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1.
Children (Basel) ; 10(12)2023 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-38136033

RESUMO

The municipality of Salvador, situated in Brazil, distinguished itself as the epicenter of the emergence of microcephaly related to congenital manifestations of Zika syndrome. Despite the anticipated significant developmental setbacks in these children, research has indicated a varied range of outcomes, with certain instances even reflecting minimal developmental delay. Our objective was to pinpoint determinants that could forecast developmental anomalies in children diagnosed with microcephaly associated with congenital Zika syndrome (CZS). METHODOLOGY: A forward-looking clinical and neurodevelopmental examination was conducted focusing on neonates diagnosed with microcephaly with CZS, birthed between September 2015 and April 2016 at the Hospital Geral Roberto Santos, in Salvador city. That infants were monitored up to their third year by a multiprofessional team. Child development was assessed using the composite Bayley III score. Undertaken by two blinded experts, cranial CT scan analysis was performed during the neonate period for the detection of brain abnormalities and to quantify ventricle enlargement, measured by Evans' index (EI). RESULTS: Fifty newborns were evaluated with a median head circumference of 28 cm (interquartile range 27-31 cm). EI was associated with neurodevelopmental delay at three years and remained significant after adjustment for head circumference. A 0.1-point increase in EI was associated with a delay of 3.2 months in the receptive language (p = 0.016), 3.4 months in the expressive language (p = 0.016), 3.4 months in the cognitive (p = 0.016), 2.37 months in the gross motor (p = 0.026), and 3.1 months in the fine motor (p = 0.021) domains. CONCLUSIONS: EI predicted neurodevelopmental delay in all Bayley domains in children with microcephaly associated with CZS.

2.
Stud Health Technol Inform ; 302: 1071-1072, 2023 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-37203584

RESUMO

Genomics has significantly impacted the field of medicine, with advances in DNA sequencing leading to personalized medicine and a deeper understanding of the genomic basis of various diseases. The ability to share genomic data is crucial for advancing this field and developing new approaches to understanding the genome. However, the sensitive nature of this data requires secure methods for protecting it during storage and transfer. In this paper, we present a new tool for the secure encryption and decryption of FASTA files without sharing a common secret and with a reduced number of shared keys between the pairs. Our proposal combines symmetric and asymmetric encryption techniques, including the AES (Advanced Encryption Standard) cypher and RSA (Rivest-Shamir-Adleman). The tool is fast, reliable, and secure, outperforming existing tools in terms of security and ease of use. This makes it a valuable solution for the secure sharing and use of sensitive genomic data, representing a significant advancement in the field of genomics.


Assuntos
Segurança Computacional , Genômica
3.
Database (Oxford) ; 20222022 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-35776534

RESUMO

The identification of chemicals in articles has attracted a large interest in the biomedical scientific community, given its importance in drug development research. Most of previous research have focused on PubMed abstracts, and further investigation using full-text documents is required because these contain additional valuable information that must be explored. The manual expert task of indexing Medical Subject Headings (MeSH) terms to these articles later helps researchers find the most relevant publications for their ongoing work. The BioCreative VII NLM-Chem track fostered the development of systems for chemical identification and indexing in PubMed full-text articles. Chemical identification consisted in identifying the chemical mentions and linking these to unique MeSH identifiers. This manuscript describes our participation system and the post-challenge improvements we made. We propose a three-stage pipeline that individually performs chemical mention detection, entity normalization and indexing. Regarding chemical identification, we adopted a deep-learning solution that utilizes the PubMedBERT contextualized embeddings followed by a multilayer perceptron and a conditional random field tagging layer. For the normalization approach, we use a sieve-based dictionary filtering followed by a deep-learning similarity search strategy. Finally, for the indexing we developed rules for identifying the more relevant MeSH codes for each article. During the challenge, our system obtained the best official results in the normalization and indexing tasks despite the lower performance in the chemical mention recognition task. In a post-contest phase we boosted our results by improving our named entity recognition model with additional techniques. The final system achieved 0.8731, 0.8275 and 0.4849 in the chemical identification, normalization and indexing tasks, respectively. The code to reproduce our experiments and run the pipeline is publicly available. Database URL https://github.com/bioinformatics-ua/biocreativeVII_track2.


