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1.
Science ; 367(6482): 1147-1151, 2020 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-32139546

RESUMO

Mycobacterium tuberculosis has an unusual outer membrane that lacks canonical porin proteins for the transport of small solutes to the periplasm. We discovered that 3,3-bis-di(methylsulfonyl)propionamide (3bMP1) inhibits the growth of M. tuberculosis, and resistance to this compound is conferred by mutation within a member of the proline-proline-glutamate (PPE) family, PPE51. Deletion of PPE51 rendered M. tuberculosis cells unable to replicate on propionamide, glucose, or glycerol. Growth was restored upon loss of the mycobacterial cell wall component phthiocerol dimycocerosate. Mutants in other proline-glutamate (PE)/PPE clusters, responsive to magnesium and phosphate, also showed a phthiocerol dimycocerosate-dependent growth compromise upon limitation of the corresponding substrate. Phthiocerol dimycocerosate determined the low permeability of the mycobacterial outer membrane, and the PE/PPE proteins apparently act as solute-specific channels.


Assuntos
Amidas/metabolismo , Proteínas de Bactérias/metabolismo , Membrana Celular/metabolismo , Glucose/metabolismo , Glicerol/metabolismo , Mycobacterium tuberculosis/metabolismo , Proteínas de Bactérias/genética , Transporte Biológico , Permeabilidade da Membrana Celular , Farmacorresistência Bacteriana/genética , Deleção de Genes , Lipídeos/química , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/genética , Compostos de Sulfidrila/química , Compostos de Sulfidrila/farmacologia
2.
World J Microbiol Biotechnol ; 36(3): 49, 2020 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-32157439

RESUMO

Glycerol is a by-product of biodiesel, and it has a great application prospect to be transformed to synthesize high value-added compounds. Pseudomonas chlororaphis GP72 isolated from the green pepper rhizosphere is a plant growth promoting rhizobacteria that can utilize amount of glycerol to synthesize phenazine-1-carboxylic acid (PCA). PCA has been commercially registered as "Shenqinmycin" in China due to its characteristics of preventing pepper blight and rice sheath blight. The aim of this study was to engineer glycerol utilization pathway in P. chlororaphis GP72. First, the two genes glpF and glpK from the glycerol metabolism pathway were overexpressed in GP72ANO separately. Then, the two genes were co-expressed in GP72ANO, improving PCA production from 729.4 mg/L to 993.4 mg/L at 36 h. Moreover, the shunt pathway was blocked to enhance glycerol utilization, resulting in 1493.3 mg/L PCA production. Additionally, we confirmed the inhibition of glpR on glycerol metabolism pathway in P. chlororaphis GP72. This study provides a good example for improving the utilization of glycerol to synthesize high value-added compounds in Pseudomonas.


Assuntos
Glicerol/metabolismo , Engenharia Metabólica/métodos , Pseudomonas chlororaphis/genética , Pseudomonas chlororaphis/metabolismo , Aquaporinas/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Capsicum/microbiologia , China , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , Regulação Bacteriana da Expressão Gênica , Técnicas de Inativação de Genes , Glicerolfosfato Desidrogenase/genética , Redes e Vias Metabólicas/genética , Fenazinas/metabolismo , Proteínas Repressoras/genética , Rizosfera
3.
Bioresour Technol ; 303: 122954, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32045863

RESUMO

Economic assessment of bio-flocculant production process has been carried out by SuperPro Designer where extracellular-polymeric substances (EPS) were produced using activated sludge fortified with crude glycerol in fermenter followed by centrifugation. Considering EPS concentration of 60 g/L in production fermenter at 96 h, the unit production cost for slime EPS was estimated to be $ 0.95/L. The unit price of S-EPS was sensitive to inoculum size and EPS productivity (EPS concentration and fermentation time) in the fermented broth. Economic analysis was also conducted for EPS aided leachate treatment. The unit leachate treatment cost was 7.78 $/m3 and was sensitive to S-EPS unit production cost. To get same leachate treatment cost as current industrial practice (4 $/m3), S-EPS unit production cost should lower down to $ 0.5/L. The process has several advantages: 1) sludge and crude glycerol valorization for bio-flocculant production 2) Leachate treatment using environment friendly bio-flocculant.


