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1.
Nat Commun ; 13(1): 4691, 2022 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-35948538

RESUMO

Clostridium acetobutylicum is a promising biocatalyst for the renewable production of n-butanol. Several metabolic strategies have already been developed to increase butanol yields, most often based on carbon pathway redirection. However, it has previously demonstrated that the activities of both ferredoxin-NADP+ reductase and ferredoxin-NAD+ reductase, whose encoding genes remain unknown, are necessary to produce the NADPH and the extra NADH needed for butanol synthesis under solventogenic conditions. Here, we purify, identify and partially characterize the proteins responsible for both activities and demonstrate the involvement of the identified enzymes in butanol synthesis through a reverse genetic approach. We further demonstrate the yield of butanol formation is limited by the level of expression of CA_C0764, the ferredoxin-NADP+ reductase encoding gene and the bcd operon, encoding a ferredoxin-NAD+ reductase. The integration of these enzymes into metabolic engineering strategies introduces opportunities for developing a homobutanologenic C. acetobutylicum strain.


Assuntos
Clostridium acetobutylicum , Butanóis/metabolismo , Clostridium/metabolismo , Clostridium acetobutylicum/genética , Clostridium acetobutylicum/metabolismo , Elétrons , Fermentação , Ferredoxina-NADP Redutase/metabolismo , Ferredoxinas/metabolismo , NAD/metabolismo , NADP/metabolismo , Oxirredutases/genética , Oxirredutases/metabolismo
2.
Acta Crystallogr F Struct Biol Commun ; 78(Pt 8): 289-296, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35924596

RESUMO

Levansucrases are biotechnologically interesting fructosyltransferases due to their potential use in the enzymatic or chemo-enzymatic synthesis of glycosides of non-natural substrates relevant to pharmaceutical applications. The structure of Erwinia tasmaniensis levansucrase in complex with (S)-1,2,4-butanetriol and its biochemical characterization suggests the possible application of short aliphatic moieties containing polyols with defined stereocentres in fructosylation biotechnology. The structural information revealed that (S)-1,2,4-butanetriol mimics the natural substrate. The preference of the protein towards a specific 1,2,4-butanetriol enantiomer was assessed using microscale thermophoresis binding assays. Furthermore, the results obtained and the structural comparison of levansucrases and inulosucrases suggest that the fructose binding modes could differ in fructosyltransferases from Gram-positive and Gram-negative bacteria.


Assuntos
Antibacterianos , Bactérias Gram-Negativas , Butanóis , Cristalografia por Raios X , Erwinia , Bactérias Gram-Positivas , Hexosiltransferases
3.
Food Chem ; 393: 133379, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-35691063

RESUMO

T-butanol is widely used in three-phase partitioning (TPP). This study used deep eutectic solvents (DESs) to substitute t-butanol for tomato peroxidase (POD) purification. DES-5 (menthol and octanoic acid) was screened as the optimal solvent. The extraction process was optimized using single-factor experiments. Thereafter, the major three factors were optimized by response surface methodology (RSM). When the ammonium sulfate ((NH4)2SO4) concentration was 42%, DES: crude extract (v/v) was 2:1, pH was 5.7, and extraction temperature was 30 °C, the recovery and purification fold reached a maximum of 104.71% and 9.76, respectively. The obtained tomato POD was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), which showed that this system could effectively purify POD. Finally, recycling studies indicated the good cycle stability of the DES. This TPP based on DESs is greener and more efficient, indicating that DESs can be good alternative solvents for further applications of TPP.