Assuntos
Aprendizado Profundo , Heurística , Bases de Dados Factuais , Redes Neurais de Computação , PubMed
4.
Appl Biochem Biotechnol ; 193(7): 2182-2197, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33682050

RESUMO

During the pretreatment and hydrolysis of lignocellulosic biomass to obtain a hydrolysate rich in fermentable sugars, furaldehydes (furfural and hydroxymethylfurfural), phenolic compounds, and organic acids are formed and released. These compounds inhibit yeast metabolism, reducing fermentation yields and productivity. This study initially confirmed the ability of Spathaspora passalidarum to ferment xylose and demonstrated its sensibility to the inhibitors present in the hemicellulosic sugarcane bagasse hydrolysate. Then, an adaptive laboratory evolution, with progressive increments of hydrolysate concentration, was employed to select a strain more resistant to hydrolysate inhibitors. Afterward, a central composite design was performed to maximize ethanol production using hydrolysate as substrate. At optimized conditions (initial cell concentration of 30 g/L), S. passalidarum was able to produce 19.4 g/L of ethanol with productivity, yield, and xylose consumption rate of 0.8 g/L.h and 0.4 g/g, respectively, in a sugarcane bagasse hemicellulosic hydrolysate. A kinetic model was developed to describe the inhibition of fermentation by substrate and product. The values obtained for substrate saturation and inhibition constant were Ks = 120.4 g/L and Ki = 1293.4 g/L. Ethanol concentration that stops cell growth was 30.1 g/L. There was an agreement between simulated and experimental results, with a residual standard deviation lower than 6%.


Assuntos
Celulose/química , Etanol/metabolismo , Saccharomycetales/crescimento & desenvolvimento , Saccharum/química , Xilose , Xilose/química , Xilose/metabolismo
5.
Microorganisms ; 7(11)2019 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-31652879

RESUMO

Xylitol is a sugar alcohol with five carbons that can be used in the pharmaceutical and food industries. It is industrially produced by chemical route; however, a more economical and environmentally friendly production process is of interest. In this context, this study aimed to select wild yeasts able to produce xylitol and compare their performance in sugarcane bagasse hydrolysate. For this, 960 yeast strains, isolated from soil, wood, and insects have been prospected and selected for the ability to grow on defined medium containing xylose as the sole carbon source. A total of 42 yeasts was selected and their profile of sugar consumption and metabolite production were analyzed in microscale fermentation. The six best xylose-consuming strains were molecularly identified as Meyerozyma spp. The fermentative kinetics comparisons on defined medium and on sugarcane bagasse hydrolysate showed physiological differences among these strains. Production yields vary from YP/S = 0.25 g/g to YP/S = 0.34 g/g in defined medium and from YP/S = 0.41 g/g to YP/S = 0.60 g/g in the hydrolysate. Then, the xylitol production performance of the best xylose-consuming strain obtained in the screening, which was named M. guilliermondii B12, was compared with the previously reported xylitol producing yeasts M. guilliermondii A3, Spathaspora sp. JA1, and Wickerhamomyces anomalus 740 in sugarcane bagasse hydrolysate under oxygen-limited conditions. All the yeasts were able to metabolize xylose, but W. anomalus 740 showed the highest xylitol production yield, reaching a maximum of 0.83 g xylitol/g of xylose in hydrolysate. The screening strategy allowed identification of a new M. guilliermondii strain that efficiently grows in xylose even in hydrolysate with a high content of acetic acid (~6 g/L). In addition, this study reports, for the first time, a high-efficient xylitol producing strain of W. anomalus, which achieved, to the best of our knowledge, one of the highest xylitol production yields in hydrolysate reported in the literature.

6.
J Exp Med ; 216(10): 2302-2315, 2019 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-31413072

RESUMO

Zika virus (ZIKV) infection during pregnancy causes congenital abnormalities, including microcephaly. However, rates vary widely, and the contributing risk factors remain unclear. We examined the serum antibody response to ZIKV and other flaviviruses in Brazilian women giving birth during the 2015-2016 outbreak. Infected pregnancies with intermediate or higher ZIKV antibody enhancement titers were at increased risk to give birth to microcephalic infants compared with those with lower titers (P < 0.0001). Similarly, analysis of ZIKV-infected pregnant macaques revealed that fetal brain damage was more frequent in mothers with higher enhancement titers. Thus, features of the maternal antibodies are associated with and may contribute to the genesis of ZIKV-associated microcephaly.