Assuntos
Glicerol , Esgotos , Reatores Biológicos , Fermentação , Floculação
4.
J Environ Manage ; 256: 109964, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31989983

RESUMO

The contamination of water resources by nitrate is a global problem. Indeed, traditional treatment technologies are not able to remove this ion from water. Alternatively, biological denitrification is a useful technique for natural water nitrate removal. This study aimed to evaluate the use of glycerol as a carbon source for drinking water nitrate removal via denitrification in a reactor using microorganisms from natural biomass. The experiment was carried out in a continuous fixed bed reactor using immobilised microorganisms from the vegetal Phyllostachys aurea. The tests were started in batch mode to provide cells growth and further immobilisation on the support. Then, the treatment experiments were accomplished in an up-flow continuous reactor. Ethanol was used as the primary carbon source, and it was gradually replaced by glycerol. The C:N (carbon to nitrogen) ratio and the hydraulic residence time (HRT) were evaluated. It was possible to remove 98.14% of nitrate using a C:N ratio and HRT of 3:1 and 1.51 days, respectively. The results have demonstrated that glycerol is a potential carbon source for denitrification in a continuous reactor using immobilised cells from natural biomass.


Assuntos
Água Potável , Purificação da Água , Biomassa , Reatores Biológicos , Carbono , Desnitrificação , Glicerol , Nitratos , Nitrogênio
5.
J Agric Food Chem ; 68(4): 989-997, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31909616

RESUMO

In the previous studies, gemini lipoamino acids (GLAA) were always synthesized by complex multistep organic synthesis, which involved a large number of byproducts and organic solvents. To develop a straightforward, efficient, and renewable synthesis strategy for GLAA, in this study, a type of novel green solvents, natural deep eutectic solvents (NADESs), were adopted as the solvents for these reactions. Five commercial enzymes were involved in the enzyme screening section, and Candida antarctica lipase B (CALB) tended to have the best performance in NADESs systems. The optimization procedure was performed using the Taguchi crossed array method and the highest yield of GLAA (59.14 ± 0.51%) was obtained in choline chloride-glycerol (C-Gly). The purification procedure was carried out with ethyl acetate and water, and the isolate yield ranged from 86.31 ± 2.36 to 91.34 ± 2.26%. With 10 times recycling, the yield of GLAA in C-Gly decreased from 59.14 ± 0.51 to 51.31 ± 0.68%. Interestingly, a synergistic effect of CALB and NADESs was found in the enzymatic synthesis of GLAA, which can be attributed to fatty acids being activated by chloride ions via hydrogen-bonding interactions and resulting in an enhancement in its electron-attracting ability.


Assuntos
Aminoácidos/síntese química , Proteínas Fúngicas/química , Lipase/química , Aminoácidos/química , Catálise , Glicerol/química , Ligações de Hidrogênio , Solventes/química
6.
AAPS PharmSciTech ; 21(2): 37, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31897804

