Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 36
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Sheng Wu Gong Cheng Xue Bao ; 40(3): 665-686, 2024 Mar 25.
Artigo em Chinês | MEDLINE | ID: mdl-38545970

RESUMO

Erythritol is a novel 4-carbon sugar alcohol produced by microbes in the presence of hyper-osmotic stress. It has excellent potential to serve as an alternative sugar for people with diabetes and also a platform compound for synthesizing various C4 compounds, such as 1, 3-butadiene, 1, 4-butanediol, 2, 5-dihydrofuran and so on. Compared with other polyols, the fermentative production of erythritol is more challenging. Yarrowia lipolytica is the preferred chassis of erythritol biosynthesis for its high-titer and high-productivity. At present, there are still some bottlenecks in the production of erythritol by Y. lipolytica, such as weak metabolic activity, abundant by-products, and low industrial attributes. Progress has been made in tailoring high version strains according to industrial needs. For example, the highest titer of erythritol produced by the metabolically engineered Y. lipolytica reached 196 g/L and 150 g/L, respectively, by using glucose or glycerol as the carbon sources. However, further improving its production performance becomes challenging. This review summarizes the research progress in the synthesis of erythritol by Y. lipolytica from the perspectives of erythritol producing strains, metabolic pathways, modular modifications, and auxiliary strategies to enhance the industrial properties of the engineered strain. Key nodes in the metabolic pathway and their combination strategies are discussed to guide the research on promoting the production of erythritol by Y. lipolytica.


Assuntos
Yarrowia , Humanos , Yarrowia/genética , Yarrowia/metabolismo , Eritritol/metabolismo , Engenharia Metabólica , Fermentação , Carbono/metabolismo
2.
3 Biotech ; 14(4): 117, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38524241

RESUMO

D-Pantothenic acid, as a momentous vitamin, is extensively applied to feed, medicine, cosmetics and other fields. However, there are still limitations to produce D-pantothenic acid by microbial fermentation at present. In this paper, we constructed a recombinant strain for D-pantothenic acid production by blocking the organic acid pathway, boosting pyruvate biosynthesis, relieving feedback inhibition of acetolactate synthase, improving glucose intake capacity, and modifying essential genes in the metabolic pathway. In addition, a new acetolactate isomeroreductase mutant V412A origin from Escherichia coli (EcAHAIR) encoded by ilvC was obtained to explore its substrate promiscuity. Compared with the wild type, the variant EcAHAIR-V412A has reduced steric hindrance and enhanced intermolecular forces, resulting in a high affinity for 2-acetolactate. Eventually, the fermentation production of the final strain DPAN19/trc-ilvCV412A reached 4.65 g/L, increased by 192.5% compared with strain DPA8 in shake flask cultivation and produced 62.82 g/L D-pantothenic acid in a 5 L bioreactor. The metabolic engineering strategies and enzyme modification approaches described in this paper provide a particular perspective for the bio-manufacturing of D-pantothenic acid, branched-chain amino acids and its derivates.

3.
J Sci Food Agric ; 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38427028

RESUMO

BACKGROUND: One of the greatest challenges in using Lactobacillus acidophilus as a probiotic is acid stress. The current research aimed to identify substances that help L. acidophilus resist acid stress; this was achieved through assessing its nutrient consumption patterns under various pH conditions. RESULTS: The consumption rates of alanine, uracil, adenine, guanine, niacin, and manganese were consistently higher than 60% for L. acidophilus LA-5 cultured at pH 5.8, 4.9, and 4.4. The consumption rates of glutamic acid + glutamine and thiamine increased with decreasing pH and were higher than 60% at pH 4.9 and 4.4. The viable counts of L. acidophilus LA-5 were significantly increased under the corresponding acidic stress conditions (pH 4.9 and 4.4) through the appropriate addition of either alanine (3.37 and 2.81 mmol L-1 ), glutamic acid + glutamine (4.77 mmol L-1 ), guanine (0.13 and 0.17 mmol L-1 ), niacin (0.02 mmol L-1 ), thiamine (0.009 mmol L-1 ), or manganese (0.73 and 0.64 mmol L-1 ) (P < 0.05). The viable counts of L. acidophilus LA-5 cultured in a medium supplemented with combined nutritional factors was 1.02-1.03-fold of the counts observed in control medium under all acid conditions (P < 0.05). CONCLUSION: Alanine, glutamic acid + glutamine, guanine, niacin, thiamine, and manganese can improve the growth of L. acidophilus LA-5 in an acidic environment in the present study. The results will contribute to optimizing strategies to enhance the acid resistance of L. acidophilus and expand its application in the fermentation industry. © 2024 Society of Chemical Industry.