Assuntos
Lycopersicon esculentum , 1-Butanol , Butanóis , Peroxidase , Solventes , terc-Butil Álcool
4.
J Hazard Mater ; 437: 129360, 2022 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-35738171

RESUMO

To increase the use of biofuels in diesel engines and reduce harmful emissions emitted from diesel fuel, biodiesel and higher alcohols are fuel sources at the forefront of research. The aim of this study is to understand the effect of water-containing n-butanol-biodiesel blends on regulated emissions, emphasizing nitrogen oxides (NOx) and polycyclic aromatic hydrocarbons (PAHs), which are harmful for the environment and engine durability. 10% n-butanol (B90Bu10) and 10% n-butanol-1% water (B89Bu10W1) were blended with 89% waste-oil biodiesel and tested in a diesel engine at four engine loads at a constant engine speed. PAH samples were analyzed using gas chromatography-mass spectrometry (GC-MS). Results showed B100, B90Bu10 and B89Bu10W1 blends increased break specific fuel consumption (BSFC), exhaust gas temperatures (EGT), carbon monoxide (CO) and hydrocarbon (HC) emissions. However, NOx emissions significantly decreased using butanol and butanol-water blends. Compared to diesel, biodiesel and blended fuels significantly reduced total PAHs and PAH toxicity up to 75.0%. However, B89Bu10W1 increased total PAH and PAH toxicity by 35.7%. Overall, the biodiesel-butanol blend, which emits less carcinogenic pollutants and low-cyclic PAHs than water-containing fuel, was found to reduce the risk of wetstacking in diesel engines operating under low loads.


Assuntos
Biocombustíveis , Hidrocarbonetos Policíclicos Aromáticos , 1-Butanol , Biocombustíveis/análise , Butanóis , Gasolina/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Emissões de Veículos/análise , Água/química
5.
Microb Cell Fact ; 21(1): 130, 2022 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-35761287

RESUMO

BACKGROUND: Lignocellulosic biomass is recognized as an effective potential substrate for biobutanol production. Though many pretreatment and detoxification methods have been set up, the fermentability of detoxicated lignocellulosic substrate is still far lower than that of starchy feedstocks. On the other hand, the number of recent efforts on rational metabolic engineering approaches to increase butanol production in Clostridium strains is also quite limited, demonstrating the physiological complexity of solventogenic clostridia. In fact, the strain performance is greatly impacted by process control. developing efficient process control strategies could be a feasible solution to this problem. RESULTS: In this study, oxidoreduction potential (ORP) controlling was applied to increase the fermentability of enzymatically hydrolyzed steam-exploded corn stover (SECS) for butanol production. When ORP of detoxicated SECS was controlled at - 350 mV, the period of fermentation was shortened by 6 h with an increase of 27.5% in the total solvent (to 18.1 g/L) and 34.2% in butanol (to 10.2 g/L) respectively. Silico modeling revealed that the fluxes of NADPH, NADH and ATP strongly differed between the different scenarios. Quantitative analysis showed that intracellular concentrations of ATP, NADPH/NADP+, and NADH/NAD+ were increased by 25.1%, 81.8%, and 62.5%. ORP controlling also resulted in a 2.1-fold increase in butyraldehyde dehydrogenase, a 1.2-fold increase in butanol dehydrogenase and 29% increase in the cell integrity. CONCLUSION: ORP control strategy effectively changed the intracellular metabolic spectrum and significantly improved Clostridium cell growth and butanol production. The working mechanism can be summarized into three aspects: First, Glycolysis and TCA circulation pathways were strengthened through key nodes such as pyruvate carboxylase [EC: 6.4.1.1], which provided sufficient NADH and NADPH for the cell. Second, sufficient ATP was provided to avoid "acid crash". Third, the key enzymes activities regulating butanol biosynthesis and cell membrane integrity were improved.