RESUMO

Patients who suffer from dysphagia have difficulty in swallowing hard tablets and capsules; hence, gelatin-based soft-chew dosages are used as an alternative and novel drug delivery approach to overcome this problem. However, the conventional method of producing gelatin-based soft-chew dosages has many potential issues. The objective of this study was to use glycerol and the hot-melt extrusion technique to address potential issues and optimize the formulation. Gelatin, acetaminophen, saccharin, xylitol, and sodium chloride and six different ratios of water and glycerol were used in the seven formulations. Extrusion process temperature of formulations 1-6 and formulation 7 were 90°C and 140°C, respectively. Near-infrared spectra were collected during extrusion to monitor quality consistency. Scanning electron microscopic images of the cross-section of the soft-chew dosages were recorded. Differential scanning calorimetry (DSC) was used to characterize the crystal states of each formulation. Texture profile analysis was used to evaluate the physical properties of the tablets. In vitro drug release characteristics were studied. A 45-day stability study was carried out to evaluate the stability of each formulation. Near-infrared spectra showed that formulations 1-6 were uniform while formulation 7 was not. From the DSC results, formulations 1 and 2 showed crystallinity of acetaminophen. Formulation 5 displayed the desired physical and chemical stability in texture profile analysis and in the in vitro drug release studies. By using glycerol and hot-melt extrusion, the potential issues of conventional methods were successfully addressed.


Assuntos
Acetaminofen/administração & dosagem , Analgésicos não Entorpecentes/administração & dosagem , Acetaminofen/análise , Acetaminofen/química , Administração Oral , Analgésicos não Entorpecentes/análise , Analgésicos não Entorpecentes/química , Varredura Diferencial de Calorimetria , Composição de Medicamentos , Liberação Controlada de Fármacos , Excipientes , Gelatina , Glicerol , Solubilidade , Espectroscopia de Luz Próxima ao Infravermelho
7.
J Agric Food Chem ; 68(5): 1347-1353, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31961681

RESUMO

A facile approach is introduced here for the synthesis of rare ketoses from glycerol and d-/l-glyceraldehyde (d-/l-GA). The reactions were carried out in a one-pot multienzyme fashion in which the only carbon source is glycerol. In the enzymatic cascade, glycerol is phosphorylated and then oxidized at C2 to afford dihydroxyacetone phosphate (DHAP), the key donor for enzymatic aldol reaction. Meanwhile, the primary alcohol of glycerol is also oxidized to give the acceptor molecule GA in situ (d- or l-isomer could be formed stereospecifically with either alditol oxidase or horse liver alcohol dehydrogenase). Different DHAP-dependent aldolases were used to generate the aldol adducts (rare ketohexose phosphates) with various stereoconfigurations and diastereomeric ratios. It is worth noting that the enzyme that catalyzes the phosphorylation reaction in the first step could also help recycle the phosphate in the last step to provide free rare sugar molecules. This study provides a useful method for rare ketose synthesis on a 100 mg to g scale, starting from relatively inexpensive materials which solved the problem of supplying both glycerol 3-phosphate and GA in our previous work. It also demonstrates an example of green synthesis due to highly efficient carbon usage and recycling of cofactors.


Assuntos
Álcool Desidrogenase/química , Aldeído Liases/química , Glicerol/química , Cetoses/química , Animais , Biocatálise , Fosfato de Di-Hidroxiacetona/química , Cavalos , Fosforilação
8.
Bioresour Technol ; 297: 122439, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31810740

RESUMO

In the present study, a combination of phytohormones (indole acetic acid and kinetin) was augmented in nitrogen-limited medium to achieve higher biomass and lipid yield in Graesiella emersonii NC-M1 and Chlorophyta sp. NC-M5. This condition was recorded with a 2.3- and 2.5-fold increase in biomass and lipid yield for Graesiella emersonii NC-M1 compared to the nitrogen-limited condition. Also, this condition showed a 1.6- and 1.08-fold increase in lipid yield and neutral lipid compared to the standard condition. Phytohormones addition also reduced oxidative damage caused by nitrogen-limitation and enhanced monounsaturated fatty acid content. Further, a 5.2- and 3.17-fold enhance in expression level of GPAT and DGAT genes were noticed under nitrogen-limited medium supplemented with phytohormones compared to control.


