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1.
J Fish Dis ; : e13991, 2024 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-38943443

RESUMO

Alternatives to conventional chemical treatments for parasitic diseases in fish are needed. Microalgal-sourced fatty acid ethyl esters (FAEEs) have shown an antiparasitic effect against Gyrodactylus turnbulli infection in guppies. Here, we tested a range of commercial FAEEs of various carbon chain lengths and unsaturation levels against two fish parasites. Guppies and barramundi infected with G. turnbulli and Trichodina sp., respectively, were used. The most effective FAEE, after excluding those toxic to fish, was ethyl laurate (12:0). For both parasites, the LD50 was 18.75 µM within 250 min of incubation. Ethyl eicosapentaenoate (20:5n3) was the next most effective FAEE against G. turnbulli, and dihomo-γ-linolenic acid ethyl ester (20:3n6) and ethyl α-linolenate (18:3n3) were the next most effective against Trichodina sp. In addition, FAEEs prepared from the microalga Phaeodactylum tricornutum residue, after fucoxanthin extraction, were examined against Trichodina sp. infection in barramundi for the first time. LD85 and LD100 was achieved at 2.5 and 5 µL mL-1 of the FAEE preparation, respectively. In vivo, immersion of infected barramundi in 1.25 µL mL-1 of this preparation for 24 h reduced infection prevalence from 100% to 53% and was non-toxic to fish.

2.
FEMS Yeast Res ; 17(7)2017 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-28961899

RESUMO

Fatty acids and fatty acid derivatives are important biorenewable products, as well as precursors for further transformation via chemical catalysis. This minireview focuses on recent advances in increasing the production of fatty acids and derived products in the yeast Saccharomyces cerevisiae. The engineering of upstream pathways to increase levels of the required precursors, fatty acid synthase systems to increase expression and to modify chain length, and downstream pathways to produce free fatty acids, fatty acid ethyl esters, fatty alcohols and alkanes are highlighted, and current challenges are discussed.


Assuntos
Ácidos Graxos/biossíntese , Engenharia Metabólica , Saccharomyces cerevisiae/metabolismo , Ácidos Graxos/genética , Ácidos Graxos/metabolismo , Saccharomyces cerevisiae/genética
3.
Bioprocess Biosyst Eng ; 40(5): 723-730, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28210816

RESUMO

In situ transesterification of wet microalgae is a promising, simplified alternative biodiesel production process that replaces multiple operations of cell drying, extraction, and transesterification reaction. This study addresses enhanced biodiesel production from Nannochloropsis gaditana at elevated temperatures. Compared with the previously reported in situ transesterification process of conducting the reaction at a temperature ranging from 95 to 125 °C, the present work employs higher temperatures of at least 150 °C. This relatively harsh condition allows much less acid catalyst with or without co-solvent to be used during this single extraction-conversion process. Without any co-solvent, 0.58% (v/v) of H2SO4 in the reaction medium can achieve 90 wt% of the total lipid conversion to biodiesel at 170 °C when the moisture content of wet algal paste is 80 wt%. Here, the effects of temperature, acid catalyst, and co-solvent on the FAEE yield and specification were scrutinized, and the reaction kinetic was investigated to understand the solvothermal in situ transesterification reaction at the high temperature. Having a biphasic system (water/chloroform) during the reaction also helped to meet biodiesel quality standard EN 14214, as Na+, K+, Ca2+, Mg2+ cations and phosphorus were detected only below 5 ppm. With highlights on the economic feasibility, wet in situ transesterification at the high temperature can contribute to sustainable production of biodiesel from microalgae by reducing the chemical input and relieve the burden of extensive post purification process, therefore a step towards green process.