Assuntos
Anticorpos Antivirais/imunologia , Troca Materno-Fetal/imunologia , Microcefalia/imunologia , Complicações Infecciosas na Gravidez/imunologia , Infecção por Zika virus/imunologia , Zika virus/imunologia , Animais , Encéfalo/embriologia , Encéfalo/imunologia , Encéfalo/patologia , Feminino , Feto/embriologia , Feto/imunologia , Feto/patologia , Humanos , Células K562 , Macaca mulatta , Macaca nemestrina , Microcefalia/patologia , Gravidez , Complicações Infecciosas na Gravidez/patologia , Infecção por Zika virus/patologia
7.
BMC Biotechnol ; 19(1): 58, 2019 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-31382948

RESUMO

BACKGROUND: Efficient xylose fermentation still demands knowledge regarding xylose catabolism. In this study, metabolic flux analysis (MFA) and metabolomics were used to improve our understanding of xylose metabolism. Thus, a stoichiometric model was constructed to simulate the intracellular carbon flux and used to validate the metabolome data collected within xylose catabolic pathways of non-Saccharomyces xylose utilizing yeasts. RESULTS: A metabolic flux model was constructed using xylose fermentation data from yeasts Scheffersomyces stipitis, Spathaspora arborariae, and Spathaspora passalidarum. In total, 39 intracellular metabolic reactions rates were utilized validating the measurements of 11 intracellular metabolites, acquired by mass spectrometry. Among them, 80% of total metabolites were confirmed with a correlation above 90% when compared to the stoichiometric model. Among the intracellular metabolites, fructose-6-phosphate, glucose-6-phosphate, ribulose-5-phosphate, and malate are validated in the three studied yeasts. However, the metabolites phosphoenolpyruvate and pyruvate could not be confirmed in any yeast. Finally, the three yeasts had the metabolic fluxes from xylose to ethanol compared. Xylose catabolism occurs at twice-higher flux rates in S. stipitis than S. passalidarum and S. arborariae. Besides, S. passalidarum present 1.5 times high flux rate in the xylose reductase reaction NADH-dependent than other two yeasts. CONCLUSIONS: This study demonstrated a novel strategy for metabolome data validation and brought insights about naturally xylose-fermenting yeasts. S. stipitis and S. passalidarum showed respectively three and twice higher flux rates of XR with NADH cofactor, reducing the xylitol production when compared to S. arborariae. Besides then, the higher flux rates directed to pentose phosphate pathway (PPP) and glycolysis pathways resulted in better ethanol production in S. stipitis and S. passalidarum when compared to S. arborariae.


Assuntos
Fermentação , Análise do Fluxo Metabólico/métodos , Metaboloma , Metabolômica/métodos , Saccharomycetales/metabolismo , Frutosefosfatos/metabolismo , Glucose-6-Fosfato/metabolismo , Glicólise , Malatos/metabolismo , Espectrometria de Massas/métodos , Modelos Biológicos , Via de Pentose Fosfato , Ribulosefosfatos/metabolismo , Saccharomycetales/classificação , Leveduras/classificação , Leveduras/metabolismo
8.
FEMS Yeast Res ; 19(4)2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-31073598

RESUMO

Xylitol is a five-carbon polyol of economic interest that can be produced by microbial xylose reduction from renewable resources. The current study sought to investigate the potential of two yeast strains, isolated from Brazilian Cerrado biome, in the production of xylitol as well as the genomic characteristics that may impact this process. Xylose conversion capacity by the new isolates Spathaspora sp. JA1 and Meyerozyma caribbica JA9 was evaluated and compared with control strains on xylose and sugarcane biomass hydrolysate. Among the evaluated strains, Spathaspora sp. JA1 was the strongest xylitol producer, reaching product yield and productivity as high as 0.74 g/g and 0.20 g/(L.h) on xylose, and 0.58 g/g and 0.44 g/(L.h) on non-detoxified hydrolysate. Genome sequences of Spathaspora sp. JA1 and M. caribbica JA9 were obtained and annotated. Comparative genomic analysis revealed that the predicted xylose metabolic pathway is conserved among the xylitol-producing yeasts Spathaspora sp. JA1, M. caribbica JA9 and Meyerozyma guilliermondii, but not in Spathaspora passalidarum, an efficient ethanol-producing yeast. Xylitol-producing yeasts showed strictly NADPH-dependent xylose reductase and NAD+-dependent xylitol-dehydrogenase activities. This imbalance of cofactors favors the high xylitol yield shown by Spathaspora sp. JA1, which is similar to the most efficient xylitol producers described so far.