Assuntos
Microalgas , Biocombustíveis , Biomassa , Diacilglicerol O-Aciltransferase , Ácidos Graxos , Glicerol , Ácidos Indolacéticos , Cinetina , Lipídeos , Nitrogênio , Fosfatos
9.
Bioresour Technol ; 297: 122404, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31757613

RESUMO

In this study, cost simulations were made based on 20 million L blended biodiesel B-10 production per year using INRS and conventional process. In case of INRS process, microbial lipid was produced by T. oleaginosus using washed municipal secondary sludge fortified with crude glycerol while lipid was extracted from wet biomass using biodegradable surfactant and petroleum-diesel (PD). The conventional process uses commercial substrates for lipid production and organic solvents for lipid extraction from dry biomass. The unit B-10 production cost of INRS process was estimated to be $ 0.72/L for an annual capacity of 20 million L, which is 9.5 times more economical than conventional biodiesel production process. For INRS process, the unit B-10 biodiesel production cost was sensitive to plant capacity and lipid productivity during the fermentation. INRS process exhibited positive net energy gain and positive GHG capture, which proves to be energetically and environmentally viable.


Assuntos
Biocombustíveis , Glicerol , Biomassa , Lipídeos , Esgotos
10.
Bioresour Technol ; 297: 122509, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31812914

RESUMO

Dunaliella salina is well-known for its high content in carotenoids and glycerol. Nevertheless, Dunaliella salina has also a high content in lipids, including polar lipids, which are suitable for nutraceutical/cosmeceutical applications. This work proposes a sustainable process to maximise the potential of Dunaliella salina for the production of distinct fractions of carotenoids, glycerol, polar lipids and proteins, which may contribute to improve the revenues of the microalgae industry. In this work, extraction with non-hazardous solvents and organic solvent nanofiltration are integrated, in order to obtain added-value products and glycerol. Also, aiming to separate carotenoids from glycerides, a saponification process is proposed. High overall recoveries were obtained for carotenoids (85%), glycerol (86%), polar lipids (94%) and proteins (95%). In order to evaluate the profitability of the proposed biorefinery, an economic assessment was accomplished. Both CAPEX and OPEX (Capital and Operating expenditure) were calculated, likewise the Return of Investment (ROI).


Assuntos
Carotenoides , Microalgas , Glicerídeos , Glicerol , Lipídeos
11.
Food Chem ; 305: 125479, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31505418

RESUMO

1-o-Galloylglycerol (GG) was synthesized by the enzymatic glycerolysis of propyl gallate (PG) using a food-grade lipase (Lipozyme® 435). The reaction conditions affecting the yield of GG were optimized and a yield of 76.9% ±â€¯1.2% was obtained. GG was characterized by various techniques after being separated from the reaction mixture using liquid-liquid extraction. The water solubility and hydrophilicity of GG were significantly higher than those of gallic acid (GA) and PG. The antioxidant properties, measured by the ferric reducing antioxidant power (FRAP) and hydrogen peroxide (H2O2) scavenging assays, showed that GG exhibited the highest scavenging capacity (GG > GA > PG). From the results of the 1,1-diphenyl-2-picrylhydrazyl (DPPH•) and 2,2'-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS•+) assays, GG and GA exhibited greater scavenging capacity than PG (GG = GA > PG). These results suggest that GG may be used as a water-soluble antioxidant alternative to GA for food and cosmetic applications.


Assuntos
Antioxidantes/metabolismo , Antioxidantes/farmacologia , Ácido Gálico/análogos & derivados , Glicerol/análogos & derivados , Antioxidantes/química , Ácido Gálico/química , Ácido Gálico/metabolismo , Ácido Gálico/farmacologia , Glicerol/química , Glicerol/metabolismo , Glicerol/farmacologia , Peróxido de Hidrogênio/química , Lipase/metabolismo , Extração Líquido-Líquido , Espectroscopia de Ressonância Magnética , Galato de Propila/química , Solubilidade , Temperatura Ambiente
12.
Sci Total Environ ; 702: 134911, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31733546