Assuntos
Biocombustíveis , Temperatura Alta , Lipídeos/química , Estramenópilas/química , Esterificação , Ácidos Sulfúricos/química
4.
IUBMB Life ; 68(12): 916-923, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27714979

RESUMO

Ethanol is a widely used psychoactive drug whose chronic abuse is associated with organ dysfunction and disease. Although the prevalent metabolic fate of ethanol in the human body is oxidation a smaller fraction undergoes nonoxidative metabolism yielding ethyl glucuronide, ethyl sulfate, phosphatidylethanol and fatty acid ethyl esters. Nonoxidative ethanol metabolites persist in tissues and body fluids for much longer than ethanol itself and represent biomarkers for the assessment of ethanol intake in clinical and forensic settings. Of note, the nonoxidative reaction of ethanol with phospholipids and fatty acids yields bioactive compounds that affect cellular signaling pathways and organelle function and may contribute to ethanol toxicity. Thus, despite low quantitative contributions of nonoxidative pathways to overall ethanol metabolism the resultant ethanol metabolites have important biological implications. In this review we summarize the current knowledge about the enzymatic formation of nonoxidative ethanol metabolites in humans and discuss the implications of nonoxidative ethanol metabolites as biomarkers of ethanol intake and mediators of ethanol toxicity. © 2016 IUBMB Life, 68(12):916-923, 2016.


Assuntos
Consumo de Bebidas Alcoólicas/metabolismo , Etanol/metabolismo , Ácidos Graxos/metabolismo , Glicerofosfolipídeos/metabolismo , Animais , Biomarcadores/metabolismo , Glucuronatos/metabolismo , Humanos , Inativação Metabólica , Oxirredução , Ésteres do Ácido Sulfúrico/metabolismo , Distribuição Tecidual
5.
FEMS Yeast Res ; 16(1): fov105, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26590613

RESUMO

Saccharomyces cerevisiae has previously been engineered to become a cell factory for the production of fatty acid ethyl esters (FAEEs), molecules suitable for crude diesel replacement. To find new metabolic engineering targets for the improvement of FAEE cell factories, three different FAEE-producing strains of S. cerevisiae, constructed previously, were compared and characterized by quantification of key fluxes and genome-wide transcription analysis. From both the physiological and the transcriptional data, it was indicated that strain CB2I20, with high expression of a heterologous wax ester synthase gene (ws2) and strain BdJ15, containing disruptions of genes DGA1, LRO1, ARE1, ARE2 and POX1, which prevent the conversion of acyl-CoA to sterol esters, triacylglycerides and the degradation to acetyl-CoA, triggered oxidative stress that consequently influenced cellular growth. In the latter strain, stress was possibly triggered by disabling the buffering capacity of lipid droplets in encapsulating toxic fatty acids such as oleic acid. Additionally, it was indicated that there was an increased demand for NADPH required for the reduction steps in fatty acid biosynthesis. In conclusion, our analysis clearly shows that engineering of fatty acid biosynthesis results in transcriptional reprogramming and has a significant effect on overall cellular metabolism.


Assuntos
Ésteres/metabolismo , Ácidos Graxos/metabolismo , Perfilação da Expressão Gênica , Engenharia Metabólica , Análise do Fluxo Metabólico , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Aciltransferases/metabolismo , Biocombustíveis , NADP/metabolismo
6.
Anal Bioanal Chem ; 408(13): 3503-9, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26968564

RESUMO

The forensic utility of fatty acid ethyl esters (FAEEs) in dried blood spots (DBS) as short-term confirmatory markers for ethanol intake was examined. An LC-MS/MS method for the determination of FAEEs in DBS was developed and validated to investigate FAEE formation and elimination in a drinking study, whereby eight subjects ingested 0.66-0.84 g/kg alcohol to reach blood alcohol concentrations (BAC) of 0.8 g/kg. Blood was taken every 1.5-2 h, BAC was determined, and dried blood spots were prepared, with 50 µL of blood, for the determination of FAEEs. Lower limits of quantitation (LLOQ) were between 15 and 37 ng/mL for the four major FAEEs. Validation data are presented in detail. In the drinking study, ethyl palmitate and ethyl oleate proved to be the two most suitable markers for FAEE determination. Maximum FAEE concentrations were reached in samples taken 2 or 4 h after the start of drinking. The following mean peak concentrations (c̅(max)) were reached: ethyl myristate 14 ± 4 ng/mL, ethyl palmitate 144 ± 35 ng/mL, ethyl oleate 125 ± 55 ng/mL, ethyl stearate 71 ± 21 ng/mL, total FAEEs 344 ± 91 ng/mL. Detectability of FAEEs was found to be on the same time scale as BAC. In liquid blood samples containing ethanol, FAEE concentrations increase post-sampling. This study shows that the use of DBS fixation prevents additional FAEE formation in blood samples containing ethanol. Positive FAEE results obtained by DBS analysis can be used as evidence for the presence of ethanol in the original blood sample.