4.
J Appl Microbiol ; 135(2)2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38299790

RESUMO

AIMS: During fermentation, the accumulation of acidic products can induce media acidification, which restrains the growth of Bifidobacterium animalis subsp. lactis Bb12 (Bb12). This study investigated the nutrient consumption patterns of Bb12 under acid stress and effects of specific nutrients on the acid resistance of Bb12. METHODS AND RESULTS: Bb12 was cultured in chemically defined medium (CDM) at different initial pH values. Nutrient consumption patterns were analyzed in CDM at pH 5.3, 5.7, and 6.7. The patterns varied with pH: Asp + Asn had the highest consumption rate at pH 5.3 and 5.7, while Ala was predominant at pH 6.7. Regardless of the pH levels (5.3, 5.7, or 6.7), ascorbic acid, adenine, and Fe2+ were vitamins, nucleobases, and metal ions with the highest consumption rates, respectively. Nutrients whose consumption rates exceeded 50% were added individually in CDM at pH 5.3, 5.7, and 6.7. It was demonstrated that only some of them could promote the growth of Bb12. Mixed nutrients that could promote the growth of Bb12 were added to three different CDM. In CDM at pH 5.3, 5.7, and 6.7, it was found that the viable cell count of Bb12 was the highest after adding mixed nutrients, which were 8.87, 9.02, and 9.10 log CFU ml-1, respectively. CONCLUSIONS: The findings suggest that the initial pH of the culture medium affects the nutrient consumption patterns of Bb12. Specific nutrients can enhance the growth of Bb12 under acidic conditions and increase its acid resistance.


Assuntos
Bifidobacterium animalis , Probióticos , Ácidos , Purinas , Nutrientes , Pirimidinas , Concentração de Íons de Hidrogênio
5.
Food Res Int ; 177: 113849, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38225124

RESUMO

The aim of this study was to investigate the dynamic profile of microorganisms and metabolites in Hainan Trinitario cocoa during a six-day spontaneous box fermentation process. Shotgun metagenomic and metabolomic approaches were employed for this investigation. The potential metabolic functions of microorganisms in cocoa fermentation were revealed through a joint analysis of microbes, functional genes, and metabolites. During the anaerobic fermentation phase, Hanseniaspora emerged as the most prevalent yeast genus, implicated in pectin decomposition and potentially involved in glycolysis and starch and sucrose metabolism. Tatumella, possessing potential for pyruvate kinase, and Fructobacillus with a preference for fructose, constituted the primary bacteria during the pre-turning fermentation stage. Upon the introduction of oxygen into the fermentation mass, acetic acid bacteria ascended to dominant within the microflora. The exponential proliferation of Acetobacter resulted in a decline in taxonomic richness and abundance. Moreover, the identification of novel species within the Komagataeibacter genus suggests that Hainan cocoa may serve as a valuable reservoir for the discovery of unique cocoa fermentation bacteria. The KEGG annotation of metabolites and enzymes also highlighted the significant involvement of phenylalanine metabolism in cocoa fermentation. This research will offer a new perspective for the selection of starter strains and the formulation of mixed starter cultures.


Assuntos
Cacau , Chocolate , Microbiota , Fermentação , Bactérias , Cacau/metabolismo
6.
Bioresour Technol ; 394: 130220, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38109979

RESUMO

Pseudomonas putida KT2440, a GRAS strain, has been used for synthesizing bulk and fine chemicals. However, the gene editing tool to metabolically engineer KT2440 showed low efficiency. In this study, a novel sacB-based system pK51mobsacB was established to improve the efficiency for marker-free gene disruption. Then the rhamnolipid synthetic pathway was introduced in KT2440 and genes of the competitive pathways were deleted to lower the metabolic burden based on pK51mobsacB. A series of endogenous and synthetic promoters were used for fine tuning rhlAB expression. The limited supply of dTDP-L-rhamnose was enhanced by heterologous rmlBDAC expression. Cell growth and rhamnolipid production were well balanced by using glucose/glycerol as mixed carbon sources. The final strain produced 3.64 g/L at shake-flask and 19.77 g/L rhamnolipid in a 5 L fermenter, the highest obtained among metabolically engineered KT2440, which implied the potential of KT2440 as a promising microbial cell factory for industrial rhamnolipid production.