RESUMO

Development of cost effective and highly efficient process for bio-based succinic acid (SA) production is a main concern for industry. The metabolically engineered Y. lipolytica strain PGC01003 was successfully used for SA production with high titre. However, this strain possesses as main drawback with a low growth rate when glycerol is used as a feedstock. Herein, gene GUT1, encoding glycerol kinase, was overexpressed in strain PGC01003 with the aim to improve glycerol uptake capacity. In the resulting strain RIY420, glycerol uptake was 13.5% higher than for the parental strain. GUT1 gene overexpression also positively influences SA production. In batch bioreactor, SA titre, yield and productivity were 32%, 39% and 143% higher, respectively, than for the parental strain PGC01003. Using a glycerol feeding strategy, SA titre, yield and productivity were further improved by 11%, 5% and 10%, respectively. Moreover, the process duration to yield the highest concentration of SA in the culture supernatant was reduced by 9%. This demonstrated the contribution of metabolically engineered strain RIY420 to lower SA process cost and increase the efficiency of bio-based SA production.


Assuntos
Glicerol/metabolismo , Ácido Succínico/metabolismo , Yarrowia/fisiologia , Transporte Biológico , Reatores Biológicos , Engenharia Metabólica , Saccharomyces cerevisiae
13.
Food Chem ; 305: 125453, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31505417

RESUMO

Impact of glycerol and sorbitol on assembly of iron-bound ovotransferrin (OVT) into nanofibrils was investigated. Thioflavin T fluorescence result indicated that the presence of glycerol or sorbitol could reduce the rate of OVT fibrillation. Sodium dodecyl sulfate polyacrylamide gel electrophoresis demonstrated that 60% sorbitol could retard hydrolysis of OVT completely for a period of time during thermal treatment, and decoupling hydrolysis from fibril self-assembly helped to identify the building blocks of OVT nanofibrils. OVT nanofibrils were composed of both intact OVT monomers and OVT-derived peptides. Influence of glycerol and sorbitol on morphology of OVT nanofibrils was studied using atomic force microscopy. The presence of glycerol or sorbitol shortened OVT nanofibrils, and the presence of 60% glycerol or sorbitol could increase thickness of OVT nanofibrils. Hopefully, this work may provide new insight about building blocks of protein nanofibrils and impact of polyols on protein fibrillation.


Assuntos
Conalbumina/química , Glicerol/química , Nanoestruturas/química , Sorbitol/química , Temperatura Alta , Interações Hidrofóbicas e Hidrofílicas , Microscopia de Força Atômica , Propriedades de Superfície
14.
Food Chem ; 308: 125596, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-31648097

RESUMO

The protective mechanism of glycerol on ß-lactoglobulin were studied in 0-60% glycerol solutions by experimental and molecular simulation approaches. Results showed that the stability of ß-lactoglobulin increased with glycerol concentration, with little secondary structure changes induced by glycerol. The tertiary structure altered slightly with glycerol concentration, resulting in a stronger near UV circular dichroism signal and intrinsic tryptophan fluorescence quenching, indicating aromatic side chains closer to hydrophobic microenvironment. The Rg of ß-lactoglobulin increased with glycerol concentration without dimer dissociation, due to expansion of the quaternary structures. Moreover, the flexibility (RMSF) of ß-lactoglobulin decreased by glycerol. Distance between areas enclosing Asp33 and Arg40 from separate chains did not increase, suggesting possibly reinforced electrostatic attractions. In conclusion, the stabilization of ß-lactoglobulin in glycerol solution is probably the comprehensive results of the decreased molecular flexibility, the strengthened hydrophobic interaction in individual chain, and the possibly reinforced electrostatic attractions between two chains of ß-lactoglobulin.