Assuntos
Consumo de Bebidas Alcoólicas , Biomarcadores/sangue , Cromatografia Líquida/métodos , Etanol/administração & dosagem , Ácidos Graxos/sangue , Espectrometria de Massas em Tandem/métodos , Adulto , Ésteres/química , Etanol/sangue , Ácidos Graxos/química , Feminino , Humanos , Limite de Detecção , Masculino , Adulto Jovem
7.
Metab Eng ; 32: 195-206, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26460058

RESUMO

Microbially produced lipids like triacylglycerols or fatty acid ethyl esters are currently of great interest as fuel replacements or other industrially relevant compounds. They can even be produced by non-oleaginous microbes, like Escherichia coli, upon metabolic engineering. However, there is still much room for improvement regarding the yield for a competitive microbial production of lipids or biofuels. We genetically engineered E. coli by expressing fadD, fadR, pgpB, plsB and 'tesA in combination with atfA from Acinetobacter baylyi. A total fatty acid contents of up to 16% (w/w) was obtained on complex media, corresponding to approximately 9% (w/w) triacylglycerols and representing the highest titers of fatty acids and triacylglycerols obtained in E. coli under comparable cultivation conditions, so far. To evaluate further possibilities for an optimization of lipid production, ten promising bacterial wax ester synthase/acyl-Coenzyme A:diacylglycerol acyltransferases were tested and compared. While highest triacylglycerol storage was achieved with AtfA, the mutated variant AtfA-G355I turned out to be most suitable for fatty acid ethyl ester biosynthesis and enabled an accumulation of approx. 500 mg/L without external ethanol supplementation.


Assuntos
Aciltransferases/genética , Aciltransferases/metabolismo , Escherichia coli/enzimologia , Escherichia coli/genética , Lipídeos/biossíntese , Engenharia Metabólica/métodos , Acinetobacter/genética , Acinetobacter/metabolismo , Biocombustíveis , Diacilglicerol O-Aciltransferase/genética , Diacilglicerol O-Aciltransferase/metabolismo , Etanol/metabolismo , Ácidos Graxos/metabolismo , Plasmídeos/genética , Triglicerídeos/metabolismo
8.
Yeast ; 31(12): 463-74, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25308280

RESUMO

Fatty acid ethyl esters are secondary metabolites that are produced during microbial fermentation, in fruiting plants and in higher organisms during ethanol stress. In particular, volatile medium-chain fatty acid ethyl esters are important flavour compounds that impart desirable fruit aromas to fermented beverages, including beer and wine. The biochemical synthesis of medium-chain fatty acid ethyl esters is poorly understood but likely involves acyl-CoA:ethanol O-acyltransferases. Here, we characterize the enzyme ethanol hexanoyl transferase 1 (Eht1) from the brewer's yeast Saccharomyces cerevisiae. Full-length Eht1 was successfully overexpressed from a recombinant yeast plasmid and purified at the milligram scale after detergent solubilization of sedimenting membranes. Recombinant Eht1 was functional as an acyltransferase and, unexpectedly, was optimally active toward octanoyl-CoA, with k(cat) = 0.28 ± 0.02/s and K(M) = 1.9 ± 0.6 µm. Eht1 was also revealed to be active as a thioesterase but was not able to hydrolyse p-nitrophenyl acyl esters, in contrast to the findings of a previous study. Low-resolution structural data and site-directed mutagenesis provide experimental support for a predicted α/ß-hydrolase domain featuring a Ser-Asp-His catalytic triad. The S. cerevisiae gene YBR177C/EHT1 should thus be reannotated as coding for an octanoyl-CoA:ethanol acyltransferase that can also function as a thioesterase.