Assuntos
Carbono , Pseudomonas putida , Carbono/metabolismo , Glicolipídeos/metabolismo , Regiões Promotoras Genéticas , Pseudomonas putida/genética , Pseudomonas putida/metabolismo
7.
Bioprocess Biosyst Eng ; 46(9): 1351-1363, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37468580

RESUMO

Erythritol is a novelty 4-carbon sugar polyol and has great potential to be used as the precursor of some platform chemicals. The increasing cost of glucose poses researchers shifting insights to the cheaper biodiesel raw materials. Herein, we engineered a non-degradation, non-byproducts Yarrowia lipolytica for the erythritol production with high-titer from glycerol. Initially, the degradation and competition modules were blocked by URA3 counter-selection marker. Subsequently, a shortened biosynthetic pathway was explored to elevate its synthetic flux by multi-modules combination expression of functional genes. Furthermore, a screened glycerol transporter ScFPS1 was integrated into ERY6 genome to promote the glycerol uptake. The constructed strain ERY8 produced 176.66 g/L erythritol in the 5-L bioreactor with a yield and productivity of 0.631 g/g and 1.23 g/L/h, respectively, which achieved the highest fermentation production efficiency till date. This study proposed a novel multi-modules combination strategy for effectively engineering Y. lipolytica to produce erythritol using glycerol.


Assuntos
Glicerol , Yarrowia , Glicerol/metabolismo , Yarrowia/genética , Yarrowia/metabolismo , Eritritol , Engenharia Metabólica , Reatores Biológicos
8.
Biotechnol Biofuels Bioprod ; 16(1): 8, 2023 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-36639820

RESUMO

BACKGROUND: (R)-mandelic acid (R-MA) is a highly valuable hydroxyl acid in the pharmaceutical industry. However, biosynthesis of optically pure R-MA remains significant challenges, including the lack of suitable catalysts and high toxicity to host strains. Adaptive laboratory evolution (ALE) was a promising and powerful strategy to obtain specially evolved strains. RESULTS: Herein, we report a new cell factory of the Gluconobacter oxydans to biocatalytic styrene oxide into R-MA by utilizing the G. oxydans endogenous efficiently incomplete oxidization and the epoxide hydrolase (SpEH) heterologous expressed in G. oxydans. With a new screened strong endogenous promoter P12780, the production of R-MA was improved to 10.26 g/L compared to 7.36 g/L of using Plac. As R-MA showed great inhibition for the reaction and toxicity to cell growth, adaptive laboratory evolution (ALE) strategy was introduced to improve the cellular R-MA tolerance. The adapted strain that can tolerate 6 g/L R-MA was isolated (named G. oxydans STA), while the wild-type strain cannot grow under this stress. The conversion rate was increased from 0.366 g/L/h of wild type to 0.703 g/L/h by the recombinant STA, and the final R-MA titer reached 14.06 g/L. Whole-genome sequencing revealed multiple gene-mutations in STA, in combination with transcriptome analysis under R-MA stress condition, we identified five critical genes that were associated with R-MA tolerance, among which AcrA overexpression could further improve R-MA titer to 15.70 g/L, the highest titer reported from bulk styrene oxide substrate. CONCLUSIONS: The microbial engineering with systematic combination of static regulation, ALE, and transcriptome analysis strategy provides valuable solutions for high-efficient chemical biosynthesis, and our evolved G. oxydans would be better to serve as a chassis cell for hydroxyl acid production.