Assuntos
Butanóis , Clostridium acetobutylicum , 1-Butanol/metabolismo , Trifosfato de Adenosina/metabolismo , Butanóis/metabolismo , Clostridium/metabolismo , Clostridium acetobutylicum/metabolismo , Fermentação , NAD/metabolismo , NADP/metabolismo , Vapor , Zea mays/metabolismo
6.
Microbiol Spectr ; 10(3): e0082822, 2022 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-35647694

RESUMO

Carbapenem-resistant Enterobacteriaceae (CRE) are an urgent threat to public health requiring the development of novel therapies. TP0586532 is a novel non-hydroxamate LpxC inhibitor that inhibits the synthesis of lipopolysaccharides, which are components of the outer membranes of Gram-negative bacteria. Based on the mechanism of action of TP0586532, we hypothesized that it might enhance the antibacterial activity of other antibiotics by increasing the permeability of the outer bacterial membrane. The combination of TP0586532 with meropenem, amikacin, cefepime, piperacillin, and tigecycline showed synergistic and additive effects against carbapenem-susceptible Klebsiella pneumoniae and Escherichia coli. Checkerboard experiments against 21 carbapenem-resistant K. pneumoniae and E. coli strains (13 blaKPC+, 5 blaNDM-1+, 2 blaVIM+, and 1 blaIMP+) showed that the combination of TP0586532 with meropenem yielded synergistic and additive effects against 9 and 12 strains, respectively. In a time-kill assay examining 12 CRE strains, synergistic effects were observed when TP0586532 was combined with meropenem against many of the strains. A membrane permeability assay using ethidium bromide (EtBr) was performed to investigate the mechanism of the potentiating effect. TP0586532 increased the influx of EtBr into a CRE strain, suggesting that TP0586532 increased membrane permeability and facilitated intracellular access for the antibiotics. Our study demonstrates that TP0586532 potentiates the in vitro antibacterial activity of meropenem against CRE. Combination therapy consisting of TP0586532 and meropenem has potential as a treatment for CRE infections. IMPORTANCE Carbapenem-resistant Enterobacteriaceae (CRE) are an urgent public health threat, as therapeutic options are limited. TP0586532 is a novel LpxC inhibitor that inhibits the synthesis of lipopolysaccharides in the outer membranes of Gram-negative bacteria. Here, we demonstrated the potentiating effects of TP0586532 on the antibacterial activity of meropenem against CRE harboring various types of carbapenemase genes (blaKPC+, blaNDM-1+ blaVIM+, and blaIMP+). TP0586532 also augmented the bactericidal effects of meropenem against CRE strains, even against those with a high level of resistance to meropenem. The potentiating effects were suggested to be mediated by an increase in bacterial membrane permeability. Our study revealed that a combination therapy consisting of TP0586532 and meropenem has the potential to be a novel therapeutic option for CRE infections.


Assuntos
Enterobacteriáceas Resistentes a Carbapenêmicos , Infecções por Enterobacteriaceae , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Butanóis/farmacologia , Enterobacteriáceas Resistentes a Carbapenêmicos/genética , Carbapenêmicos/farmacologia , Infecções por Enterobacteriaceae/tratamento farmacológico , Infecções por Enterobacteriaceae/microbiologia , Escherichia coli/genética , Bactérias Gram-Negativas , Humanos , Imidazóis/farmacologia , Inosina Monofosfato/farmacologia , Klebsiella pneumoniae/genética , Meropeném/farmacologia , Testes de Sensibilidade Microbiana , beta-Lactamases/genética
7.
Chemosphere ; 305: 135480, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35760127