Assuntos
Acil Coenzima A/metabolismo , Aciltransferases/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/enzimologia , Tioléster Hidrolases/metabolismo , Análise Mutacional de DNA , Expressão Gênica , Cinética , Mutagênese Sítio-Dirigida , Conformação Proteica , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo
9.
Biotechnol Bioeng ; 111(11): 2200-8, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24895195

RESUMO

Biodiesels in the form of fatty acyl ethyl esters (FAEEs) are a promising next generation biofuel due to their chemical properties and compatibility with existing infrastructure. It has recently been shown that expression of a bacterial acyl-transferase in the established industrial workhorse Saccharomyces cerevisiae can lead to production of FAEEs by condensation of fatty acyl-CoAs and ethanol. In contrast to recent strategies to produce FAEEs in S. cerevisiae through manipulation of de novo fatty acid biosynthesis or a series of arduous genetic manipulations, we introduced a novel genetic background, which is comparable in titer to previous reports with a fraction of the genetic disruption by aiming at increasing the fatty acyl-CoA pools. In addition, we combined metabolic engineering with modification of culture conditions to produce a maximum titer of over 25 mg/L FAEEs, a 40% improvement over previous reports and a 17-fold improvement over our initial characterizations. Biotechnol. Bioeng. 2014;111: 2200-2208. © 2014 Wiley Periodicals, Inc.


Assuntos
Meios de Cultura/química , Ésteres/metabolismo , Ácidos Graxos/metabolismo , Engenharia Metabólica/métodos , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/metabolismo , Biocombustíveis , Saccharomyces cerevisiae/genética
10.
Biotechnol J ; 19(1): e2300350, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38135869

RESUMO

A novel approach for in situ transesterification, extraction, separation, and purification of fatty acid ethyl esters (FAEE) for biodiesel and docosahexaenoic acid (DHA) from Thraustochytrid biomass has been developed. The downstream processing of Thraustochytrids oil necessitates optimization, considering the higher content of polyunsaturated fatty acids (PUFA). While two-step methods are commonly employed for extracting and transesterifying oil from oleaginous microbes, this may result in oxidation/epoxidation of omega-3 oil due to prolonged exposure to heat and oxygen. To address this issue, a rapid single-step method was devised for in situ transesterification of Thraustochytrid oil. Through further process optimization, a 50% reduction in solvent requirement was achieved without significantly impacting fatty acid recovery or composition. Scale-up studies in a 4 L reactor demonstrated complete FAEE recovery (99.98% of total oil) from biomass, concurrently enhancing DHA yield from 16% to nearly 22%. The decolorization of FAEE oil with fuller's earth effectively removed impurities such as pigments, secondary metabolites, and waxes, resulting in a clear, shiny appearance. High-performance liquid chromatography (HPLC) analysis indicated that the eluted DHA was over 94.5% pure, as corroborated by GC-FID analysis.


Assuntos
Ácidos Docosa-Hexaenoicos , Ácidos Graxos Ômega-3 , Ácidos Docosa-Hexaenoicos/química , Biocombustíveis , Biomassa , Ácidos Graxos/química , Ácidos Graxos Ômega-3/química , Ésteres/metabolismo
11.
Front Bioeng Biotechnol ; 12: 1355009, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38390361

RESUMO

Recently, enzymatic method has been used to prepare biodiesel using various oils. But the high acid value of the biodiesel product using enzyme as a catalyst has been one issue. In this work, an attempt to reduce the acid value of fatty acid ethyl ester (FAEE) product to satisfy the specified requirement (AV ≤ 0.5 mgKOH/g), a complex enzyme-catalyzed method was used for the ethanolysis of Semen Abutili seed oil (SASO) (AV = 5.5 ± 0.3 mgKOH/g). The effects of various variables (constituents of complex enzyme, type and addition of water removal agent, time, temperature, enzyme addition load, substrate ratio) on the enzymatic reaction were investigated. The optimal reaction conditions were: 1% addition of liquid lipase Eversa® Transform 2.0% and 0.8% of enzyme dry powder CALB, reaction temperature 35°C, alcohol-oil ratio 9:1 (mol/mol), 0.8 g/g of 4A-MS and reaction time 24 h. Under the optimal reaction conditions, the FAEE yield was 90.8% ± 1.5% and its acid value was decreased from 12.0 ± 0.2 mgKOH/g to 0.39 ± 0.10 mgKOH/g. In further evaluating the feasibility of preparing FAEE from SASO, the FAEE products obtained under the optimal reaction conditions were purified and evaluated with reference to the ASTM D6751 standard for the main physicochemical indexes. The results obtained were in accordance with the requirements except for the oxidative stability.