9.
World J Microbiol Biotechnol ; 38(8): 131, 2022 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-35689127

RESUMO

The plant growth hormone gibberellic acid (GA3), as one of the representative secondary metabolites, is widely used in agriculture, horticulture and brewing industry. GA3 is detected in both plants and several fungi with the ability to stimulate plant growth. Currently, the main mode of industrial production of GA3 is depended on the microbial fermentation via long-period submerged fermentation using Fusarium fujikuroi as the only producing strain, qualified for its natural productivity. However, the demand of large-sale industrialization of GA3 was still restricted by the low productivity. The biosynthetic route of GA3 in F. fujikuroi is now well-defined. Furthermore, the multi-level regulation mechanisms involved in the whole network of GA3 production have also been gradually unveiled by the past two decades based on the identification and characterization of several global regulators and their mutual functions. Combined with the quick development of genetic manipulation techniques, the rational modification of producing strain F. fujikuroi development become practical for higher productivity achievement. Herein, we review the latest advances in the molecular regulation of GA3 biosynthesis in F. fujikuroi and conclude a comprehensive network involving nitrogen depression, global regulator, histone modification and G protein signaling pathway. Correspondingly, the bioengineering strategies covering conventional random mutation, genetic manipulating platform development, metabolic edition and fermentation optimization were also systematically proposed.


Assuntos
Fusarium , Giberelinas , Bioengenharia , Giberelinas/metabolismo , Reguladores de Crescimento de Plantas/metabolismo
10.
Bioresour Technol ; 352: 127024, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35337996

RESUMO

Biosynthesis of D-pantothenate has been widely studied as D-pantothenate is one kind of important vitamins used in food and pharmaceuticals. However, the engineered strain for D-pantothenate production was focused solely on the main biosynthetic pathway, while other important factors such as one carbon unit were ignored. Here the systematic modular engineering on different factors coupled with omics analysis were studied in Escherichia coli for efficient D-pantothenate production. Through reinforcing the precursor pool, refactoring the one carbon unit generation pathway, optimization of reducing power and energy supply, the D-pantothenate titer reached 34.12 g/L with the yield at 0.28 g/g glucose under fed-batch fermentation in 5-L bioreactor. With a further comparative transcriptome and metabolomics studies, the addition of citrate was implemented and 45.35 g/L D-pantothenate was accumulated with a yield of 0.31 g/g glucose. The systematic modular engineering coupled with omics studies provide useful strategies for the industrial production of D-pantothenate.


Assuntos
Escherichia coli , Engenharia Metabólica , Vias Biossintéticas , Carbono/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Fermentação , Glucose/metabolismo
11.
Nat Commun ; 12(1): 4368, 2021 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-34272383

RESUMO

Bioproduction of renewable chemicals is considered as an urgent solution for fossil energy crisis. However, despite tremendous efforts, it is still challenging to generate microbial strains that can produce target biochemical to high levels. Here, we report an example of biosynthesis of high-value and easy-recoverable derivatives built upon natural microbial pathways, leading to improvement in bioproduction efficiency. By leveraging pathways in solventogenic clostridia for co-producing acyl-CoAs, acids and alcohols as precursors, through rational screening for host strains and enzymes, systematic metabolic engineering-including elimination of putative prophages, we develop strains that can produce 20.3 g/L butyl acetate and 1.6 g/L butyl butyrate. Techno-economic analysis results suggest the economic competitiveness of our developed bioprocess. Our principles of selecting the most appropriate host for specific bioproduction and engineering microbial chassis to produce high-value and easy-separable end products may be applicable to other bioprocesses.


Assuntos
Acetatos/metabolismo , Butiratos/química , Clostridium/metabolismo , Ácidos Graxos/metabolismo , Fermentação/genética , Engenharia Metabólica/métodos , Acetilcoenzima A/metabolismo , Biocombustíveis/microbiologia , Biomassa , Clostridium/enzimologia , Clostridium/genética , Ésteres/metabolismo , Redes e Vias Metabólicas/genética , NAD/metabolismo , Proteínas/genética , Proteínas/metabolismo , Proteínas Recombinantes
12.
Int J Biol Macromol ; 179: 71-79, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33631263

RESUMO

l-lactate dehydrogenases (LDHs) has been widely studied for their ability to reduce 2-keto acids for the production of 2-hydroxy acids, whereby 2-hydroxybutyric acids (2-HBA) is among the most important fundamental building blocks for synthesizing pharmaceuticals and biodegradable materials. However, LDHs usually show low activity towards 2-keto acids with longer side chain such as 2-oxobutyric acid (2-OBA). Here rational engineering of the Plasmodium falciparum LDH loop with residue involved in the catalytic proton transfer was initially studied. By combining homology alignment and structure-based design approach, we found that changing the charge characteristics or hydrogen bond network interactions of this loop could improve enzymatic catalytic activities and stabilities towards 2-OBA. Compared with wild type, variant N197Dldh showed 1.15 times higher activity and 2.73 times higher Kcat/Km. The half-life of variant N197Dldh at 40 °C increased to 77.9 h compared with 50.4 h of wild type. Furthermore, asymmetric synthesis of (S)-2-HBA with coenzyme regeneration revealed 95.8 g/L production titer within 12 h for variant N197Dldh, 2.05 times higher than using wild type. Our study indicated the importance of loop with residues involved in the catalytic proton transfer process, and the engineered LDH would be more suitable for (S)-2-HBA production.