Assuntos
Glicerol/química , Lactoglobulinas/química , Dicroísmo Circular , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína
15.
Sci Total Environ ; 705: 135137, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-31846815

RESUMO

Glycerol is a by-product produced from biodiesel, fatty acid, soap and bioethanol industries. Today, the value of glycerol is decreasing in the global market due to glycerol surplus, which primarily resulted from the speedy expansion of biodiesel producers around the world. Numerous studies have proposed ways of managing and treating glycerol, as well as converting it into value-added compounds. The electrochemical conversion method is preferred for this transformation due to its simplicity and hence, it is discussed in detail. Additionally, the factors that could affect the process mechanisms and products distribution in the electrochemical process, including electrodes materials, pH of electrolyte, applied potential, current density, temperature and additives are also thoroughly explained. Value-added compounds that can be produced from the electrochemical conversion of glycerol include glyceraldehyde, dihydroxyacetone, glycolic acid, glyceric acid, lactic acid, 1,2-propanediol, 1,3-propanediol, tartronic acid and mesoxalic acid. These compounds are found to have broad applications in cosmetics, pharmaceutical, food and polymer industries are also described. This review will be devoted to a comprehensive overview of the current scenario in the glycerol electrochemical conversion, the factors affecting the mechanism pathways, reaction rates, product selectivity and yield. Possible outcomes obtained from the process and their benefits to the industries are discussed. The utilization of solid acid catalysts as additives for future studies is also suggested.


Assuntos
Biocombustíveis , Glicerol , Cinética , Sabões
16.
Biophys Chem ; 257: 106274, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31877449

RESUMO

An orderly investigation of the levels of secondary and tertiary structures, kinetics of tertiary structural changes, and self diffusion coefficient of lysozyme and cytochrome c in the 0-70% (weight/volume) range of glycerol is reported. While secondary structural propensity of both proteins is larger in glycerol, results for tertiary structure and translational diffusion coefficient with increasing glycerol provide two contrasting depictions - lysozyme becomes increasingly compact, plausibly due to disulfide bridge constraints, but cytochrome c expands and loses the tertiary structure. The chain expansion and contraction corresponding to loss and reformation of tertiary structure of cytochrome c are ultrafast that occur in the submillisecond bin. Changes in protein conformation appear in as little as 2% glycerol, and the results suggest that glycerol does not unfold the protein but reversibly destabilizes to quasi-native state(s). These observations make one ponder whether results of studies on protein dynamics, relaxation, and conformational substates reported in literature can be associated with native-state properties.


Assuntos
Citocromos c/química , Glicerol/química , Muramidase/química , Água/química , Difusão , Cinética , Dobramento de Proteína , Estrutura Secundária de Proteína , Termodinâmica
17.
Food Chem ; 307: 125542, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31639573

RESUMO

This study aimed to develop a headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) method for the quantification of 3-monochloropropane-1,2-diol fatty acid esters (3-MCPDEs) and 2-monochloropropane-1,3-diol fatty acid esters (2-MCPDEs), and semi-quantification of glycidyl fatty acid esters (GEs) in edible oils. A central composite design was implemented to optimize the derivatization temperature and extraction time, which were 100 °C and 80 min, respectively. HS-SPME coupled with in-situ derivatization was more straightforward (three steps) and sensitive, with a limit of detection of 16% (3.9 µg/L) and 11% (5.3 µg/L) higher than that of liquid injection method, for 3-MCPD and 2-MCPD, respectively. The recoveries of 3-MCPD and 2-MCPD were in the range of 91.1% to 102.1%, with a relative standard deviation ranging from 0.08 to 9.29%. The validated methodology was successfully applied to oil samples. Further efforts will focus on shortening the extraction time, as 80 min is relatively long.