RESUMO

N-butanol has unique physicochemical and combustion properties, similar to gasoline, which makes it an environmentally friendly alternative to conventional fuels. To improve the efficiency, the dehydration of butanol is necessary. This paper aims to investigate the performance of Deep Eutectic Solvents (DESs) based membranes for the dehydration of n-butanol by the pervaporation process. Three DES with different combinations of hydrogen bond donors and acceptors, i.e., DL-menthol: Lauric acid (DES), DL-menthol-Palmitic acid (DES), and [TETA] Cl: Thymol (DES), were used. We hypothesized that (i) incorporation of hydrophobic DES would increase the hydrophobicity of the membranes; (ii) specific functional groups (phenolic group, amine group) in DESs would enhance the butanol-philic character of membranes, and (iii) hydrophobic DESs would increase the butanol separation efficiency and permeability of membranes. FTIR analysis and physicochemical parameters of the resultant liquid mixture validated the DESs' production. The DESs were then filled into the permeable support, resulting in supported liquid membranes (SLMs). An additional layer of polydimethylsiloxane (PDMS) was coated directly on the DES-PSf layer to prevent leaching out of DES. A feed containing a 6 wt % aqueous solution of butanol under varying temperatures was studied. The results showed that among all membranes, [TETA] Cl: Thymol DES-based membrane showed the highest sorption of 36% at room temperature. The introduction of DES in membranes resulted in a remarkable increase in the separation factor while sustaining a reasonable flux. Among all the membranes, the DL-menthol: Lauric acid (DES) based membrane exhibited the highest separation factor of 57 with a total flux of 0.11 kg/m2. h. Significantly high butanol-water separation was attributed to the low viscosity and high butanol solubility of the chosen DES, which makes it a suitable substitute to conventional ILs.


Assuntos
1-Butanol , Butanóis , Solventes Eutéticos Profundos , Desidratação , Humanos , Mentol , Solventes/química , Timol , Água
8.
J Chromatogr A ; 1676: 463210, 2022 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-35700573

RESUMO

Butanol is a common organic solvent used in latex paint, and one of its isomers, tert-butanol, is toxic and can cause potential harm to the human body. Therefore, it is of great significance to develop a qualitative and quantitative detection method for butanol isomers. In this study, we combined the advantages of rapid detection of proton transfer reaction mass spectrometry (PTR-MS) with the separation and qualitative capabilities of gas chromatography-mass spectrometry (GC-MS) to achieve the detection of isomers, building a fast gas chromatography proton transfer reaction mass spectrometry (FastGC-PTR-MS) equipment. Firstly, the developed technology was optimized using standard samples of several common volatile organic compounds. The retention times of acetonitrile, acetone, and alcohols were less than 50 s, and the retention times of the benzene series were less than 110 s, on the premise that these isomers could be basically separated (resolution R > 1.0). Compared with a commercial GC-MS equipment, the detection times were shortened by 5-6 times and 2-4 times, respectively. Then the FastGC-PTR-MS was applied to detect the isomers of butanol in latex paint. The results showed that the headspace of brand D latex paint mainly contained five substances: tert-butanol, n-butanol, acetaldehyde, methanol, and acetone. Tert-butanol and n-butanol could be completely separated (R > 1.5). The concentration of tert-butanol was 4.41 ppmv, far below the 100 ppmv maximum allowable workplace concentration. The developed FastGC-PTR-MS can be used for rapid qualitative and quantitative detection of butanol isomers in latex paint. The new equipment has the potential to play an important role in indoor environmental safety applications.


Assuntos
Butanóis , Látex , Pintura , Butanóis/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Humanos , Látex/química , Pintura/análise
9.
Microb Cell Fact ; 21(1): 85, 2022 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-35568911