Assuntos
Hidroxibutiratos/síntese química , L-Lactato Desidrogenase/química , Plasmodium falciparum/enzimologia , Proteínas de Protozoários/química , Catálise , Hidroxibutiratos/química , L-Lactato Desidrogenase/genética , Plasmodium falciparum/genética , Engenharia de Proteínas , Estrutura Secundária de Proteína , Proteínas de Protozoários/genética
13.
Bioresour Technol ; 326: 124665, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33540211

RESUMO

Leucine dehydrogenase (LDH) is widely used in the preparation of L-2-aminobutyric acid (L-2-ABA), however its wide application is limited by 2-ketobutyric acid (2-OBA) inhibition. Firstly, a novel high-throughput screening method of LDH was established, specific enzyme activity and 2-OBA tolerance of Lys72Ala mutant were 33.3% higher than those of the wild type. Subsequently, we constructed a single cell comprised of ivlA, EsldhK72A, fdh and optimized expression through fine-tuning RBS intensity, so that the yield of E. coli BL21/pET28a-R3ivlA-EsldhK72A-fdh was 2.6 times higher than that of the original strain. As a result, 150 g L-threonine was transformed to 121 g L-2-ABA in 5 L fermenter with 95% molar conversion rate, and a productivity of 5.04 g·L-1·h-1, which is the highest productivity of L-2-ABA currently reported by single-cell biotransformation. In summary, our research provided a green synthesis for L-2-ABA, which has potential for industrial production of drug precursors.


Assuntos
Aminobutiratos , Escherichia coli , Aminobutiratos/metabolismo , Biotransformação , Escherichia coli/genética , Escherichia coli/metabolismo , Leucina Desidrogenase/genética , Leucina Desidrogenase/metabolismo
14.
Sheng Wu Gong Cheng Xue Bao ; 37(12): 4231-4242, 2021 Dec 25.
Artigo em Chinês | MEDLINE | ID: mdl-34984870

RESUMO

2-Hydroxybutyric acid (2-HBA) is an important intermediate for synthesizing biodegradable materials and various medicines. Chemically synthesized racemized 2-HBA requires deracemization to obtain optically pure enantiomers for industrial application. In this study, we designed a cascade biosynthesis system in Escherichia coli BL21 by coexpressing L-threonine deaminase (TD), NAD-dependent L-lactate dehydrogenase (LDH) and formate dehydrogenase (FDH) for production of optically pure (S)-2-HBA from bulk chemical L-threonine (L-Thr). To coordinate the production rate and the consumption rate of the intermediate 2-oxobutyric acid in the multi-enzyme cascade catalytic reactions, we explored promoter engineering to regulate the expression levels of TD and FDH, and developed a recombinant strain P21285FDH-T7V7827 with a tunable system to achieve a coordinated multi-enzyme expression. The recombinant strain P21285FDH-T7V7827 was able to efficiently produce (S)-2-HBA with the highest titer of 143 g/L and a molar yield of 97% achieved within 16 hours. This titer was approximately 1.83 times than that of the highest yield reported to date, showing great potential for industrial application. Our results indicated that constructing a multi-enzyme-coordinated expression system in a single cell significantly contributed to the biosynthesis of hydroxyl acids.