12.
Food Chem ; 463(Pt 1): 141171, 2024 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-39260168

RESUMO

This study aimed to authenticate re-esterified triacylglycerol (rTG)-type omega-3 oils prone to adulteration with fatty acid ethyl ester (FAEE)-type oils via hierarchical cluster analysis (HCA) and principal component analysis (PCA) of their lipid profiles. A total of 104 rTG-type omega-3 oil samples, consisting of seven authentic (two commercial and five laboratory-made), 60 adulterated, and 37 unauthenticated commercial samples, were analyzed for their acylglycerol, FAEE, and total EPA/DHA contents. Type 1 authentic samples contained higher triacylglycerols (TG) (63.0-86.3 wt%), lower diacylglycerols (DG) (8.1-31.5 wt%), and no FAEE compared to type 2 authentic samples (36.9-62.1 wt% TG, 9.4-36.9 wt% DG, and 14.9-27.3 wt% FAEE). HCA and PCA differentiated authentic samples from adulterated samples, although type 2 samples were closer to adulterated samples. Both analyses showed that 30/37 commercial samples exhibited higher similarity in lipid profiles to authentic samples than to adulterated samples, indicating their potential for authentication.

13.
Foods ; 12(16)2023 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-37628086

RESUMO

The storage process of Baijiu is an integral part of its production (the quality undergoes substantial changes during the aging process of Baijiu). As the storage time extends, the flavor compounds in Baijiu tend to undergo coordinated transformation, thereby enhancing the quality of Baijiu. Among them, long-chain fatty acid ethyl esters (LCFAEEs) were widely distributed in Baijiu and have been shown to have potential contributions to the quality of Baijiu. However, the current research on LCFAEEs in Baijiu predominantly focuses on the olfactory sensation aspect, while there is a lack of systematic investigation into their influence on taste and evaluation after drinking Baijiu during the aging process. In light of this, the present study investigates the distribution of LCFAEEs in Baijiu over different years. We have combined modern flavor sensory analysis with multivariate chemometrics to comprehensively and objectively explore the influence of LCFAEEs on Baijiu quality. The results demonstrate a significant positive correlation between the concentration of LCFAEEs and the fruity aroma (p < 0.05, r = 0.755) as well as the aged aroma (p < 0.05, r = 0.833) of Baijiu within a specific range; they can effectively reduce the off-flavors and spicy sensation of Baijiu. Furthermore, additional experiments utilizing a single variable suggest that LCFAEEs were crucial factors influencing the flavor of Baijiu, with Ethyl Palmitate (EP) being the most notable LCFAEE that merits further systematic investigation.

14.
Food Chem X ; 19: 100760, 2023 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-37780337

RESUMO

Breast milk plays a crucial role in the taste development of infants, which cannot be replicated by other mammalian milk or formulas. This study aimed to identify and characterize the flavor substances in 15 different types of milk and analyze the differences among them. The results showed that human milk contained high levels of esters, particularly fatty acid ethyl esters, which contribute to its unique flavor. The four substances that had the highest flavor contribution in all species were identified as 2,3-butanedione, trimethylamine, isophorone, and acetaldehyde. Furthermore, the analysis of differences revealed that thermal-oxidation of lipids could explain the variation between human milk and other species in terms of flavor compounds. The key differential flavor compounds identified in milk from all species were trimethylamine, propanal, 1-pentanol, pyridine 2-methyl, and 2-butanone. These findings can potentially aid in developing formulas that better meet the taste needs of infants.