RESUMO

BACKGROUND: The replacement of fossil fuels and petrochemicals with sustainable alternatives is necessary to mitigate the effects of climate change and also to counteract diminishing fossil resources. Acetogenic microorganisms such as Clostridium spp. are promising sources of fuels and basic chemical precursors because they efficiently utilize CO and CO2 as carbon source. However the conversion into high titers of butanol and hexanol is challenging. RESULTS: Using a metabolic engineering approach we transferred a 17.9-kb gene cluster via conjugation, containing 13 genes from C. kluyveri and C. acetobutylicum for butanol and hexanol biosynthesis, into C. ljungdahlii. Plasmid-based expression resulted in 1075 mg L-1 butanol and 133 mg L-1 hexanol from fructose in complex medium, and 174 mg L-1 butanol and 15 mg L-1 hexanol from gaseous substrate (20% CO2 and 80% H2) in minimal medium. Product formation was increased by the genomic integration of the heterologous gene cluster. We confirmed the expression of all 13 enzymes by targeted proteomics and identified potential rate-limiting steps. Then, we removed the first-round selection marker using CRISPR/Cas9 and integrated an additional 7.8 kb gene cluster comprising 6 genes from C. carboxidivorans. This led to a significant increase in the hexanol titer (251 mg L-1) at the expense of butanol (158 mg L-1), when grown on CO2 and H2 in serum bottles. Fermentation of this strain at 2-L scale produced 109 mg L-1 butanol and 393 mg L-1 hexanol. CONCLUSIONS: We thus confirmed the function of the butanol/hexanol biosynthesis genes and achieved hexanol biosynthesis in the syngas-fermenting species C. ljungdahlii for the first time, reaching the levels produced naturally by C. carboxidivorans. The genomic integration strain produced hexanol without selection and is therefore suitable for continuous fermentation processes.


Assuntos
Butanóis , Engenharia Metabólica , 1-Butanol/metabolismo , Butanóis/metabolismo , Dióxido de Carbono/metabolismo , Clostridium/genética , Clostridium/metabolismo , Fermentação , Hexanóis/metabolismo , Engenharia Metabólica/métodos
10.
Environ Sci Pollut Res Int ; 29(32): 47988-48019, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35562606

RESUMO

A significant concern of our fuel-dependent era is the unceasing exhaustion of petroleum fuel supplies. In parallel to this, environmental issues such as the greenhouse effect, change in global climate, and increasing global temperature must be addressed on a priority basis. Biobutanol, which has fuel characteristics comparable to gasoline, has attracted global attention as a viable green fuel alternative among the many biofuel alternatives. Renewable biomass could be used for the sustainable production of biobutanol by the acetone-butanol-ethanol (ABE) pathway. Non-extinguishable resources, such as algal and lignocellulosic biomass, and starch are some of the most commonly used feedstock for fermentative production of biobutanol, and each has its particular set of advantages. Clostridium, a gram-positive endospore-forming bacterium that can produce a range of compounds, along with n-butanol is traditionally known for its biobutanol production capabilities. Clostridium fermentation produces biobased n-butanol through ABE fermentation. However, low butanol titer, a lack of suitable feedstock, and product inhibition are the primary difficulties in biobutanol synthesis. Critical issues that are essential for sustainable production of biobutanol include (i) developing high butanol titer producing strains utilizing genetic and metabolic engineering approaches, (ii) renewable biomass that could be used for biobutanol production at a larger scale, and (iii) addressing the limits of traditional batch fermentation by integrated bioprocessing technologies with effective product recovery procedures that have increased the efficiency of biobutanol synthesis. Our paper reviews the current progress in all three aspects of butanol production and presents recent data on current practices in fermentative biobutanol production technology.


Assuntos
1-Butanol , Biodiversidade , Biocombustíveis , Butanóis , Clostridium/metabolismo , Fermentação , Temperatura
11.
Bioresour Technol ; 353: 127078, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35395367

RESUMO

The present study aimed to enzymatic deinking of waste papers and to valorize the effluent for biobutanol production. Application of fungal enzymatic cocktail (cellulase, amylase, xylanase, pectinase, lipase, and ligninase) on office used paper, newspaper, and ballpen written paper leading to improvement in brightness (84.91, 72.51, 76.69 % ISO), InKd (82.89, 68.95, 76.49%), κ-number (12.9, 13.6, and 13.1), opacity (27.91, 30.07, and 2.85%), tensile strength (49.24, 45.31, and 46.98 Nm/g), respectively and indices were consistent with chemical treated pulps. The quality of effluent generated during enzymatic deinking in respect to BOD and COD level was eco-friendlier than the chemical process. The enzyme-treated effluent was employed as supporting substrate for butanol (18.4 g/l) production by Clostridium acetobutylicum ATCC824. Material balance and life cycle assessment of the whole processes were evaluated to validate its industrial and environmental relevance.