Assuntos
Formiato Desidrogenases , Hidroxibutiratos , Escherichia coli/genética , Treonina Desidratase
15.
BMC Ophthalmol ; 20(1): 432, 2020 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-33115419

RESUMO

BACKGROUND: At present, patients with ocular myasthenia gravis (OMG) are typically treated with systemic drugs. We investigated the use of dexamethasone injected in the peribulbar region or extraocular muscle to treat patients with OMG. METHODS: Patients with OMG were given dexamethasone via peribulbar injection or direct injection into the main paralyzed extraocular muscles, once a week, for 4-6 weeks. The severity of diplopia, blepharoptosis, eye position, and eye movement were evaluated before and after treatment. The duration of follow-up time was ≥6 months. RESULTS: Among the 14 patients with OMG who received this treatment, mean age was 38.7 ± 29.7 years. After treatment, symptoms were relieved in 12 patients (85.7%), 1 patient (7.1%) had partial response to treatment, and 1 patient (7.1%) had no response. Two patients (14.2%) experienced symptom recurrence during the follow-up period. CONCLUSIONS: Dexamethasone peribulbar or extraocular muscle injection is effective in the treatment of patients with OMG and may replace systemic drug therapy. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR2000038863 , October 7, 2020.Retrospectively registered.


Assuntos
Blefaroptose , Miastenia Gravis , Adolescente , Adulto , Idoso , Blefaroptose/induzido quimicamente , Blefaroptose/tratamento farmacológico , Criança , Dexametasona , Diplopia/tratamento farmacológico , Humanos , Pessoa de Meia-Idade , Miastenia Gravis/tratamento farmacológico , Recidiva Local de Neoplasia , Adulto Jovem
16.
Curr Opin Chem Biol ; 59: 37-46, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32454426

RESUMO

Biofuels and biochemicals derived from renewable resources are sconsidered as potential solutions for the energy crisis and associated environmental problems that human beings are facing today. However, so far the available types of bioderived chemicals are rather limited, and production efficiency is generally low. Expanding the realm of bioderived chemicals and relevant derivatives can help motivate the development of bioenergy and the general bioeconomy. Aldehydes, possessing unique reactivity, hold great promise as platform chemicals for producing a large portfolio of bioproducts. In this review, we focus on production of aldehydes from renewable bioresources and derivatization of aldehydes through chemocatalysis, biocatalysis, or de novo biosynthesis. Perspectives on combining protein engineering and cascade reactions for advanced aldehyde derivatization are also provided.


Assuntos
Aldeídos/metabolismo , Biocombustíveis , Animais , Bactérias/metabolismo , Biocatálise , Biocombustíveis/análise , Biocombustíveis/microbiologia , Biomassa , Vias Biossintéticas , Fungos/metabolismo , Lignina/metabolismo
17.
Curr Opin Biotechnol ; 64: 161-168, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32361627

RESUMO

Advances in synthetic biology and metabolic engineering across the past few decades have enabled the successful production of many novel chemicals. However, bioproduction of such chemicals is often limited by low yield and titer due to disrupted metabolic homeostasis. Finely tuning cellular metabolism to restore robust metabolic functions entails various genetic modifications, which is often not practical. Alternatively, artificial mediators capable of tailoring microbial metabolisms open a new avenue for restoring physiological functions. In this context, nanoparticle-based artificial mediators have been pursued to tune cellular metabolisms. They can not only enhance production of molecules from endogenous metabolism, but also expand bioproducts spectrum. Here, we reviewed recent advances toward the employment of nano-based artificial mediators for the tuning of cellular metabolism, with a focus on their positive effects on electron transfer and pathway flux. Perspectives for potential applications of artificial mediators for mediating microbial metabolisms in the future were also provided.


Assuntos
Engenharia Metabólica , Biologia Sintética
18.
ACS Synth Biol ; 8(4): 734-743, 2019 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-30840437

RESUMO

Optically pure 1,2-amino alcohols are highly valuable products as intermediates for chiral pharmaceutical products. Here we designed an environmentally friendly non-natural biocatalytic cascade for efficient synthesis of 1,2-amino alcohols from cheaper epoxides. A redesignated ω-transaminase PAKω-TA was tested and showed good bioactivity at a lower pH than other reported transaminases. The cascade was efficiently constructed as a single one-pot E. coli recombinant, by coupling SpEH (epoxide hydrolase), MnADH (alcohol dehydrogenase), and PAKω-TA. Furthermore, RBS regulation strategy was used to overcome the rate limiting step by increasing expression of MnADH. For cofactor regeneration and amino donor source, an interesting point was involved as that a cofactor self-sufficient system was designed by expression of GluDH. It established a "bridge" between the cofactor and the cosubstrate, such that the cofactor self-sufficient system could release cofactor (NADP+) and cosubstrate (l-Glutamine) regenerated simultaneously. The recombinant E. coli BL21 (SGMP) with cofactor self-sufficient whole-cell cascade biocatalysis showed high ee value (>99%) and high yield, with 99.6% conversion of epoxide ( S)-1a to 1,2-amino alcohol ( S)-1d in 10 h. It further converted ( S)-2a-5a to ( S)-2d-5d with varying conversion rates ranging between 65-96.4%. This study first provides one-step synthesis of optically pure 1,2-amino alcohols from ( S)-epoxides employing a synthetic redox-self-sufficient cascade.