15.
Foods ; 12(6)2023 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-36981194

RESUMO

Long-chain fatty acid ethyl ester (LCFAEEs) is colorless and has a weak wax and cream aroma. It can be used as an intermediate for the synthesis of emulsifiers, and stabilizers and be applied in the production of flavor essence. It is also an important trace component in Baijiu and is attributed to making a contribution to the quality of Baijiu, but its distribution in Baijiu has not been clear, and its influence mechanisms on Baijiu quality have not been systematically studied. Therefore, the distribution of LCFAEEs for Baijiu in different years (2014, 2015, 2018, and 2022), different grades (premium, excellent, and level 1; note: here Baijiu grade classification was based on Chinese standard (GB/T 10781) and enterprise classification standard), and different sun exposure times (0, 6, 12, 20, 30, and 50 days) was uncovered. Thus, in this study, the effect of LCFAEEs on the quality of Baijiu was comprehensively and objectively proven by combining modern flavor sensomics and multicomponent chemometrics. The results showed that with the increase in Baijiu storage time, the concentration of LCFAEEs increased significantly in Baijiu (4.38-196.95 mg/L, p < 0.05). The concentration of LCFAEEs in level 1 Baijiu was significantly higher than that in excellent and premium Baijiu (the concentration ranges of ET, EP, EO, E9, E912, and E91215 were: 0.27-2.31 mg/L, 0.75-47.41 mg/L, 0.93-1.80 mg/L, 0.98-12.87 mg/L, 1.01-27.08 mg/L, and 1.00-1.75 mg/L, respectively, p < 0.05). With the increase in sun exposure time, the concentration of LCFAEEs in the Baijiu first increased significantly and then decreased significantly (4.38-5.95 mg/L, p < 0.05). As the flavor sensomics showed, the concentrations of LCFAEEs in Baijiu bodies were significantly correlated with the Baijiu taste sense (inlet taste, aroma sensation in the mouth), as well as with the evaluation after drinking (maintaining taste) (p < 0.05, r > 0.7). Based on the above, LCFAEEs are critical factors for Baijiu flavor thus, it is essential to explore a suitable concentration of LCFAEEs in Baijiu to make Baijiu's quality more ideal.

16.
J Oleo Sci ; 71(7): 1051-1062, 2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35691836

RESUMO

Fatty acid ethyl esters (FAEEs) derived from vegetable oils and ethanol are promising bio-based chemicals for various applications such as biofuel, monomers for polyesters, and fine chemicals. However, the limited conversion and yield are obtained in the conventional methods due to low boiling point of ethanol that thus requires conducting the reaction at low temperature. This work demonstrates high yield of FAEEs from soybean, rice bran and palm oil with ethanol by performing the transesterification at high temperatures of 150-200°C by using CaO catalyst in a high pressure reactor. The results demonstrate the complete reaction for all vegetable oils with low ethanol to oil molar ratio of 6:1 and 1 wt.% CaO catalyst. Higher reaction temperature results in faster reaction while keeping high conversion of ≥ 99.0%. The unsaturated components in FAEE products are consistent with their original fatty acid chain. Moreover, the high conversion can be achieved even in the reaction conducted with low ethanol to oil molar ratio of 4.5:1 and 0.5 wt.% CaO catalyst at 180 °C in the palm oil transesterification. The catalyst can be reused for at least 3 times with the conversion higher than 94.0%. In addition, the activation energy (Ea), enthalpy of activation (ΔH‡), entropy of activation (ΔS‡) and Gibbs free energy of activation (ΔG‡) are also obtained.


Assuntos
Etanol , Óleos de Plantas , Biocombustíveis , Catálise , Esterificação , Ésteres , Ácidos Graxos , Óleo de Palmeira
17.
Front Microbiol ; 13: 1107104, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36713181

RESUMO

Fatty acid ethyl esters are important flavor chemicals in strong-flavor Baijiu. Monascus purpureus YJX-8 is recognized as an important microorganism for ester synthesis in the fermentation process. Enzyme LIP05 from YJX-8 can efficiently catalyze the synthesis of fatty acid ethyl esters under aqueous phase, but the key catalytic sites affecting esterification were unclear. The present work combined homology modeling, molecular dynamics simulation, molecular docking and site-directed mutation to analyze the catalytic mechanism of LIP05. Protein structure modeling indicated LIP05 belonged to α/ß fold hydrolase, contained a lid domain and a core catalytic pocket with conserved catalytic triad Ser150-His215-Asp202, and the oxyanion hole composed of Gly73 and Thr74. Ile30 and Leu37 of the lid domain were found to affect substrate specificity. The π-bond stacking between Tyr116 and Tyr149 played an important role in stabilizing the catalytic active center of LIP05. Tyr116 and Ile204 determined the substrate spectrum by composing the substrate-entrance channel. Residues Leu83, Ile204, Ile211 and Leu216 were involved in forming the hydrophobic substrate-binding pocket through steric hindrance and hydrophobic interaction. The catalytic mechanism for esterification in aqueous phase of LIP05 was proposed and provided a reference for clarifying the synthesis of fatty acid ethyl esters during the fermentation process of strong-flavor Baijiu.