Assuntos
Celulase , Clostridium acetobutylicum , 1-Butanol , Butanóis , Tinta , Papel
12.
Bioresour Technol ; 353: 127138, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35405210

RESUMO

In this study, continuous cultivations of C.carboxidivorans to study heterotrophic and mixotrophic conversion of glucose and H2, CO2, and CO were established. Glucose fermentations at pH 6 showed a high ratio of alcohol-to-acid production of 2.79 mol mol-1. While H2 or CO2 were not utilized together with glucose, CO feeding drastically increased the combined alcohol titer to 9.1 g l-1. Specifically, CO enhanced acetate (1.9-fold) and ethanol (1.7-fold) production and triggered chain elongation to butanol (1.5-fold) production but did not change the alcohol:acid ratio. Flux balance analysis showed that CO served both as a carbon and energy source, and CO mixotrophy displayed a carbon and energy efficiency of 45 and 77%, respectively. This study expands the knowledge on physiology and metabolism of C.carboxidivorans and can serve as the starting point for rational engineering and process intensification to establish efficient production of alcohols and acids from carbon waste.


Assuntos
Butanóis , Monóxido de Carbono , 1-Butanol/metabolismo , Butanóis/metabolismo , Dióxido de Carbono/metabolismo , Monóxido de Carbono/metabolismo , Clostridium/metabolismo , Etanol/metabolismo , Fermentação , Glucose/metabolismo
14.
Microbiol Spectr ; 10(2): e0228821, 2022 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-35412381

RESUMO

Transcription initiation is a tightly regulated process that is crucial for many aspects of prokaryotic physiology. High-throughput transcription start site (TSS) mapping can shed light on global and local regulation of transcription initiation, which in turn may help us understand and predict microbial behavior. In this study, we used Capp-Switch sequencing to determine the TSS positions in the genomes of three model solventogenic clostridia: Clostridium acetobutylicum ATCC 824, C. beijerinckii DSM 6423, and C. beijerinckii NCIMB 8052. We first refined the approach by implementing a normalization pipeline accounting for gene expression, yielding a total of 12,114 mapped TSSs across the species. We further compared the distributions of these sites in the three strains. Results indicated similar distribution patterns at the genome scale, but also some sharp differences, such as for the butyryl-CoA synthesis operon, particularly when comparing C. acetobutylicum to the C. beijerinckii strains. Lastly, we found that promoter structure is generally poorly conserved between C. acetobutylicum and C. beijerinckii. A few conserved promoters across species are discussed, showing interesting examples of how TSS determination and comparison can improve our understanding of gene expression regulation at the transcript level. IMPORTANCE Solventogenic clostridia have been employed in industry for more than a century, initially being used in the acetone-butanol-ethanol (ABE) fermentation process for acetone and butanol production. Interest in these bacteria has recently increased in the context of green chemistry and sustainable development. However, our current understanding of their genomes and physiology limits their optimal use as industrial solvent production platforms. The gene regulatory mechanisms of solventogenesis are still only partly understood, impeding efforts to increase rates and yields. Genome-wide mapping of transcription start sites (TSSs) for three model solventogenic Clostridium strains is an important step toward understanding mechanisms of gene regulation in these industrially important bacteria.