Assuntos
Amino Álcoois/metabolismo , Proteínas de Bactérias/metabolismo , Compostos de Epóxi/metabolismo , Álcool Desidrogenase/metabolismo , Biocatálise , Escherichia coli/metabolismo , Oxirredução , Estereoisomerismo , Transaminases/metabolismo
19.
Biotechnol J ; 14(3): e1800253, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30052323

RESUMO

Unnatural amino acids (UAAs) play a key role in modern medicinal chemistry such as small molecules and peptide-based drugs with fast-growing markets. Low efficiency for natural enzymes including leucine dehydrogenase (LeuDH, EC1.4.1.9) are one major challenge for UAA production. Here, rational engineering of LeuDH from Bacillus cereus with a structure-based design approach is studied. The results achieve higher enzymatic activity and stability toward α-keto acid reduction by improving the hydrophobic and rigidity of enzymatic substrate entrance tunnel. High catalytic efficiency for variant E116V is associated with the presence of more hydrophobic tunnels that allows easy substrate diffusion, which is confirmed in absorbance spectroscopy study. For variant T45M/E116V, melting temperature and half-lives of thermal inactivation at 60 °C is 62.8 °C and 29.2 h, respectively, much higher than 48.4 °C and 3.4 h of wild type. Structural analysis indicates that an additional hydrogen bond in ß5 fold is formed in variant T45M, which results in a more rigid ß5 fold leading to better stability. Furthermore, asymmetric synthesis of α-amino acids with coenzyme regeneration reveals higher productivities for variant T45M/E116V. This study indicates the importance of substrate entrance tunnel for enzymatic activities and stability, the engineered LeuDH would better serve UAA production.


Assuntos
Aminoácidos/metabolismo , Bacillus cereus/metabolismo , Cetoácidos/metabolismo , Leucina Desidrogenase/metabolismo , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Engenharia de Proteínas/métodos , Temperatura
20.
Mater Sci Eng C Mater Biol Appl ; 91: 696-704, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-30033304

RESUMO

A nanocomposite with multi-walled carbon nanotubes (MWCNTs) coated with surface molecularly imprinted polymers (MIPs) poly(3-aminophenylboronic acid) (PAPBA) was successfully prepared via potentiodynamic electropolymerization and tested as an effective electrochemical material for epinephrine (EP) detection. The morphology and properties of the sensing material were characterized with scanning electron microscopy and electrochemical impedance spectroscopy. Compared with MWCNTs or non-imprinted polymers PAPBA modified MWCNTs electrodes, the PAPBA(MIPs)/MWCNTs modified electrode showed a lower charge transfer resistance and enhanced electrochemical performance for EP detection. The improved performance can be attributed to the large amount of specific imprinted cavities with boric acid group which can selectively adsorb EP molecule and the synergistic effect between MWCNTs and PAPBA(MIPs). The effects of pH, the molar ratio between monomer and template molecule, the cycle number of electropolymerization, and the accumulation time of the modified electrode on the sensing performance were investigated. It was found that under the optimal conditions, the PAPBA(MIPs)/MWCNTs sensor could effectively recognize EP from many possible interferents of higher concentration within a wide linear range of 0.2-800 µmol·L-1, with low detection limit of 35 nmol·L-1, high sensitivity and good discrimination. The detection of EP in human serum and real injection samples using the PAPBA(MIPs)/MWCNTs sensor also gave satisfactory results.


Assuntos
Ácidos Borônicos/química , Técnicas Eletroquímicas/métodos , Epinefrina/análise , Impressão Molecular/métodos , Nanocompostos/química , Nanotubos de Carbono/química , Carbono/química , Eletrodos , Epinefrina/sangue , Vidro/química , Humanos , Concentração de Íons de Hidrogênio , Nanotubos de Carbono/ultraestrutura , Polimerização , Reprodutibilidade dos Testes
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...