18.
Front Microbiol ; 13: 891387, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35586860

RESUMO

Luzhou-flavoured liquor is one of Chinese most popular distilled liquors. Hundreds of flavoured components have been detected from this liquor, with esters as its primary flavouring substance. Among these esters, ethyl hexanoate was the main component. As an essential functional microbe that produces ethyl hexanoate, yeast is an important functional microorganism that produces ethyl hexanoate. The synthesis of ethyl hexanoate in yeast mainly involves the lipase/esterase synthesis pathway, alcohol transferase pathway and alcohol dehydrogenase pathway. In this study, whole-genome sequencing of W. anomalus Y-1 isolated from a Chinese liquor fermentation starter, a fermented wheat starter containing brewing microorganisms, was carried out using the Illumina HiSeq X Ten platform. The sequence had a length of 15,127,803 bp with 34.56% GC content, encoding 7,024 CDS sequences, 69 tRNAs and 1 rRNA. Then, genome annotation was performed using three high-quality databases, namely, COG, KEGG and GO databases. The annotation results showed that the ko7019 pathway of gene 6,340 contained the Eht1p enzyme, which was considered a putative acyltransferase similar to Eeb1p and had 51.57% homology with two known medium-chain fatty acid ethyl ester synthases, namely, Eht1 and Eeb1. Ethyl hexanoate in W. anomalus was found to be synthesised through the alcohol acyltransferase pathway, while acyl-coenzyme A and alcohol were synthesised under the catalytic action of Eht1p. The results of this study are beneficial to the exploration of key genes of ester synthesis and provide reference for the improvement of liquor flavoured.

19.
Food Res Int ; 157: 111369, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35761634

RESUMO

The medium-chain fatty acid ethyl esters (MCFAEEs) are a group of important aroma compounds generated during wine production. Wine alcohol fermentation involves several redox processes, which are affected by the oxidation-reduction potential (ORP). However, the mechanism via which ORP regulates MCFAEE production remains unclear. To investigate the effect of ORP on MCFAEE production, wine alcohol fermentation was performed using Saccharomyces cerevisiae under different ORPs. The results demonstrated that the ORPs studied (except for 90 mV) did not significantly affect cell growth, sugar consumption, and ethanol production, while the MCFAEE concentration in the simulated wines can be manipulated by ORP operation. MCFAEE levels increased till 96 h, and then decreased. The maximum MCFAEE level of 1222.97 µg/L was obtained after 96 h at 0 mV, which was 45.32% higher than that of the control. During the increase, higher relative expression of ACC1, FAS1, FAA2 and EEB1, elevated external citric acid flux, and moderate intracellular NADP+/NADPH ratio were observed at 0 mV compared to that at other ORPs. During the decrease, lowest relative expression of POX1 was detected at 0 mV. We showed for the first time the relationship between ORP operation and MCFAEE production in winemaking, which will improve the aroma quality of wine.


Assuntos
Vinho , Ésteres/análise , Ácidos Graxos/metabolismo , Fermentação , Oxirredução , Saccharomyces cerevisiae/metabolismo , Vinho/análise
20.
J Clin Exp Hepatol ; 12(6): 1514-1526, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36340303

RESUMO

Alcohol use disorder (AUD) is a common condition that develops on the background of heavy alcohol use and is characterised by the loss of control over alcohol use and a compulsion to use alcohol, often despite negative consequences. AUD is a leading cause for the resumption of alcohol use in patients with alcoholic liver disease (ALD) after treatment. Hence it is essential to screen all patients with ALD for the presence of AUD. Screening tools such as alcohol use disorders identification test (AUDIT) and AUDIT-C are used, following which the diagnosis and severity of AUD are determined using DSM-5 criteria. The management of AUD in patients with ALD is best carried out using an integrated approach involving psychiatrists and gastroenterologists/hepatologists. The treatment most often involves a combination of pharmacotherapy and psychosocial interventions which try to achieve and maintain abstinence. Although, there is limited evidence, Baclofen is the first line pharmacological agent for long-term management of AUD in patients with ALD. Intensive psychological interventions such as motivation enhancement therapy and cognitive behavioural therapy are also seen to be beneficial. Treatment retention and follow-up are vital and can positively influence outcomes.

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