Assuntos
Acetona , Clostridium acetobutylicum , Acetona/metabolismo , Bactérias Anaeróbias , Butanóis/metabolismo , Clostridium/genética , Clostridium/metabolismo , Clostridium acetobutylicum/genética , Clostridium acetobutylicum/metabolismo , Fermentação
15.
Chem Commun (Camb) ; 58(38): 5793-5796, 2022 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-35466974

RESUMO

Enzyme-free isothermal amplification reactions for nucleic acid analysis usually take several hours to obtain sufficient detection sensitivity, which limits their practical applications. Herein, we report a butanol dehydration-based method to greatly improve both the efficiency and the sensitivity of nucleic acid detections by three types of enzyme-free isothermal amplification reactions. The reaction time has been shortened from 3 h to 5-20 min with higher sensitivities. Especially in the DNAzyme-based amplification, the detection limit can be lowered over 16 000-fold to 3 × 10-17 mol L-1 in 2 h compared to the normal 3 h-reaction. We demonstrate that the high amplification efficiencies are attributed to the greatly accelerated reaction rates in the extremely concentrated reaction solutions caused by the butanol dehydration. This approach enhances the potential of applications of isothermal amplification reactions in clinical rapid tests, nanostructure synthesis, etc. and is promising to expand to other types of chemical reactions.


Assuntos
Butanóis , DNA Catalítico , Desidratação/diagnóstico , Humanos , Técnicas de Amplificação de Ácido Nucleico/métodos
16.
J Environ Manage ; 310: 114772, 2022 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-35228167

RESUMO

Butyl butyrate (BB) derived from bio-renewable resources is the most promising jet fuel blend. This review highlights essential properties of jet fuel, including calorific value, kinematic viscosity, freezing point, flash point, auto-ignition temperature, and density to compare with different bio-renewable chemicals, which are compatible to be blended with the jet fuel. A detailed discussion follows on the importance of intermediate formation, reaction mechanism, and catalyst properties that are critical towards the production of bio-renewable resource-derived BB. BB is primarily produced via the esterification of butyric acid (BA) in butanol (BuOH) with or without using a catalyst. The corresponding reactions are carried out in both homogeneous and heterogeneous phases, provided it has acidic properties. Thus, a wide range of acidic catalysts such as [HSO3-pmim] HSO4 ionic liquids, heteropolyacid, methanesulfonic acid, Dowex 50 Wx8-400 resins, and sulfonated char causes up to 98%, 97.9%, 93.2%, 95.3%, and 90% of BB yield, respectively are critically reviewed. Moreover, reaction mechanism, product, and by-product formation that primarily dictate the BB yield and selectivity have been comprehensively reviewed. In addition, catalytic and mechanistic insights on BB production from other bio-renewable resources such as butyric anhydride, butyraldehyde, dibutyl ether, and methanol have been discussed in this review.


Assuntos
Biocombustíveis , Butiratos , Butanóis , Esterificação
17.
Biochem Soc Trans ; 50(2): 867-876, 2022 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-35356968

RESUMO

Biobutanol is gaining much attention as a potential biofuel due to its superior properties over ethanol. Butanol has been naturally produced via acetone-butanol-ethanol (ABE) fermentation by many Clostridium species, which are not very user-friendly bacteria. Therefore, to improve butanol titers and yield, various butanol synthesis pathways have been engineered in Escherichia coli, a much more robust and convenient host than Clostridium species. This review mainly focuses on the biosynthesis of n-butanol in engineered E. coli with an emphasis on efficient enzymes for butanol production in E. coli, butanol competing pathways, and genome engineering of E. coli for butanol production. In addition, the use of alternate strategies for butanol biosynthesis/enhancement, alternate substrates for the low cost of butanol production, and genetic improvement for butanol tolerance in E. coli have also been discussed.


Assuntos
1-Butanol , Butanóis , 1-Butanol/metabolismo , Butanóis/metabolismo , Clostridium/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Etanol/metabolismo , Fermentação , Engenharia Metabólica
18.
Neurochem Res ; 47(6): 1692-1706, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35230647

