): 9541-9548, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30238143

RESUMO

The oleaginous yeast Yarrowia lipolytica is widely used for the production of both bulk and fine chemicals, including organic acids, fatty acid-derived biofuels and chemicals, polyunsaturated fatty acids, single-cell proteins, terpenoids, and other valuable products. Consequently, it is becoming increasingly popular for metabolic engineering applications. Multiple gene manipulation tools including URA blast, Cre/LoxP, and transcription activator-like effector nucleases (TALENs) have been developed for metabolic engineering in Y. lipolytica. However, the low efficiency and time-consuming procedures involved in these methods hamper further research. The emergence of the CRISPR/Cas system offers a potential solution for these problems due to its high efficiency, ease of operation, and time savings, which can significantly accelerate the genomic engineering of Y. lipolytica. In this review, we summarize the research progress on the development of CRISPR/Cas systems for Y. lipolytica, including Cas9 proteins and sgRNA expression strategies, as well as gene knock-out/knock-in and repression/activation applications. Finally, the most promising and tantalizing future prospects in this area are highlighted.


Assuntos
Engenharia Metabólica/métodos , Yarrowia/genética , Yarrowia/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sistemas CRISPR-Cas , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Engenharia Metabólica/tendências
18.
Bioresour Technol ; 269: 32-39, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30149252

RESUMO

Docosahexaenoic acid (DHA) has wide-ranging benefits for normal development of the visual and nervous systems in infants. A sustainable source of DHA production through fermentation using Schizochytrium sp. has been developed. In this paper, we present the discovery of growth-uncoupled DHA production by Schizochytrium sp. and the development of corresponding kinetic models of fed-batch fermentations, which can be used to describe and predict the cell growth and substrate utilization as well as lipid and DHA production. Based on this kinetic model, a predictive model of multi-stage continuous fermentation process was established and used to analyze, optimize and design the process parameters. Optimal predicted processes of two-stage and three-stage continuous fermentation were developed and verified in lab-scale bioreactor based on the predicted process parameters. A successful three-stage continuous fermentation was achieved, which increased the lipid, DHA content and DHA productivity by 47.6, 64.3 and 97.1%, respectively, compared with two-stage continuous fermentation.


Assuntos
Ácidos Docosa-Hexaenoicos/metabolismo , Fermentação , Estramenópilas , Reatores Biológicos , Cinética
19.
Bioresour Technol ; 266: 482-487, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29990764

RESUMO

Fermentation wastewater (FW) and algal residue are major by-products of docosahexaenoic acid (DHA) fermentations utilizing Schizochytrium sp. In order to reduce production costs and environmental pollution, we explored the application of FW and algal-residue extract (AE) for DHA production. Components analysis showed that FW and AE contained some mineral elements and protein residues, respectively. When they were used for DHA fermentation, results showed that 20% replacement of fresh water by FW and 80% replacement of yeast extract nitrogen by AE reached DHA content of 22.23 g/L and 27.10 g/L, respectively. Furthermore, a novel medium that utilizes a mixture of FW and AE was applied for DHA fermentation, whereby the final DHA yield reached 28.45 g/L, 24.56% higher than conventional medium. The strategy of valorizing fermentation waste provides a new method for reducing the costs and reducing environmental pollution of microbial fermentations.


Assuntos
Ácidos Docosa-Hexaenoicos/metabolismo , Estramenópilas , Águas Residuárias , Fermentação , Nitrogênio
20.
Bioresour Technol ; 267: 438-444, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30032058

RESUMO

Lipid accumulation of Schizochytrium sp. can be induced by stress condition, but this stress-induction usually reduce cell growth and cause oxidative damage, which can eventually lower the lipid yield. Here, adaptive laboratory evolution (ALE) combined high salinity was performed to enhance the antioxidant system and lipid accumulation. The final strain ALE150, which was obtained after 150 days, showed a maximal cell dry weight (CDW) of 134.5 g/L and lipid yield of 80.14 g/L, representing a 32.7 and 53.31% increase over the starting strain, respectively. Moreover, ALE150 exhibited an overall higher total antioxidant capacity (T-AOC) and lower reactive oxygen species (ROS) levels than the starting strain. Furthermore, the regulatory mechanisms responsible for the improved performance of ALE150 were analyzed by transcriptomic analysis. Genes related to the antioxidant enzymes and central carbon metabolism were up-regulation. Moreover, the metabolic fluxes towards the fatty acid synthase (FAS) and polyketide synthase (PKS) pathways were also changed.


Assuntos
Lipídeos/biossíntese , Microalgas , Salinidade , Oxirredução , Estresse Oxidativo
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