Assuntos
Ésteres/análise , Cromatografia Gasosa-Espectrometria de Massas , Glicerol/análogos & derivados , Óleos Vegetais/química , Microextração em Fase Sólida/métodos , alfa-Cloridrina/química , Ésteres/química , Ácidos Graxos/química , Contaminação de Alimentos/análise , Glicerol/química , Limite de Detecção
18.
J Agric Food Chem ; 68(2): 561-566, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31840510

RESUMO

2-Hydroxyphenazine (2-OH-PHZ) is an effective biocontrol antibiotic secreted by Pseudomonas chlororaphis GP72AN and is transformed from phenazine-1-carboxylic acid (PCA). PCA is the main component of the recently registered biopesticide "Shenqinmycin". Previous research showed that 2-OH-PHZ was better in controlling wheat take-all disease than PCA; however, 2-OH-PHZ production was low under natural conditions. Herein, we confirmed that PCA induced reactive oxygen species in its host P. chlororaphis GP72AN and that the addition of DTT improved PCA production by 1.8-fold, whereas the supplementation of K3[Fe(CN)6] and H2O2 increased the conversion rate of PCA to 2-OH-PHZ. Finally, a two-stage fermentation strategy combining the addition of DTT at 12 h and H2O2 at 24 h enhanced 2-OH-PHZ production. Taken together, the two-stage fermentation strategy was designed to enhance 2-OH-PHZ production for the first time, and it provided a valuable reference for the fermentation of other antibiotics.


Assuntos
Antibacterianos/biossíntese , Glicerol/metabolismo , Microbiologia Industrial/métodos , Pseudomonas chlororaphis/metabolismo , Proteínas de Bactérias/metabolismo , Meios de Cultura/química , Meios de Cultura/metabolismo , Fermentação , Peróxido de Hidrogênio/metabolismo , Fenazinas/metabolismo , Espécies Reativas de Oxigênio/metabolismo
19.
Bioresour Technol ; 299: 122600, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31864087

RESUMO

To improve 3-hydroxypropionic acid (3-HP) production by Escherichia coli, glycerol accumulation needs to be reduced. To accomplish this, we constructed a novel E. coli strain that overexpresses the endogenous aldehyde dehydrogenase gene (puuC) under the control of a strong promoter. The fermentation performance of the engineered strain was significantly improved compared to that of the parental control strain in the presence of glucose and xylose. We also inactivated the puu operon repressor gene, puuR, which resulted in a decrease in glycerol accumulation and an increase in 3-HP production through the co-fermentation of glucose and xylose. Through fed-batch fermentation by utilizing glucose and xylose, the engineered strain, JHS_Δgypr-PT7, produced 53.7 g/L 3-HP and accumulated 1.5 g/L glycerol. This combination strategy, wherein we overexpressed the endogenous puuC gene from a strong promoter and eliminate its transcriptional repression, may be extended to rebalance another biochemical pathway.


Assuntos
Escherichia coli , Ácido Láctico , Fermentação , Glicerol , Ácido Láctico/análogos & derivados , Engenharia Metabólica , Xilose
20.
World J Microbiol Biotechnol ; 36(1): 2, 2019 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-31811394

RESUMO

"Dirty" glycerol from biodiesel production is having a considerable environmental impact since its disposal is expensive and difficult. The increased biodiesel production in the last two decades has forced glycerol prices down, thereby making it now unprofitable for chemical companies to produce. The problem lies with the impurities of the biodiesel conversion process usually ending up within the crude glycerol fraction. These impurities are often too costly to purify with current processes, particularly for small scale producers. A wide variety of industries, including the paint, tobacco, food and pharmaceutical industries, utilize glycerol as part of their technology or products. However, the crude glycerol from biodiesel production is not of a high enough grade to be used in these industries. Biodiesel-produced crude glycerol is therefore cheap, readily available and presents itself as an attractive carbon source for industrial microbial production systems synthesizing value-added products. This mini-review will look at (a) microbial production processes which use crude glycerol to produce high-value products (product-driven research) and (b) genetic engineering of microbes which is aimed at improving microbial "dirty" glycerol utilization (substrate driven research).


Assuntos
Biocombustíveis , Fermentação , Glicerol/metabolismo , Microbiologia Industrial , Bactérias/genética , Bactérias/metabolismo , Carbono , Engenharia Genética
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