RESUMO

Since sleep is a key homeostatic phenomenon of the body, therefore understanding the complex etiology of the neurological outcome of sleep deprivation (SD) such as anxiety, depression, cognitive dysfunctions, and their management is of utmost importance. The findings of the current study encompass the neurobehavioral as well as hormonal, and neuroinflammatory changes in serum and hypothalamus region of the brain as an outcome of acute SD and their amelioration by pre-treatment with butanol extract of Tinospora cordifolia. SD group animals showed anxiety-like behavior as evident from Elevated Plus Maze data and higher serum cortisol levels, whereas, pre-treatment with B-TCE showed anxiolytic activity and also reduced cortisol levels which was corroborated by an increase in leptin and insulin levels. Further, SD induced elevation of serum pro-inflammatory cytokines IL-6, TNF-α, IL-1ß, and MCP-1 and subsequent activation of astroglial cells in the hypothalamus was suppressed in B-TCE pre-treated animals. The current findings suggest that besides the cortical structures, hypothalamus region's synaptic plasticity and cell survival are adversely impacted by acute SD. Further active ingredients present in B-TCE may be useful for the management of SD-induced anxiety, systemic inflammation, and neuroinflammation by targeting hypothalamic BDNF-TrkB/PI3K-Akt pathways.


Assuntos
Tinospora , Animais , Ansiedade , Butanóis , Sobrevivência Celular , Hidrocortisona , Hipotálamo/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Privação do Sono/complicações , Privação do Sono/metabolismo , Tinospora/química , Tinospora/metabolismo
19.
Chemosphere ; 299: 134425, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35351479

RESUMO

Biofuels, such as ethanol and butanol, obtained from carbon monoxide-rich gas or syngas bioconversion (solventogenesis) are an attractive alternative to traditional fermentation processes with merits of no competition with food production and sustainability. However, there is a lack of comprehensive understanding of some key process parameters and mechanisms enhancing solventogenesis during the fermentation process. This review provides an overview of the current state of the art of the main influencing factors during the syngas fermentation process catalyzed by acetogenic species as well as undefined mixed cultures. The role of syngas pressure, syngas components, fermentation pH, temperature, trace metals, organic compounds and additional materials is overviewed. As a so far hardly considered approach, thermodynamic calculations of the Gibbs free energy of CO conversion to acetic acid, ethanol, butyric acid and butanol under different CO pressures and pH at 25, 33 and 55 °C are also addressed and reviewed. Strategies for enhancing mass transfer and longer carbon chain solvent production are considered as well.


Assuntos
Reatores Biológicos , Clostridium , 1-Butanol , Ácido Acético , Butanóis , Monóxido de Carbono , Etanol , Fermentação , Termodinâmica
20.
Regul Toxicol Pharmacol ; 131: 105157, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35292310

RESUMO

Chemical leukoderma is an acquired depigmentation of the skin caused by repeated exposure to specific agents damaging to epidermal melanocytes. Case reports of chemical leukoderma have been associated with some consumer products. To date, there are no well-accepted approaches for evaluating and minimizing this risk. To this end, a framework is presented that evaluates the physical and chemical characteristics of compounds associated with chemical leukoderma and employs structure-activity relationship (SAR) read-across and predictive metabolism tools to determine whether a compound is at increased risk of evoking chemical leukoderma. In addition to in silico approaches, the testing strategy includes in chemico quinone formation and in vitro melanocyte cytotoxicity assays to dimension the risk as part of an overall weight of evidence approach to risk assessment. Cosmetic ingredients raspberry ketone, undecylenoyl phenylalanine, tocopheryl succinate, p-coumaric acid, resveratrol, resveratrol dimethyl ether, sucrose dilaurate, tranexamic acid, niacinamide and caffeic acid are evaluated in this framework and compared to positive controls rhododendrol and hydroquinone. Overall, this framework is considered an important step toward mitigating the risk of chemical leukoderma for compounds used in consumer products.


Assuntos
Hipopigmentação , Butanóis , Epiderme/metabolismo , Humanos , Hipopigmentação/induzido quimicamente , Hipopigmentação/metabolismo , Melanócitos/metabolismo , Resveratrol/metabolismo , Pele/metabolismo
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