Assuntos
Microbiologia Industrial , Saccharomycetales/genética , Saccharomycetales/fisiologia , Xilitol/biossíntese , Biomassa , Brasil , Fermentação , Genoma Fúngico , Genômica , Redes e Vias Metabólicas , Saccharomycetales/isolamento & purificação , Xilose/metabolismo
9.
Yeast ; 36(5): 349-361, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30997699

RESUMO

Xylitol is a building block for a variety of chemical commodities, besides being widely used as a sugar substitute in the food and pharmaceutical industries. The aim of this work was to develop a microbial process for xylitol production using sugarcane bagasse hydrolysate as substrate. In this context, 218 non-Saccharomyces yeast strains were screened by growth on steam-exploded sugarcane bagasse hydrolysate containing a high concentration of acetic acid (8.0 g/L). Seven new Candida tropicalis strains were selected and identified, and their ability to produce xylitol on hydrolysate at low pH (4.6) under aerobic conditions was evaluated. The most efficient strain, designated C. tropicalis JA2, was capable of producing xylitol with a yield of 0.47 g/g of consumed xylose. To improve xylitol production by C. tropicalis JA2, a series of experimental procedures were employed to optimize pH and temperature conditions, as well as nutrient source, and initial xylose and inoculum concentrations. C. tropicalis JA2 was able to produce 109.5 g/L of xylitol with a yield of 0.86 g/g of consumed xylose, and with a productivity of 2.81 g·L·h, on sugarcane bagasse hydrolysate containing 8.0 g/L acetic acid and177 g/L xylose, supplemented with 2.0 g/L yeast nitrogen base and 4.0 g/L urea. Thus, it was possible to identify a new C. tropicalis strain and to optimize the xylitol production process using sugarcane bagasse hydrolysate as a substrate. The xylitol yield on biomass hydrolysate containing a high concentration of acetic acidobtained in here is among the best reported in the literature.


Assuntos
Ácido Acético/metabolismo , Biomassa , Candida tropicalis/metabolismo , Saccharum/metabolismo , Xilitol/biossíntese , Aerobiose , Celulose/metabolismo , Fermentação , Concentração de Íons de Hidrogênio , Hidrólise , Xilose/metabolismo
10.
J Surg Case Rep ; 2018(8): rjy227, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30151116

RESUMO

Gastric volvulus is an uncommon cause of gastric obstruction. It can be classified as primary when no underlying condition is identified as the cause for the rotation. An acute presentation includes typical symptoms and is frequently detected by imaging studies. Chronic cases present with intermittent vague symptoms and imaging studies may be normal during the symptomatic interval. The lack of specific symptoms and signs delays the diagnosis of chronic volvulus. However, appropriate treatment demands prompt diagnosis. We report two cases of primary gastric volvulus, with chronic or subacute symptoms and normal imaging studies during the asymptomatic periods. Both were treated surgically and had an uneventful follow-up.

11.
Biotechnol Biofuels ; 5(1): 48, 2012 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-22809320

RESUMO

The considerable increase in biodiesel production worldwide in the last 5 years resulted in a stoichiometric increased coproduction of crude glycerol. As an excess of crude glycerol has been produced, its value on market was reduced and it is becoming a "waste-stream" instead of a valuable "coproduct". The development of biorefineries, i.e. production of chemicals and power integrated with conversion processes of biomass into biofuels, has been singled out as a way to achieve economically viable production chains, valorize residues and coproducts, and reduce industrial waste disposal. In this sense, several alternatives aimed at the use of crude glycerol to produce fuels and chemicals by microbial fermentation have been evaluated. This review summarizes different strategies employed to produce biofuels and chemicals (1,3-propanediol, 2,3-butanediol, ethanol, n-butanol, organic acids, polyols and others) by microbial fermentation of glycerol. Initially, the industrial use of each chemical is briefly presented; then we systematically summarize and discuss the different strategies to produce each chemical, including selection and genetic engineering of producers, and optimization of process conditions to improve yield and productivity. Finally, the impact of the developments obtained until now are placed in perspective and opportunities and challenges for using crude glycerol to the development of biodiesel-based biorefineries are considered. In conclusion, the microbial fermentation of glycerol represents a remarkable alternative to add value to the biodiesel production chain helping the development of biorefineries, which will allow this biofuel to be more competitive.

12.
Biotechnol J ; 6(3): 286-99, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21305697

RESUMO

Conversion of agricultural residues, energy crops and forest residues into bioethanol requires hydrolysis of the biomass and fermentation of the released sugars. During the hydrolysis of the hemicellulose fraction, substantial amounts of pentose sugars, in particular xylose, are released. Fermentation of these pentose sugars to ethanol by engineered Saccharomyces cerevisiae under industrial process conditions is the subject of this review. First, fermentation challenges originating from the main steps of ethanol production from lignocellulosic feedstocks are discussed, followed by genetic modifications that have been implemented in S. cerevisiae to obtain xylose and arabinose fermenting capacity per se. Finally, the fermentation of a real lignocellulosic medium is discussed in terms of inhibitory effects of furaldehydes, phenolics and weak acids and the presence of contaminating microbiota.


Assuntos
Etanol/metabolismo , Microbiologia Industrial , Pentoses/metabolismo , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/metabolismo , Estresse Fisiológico , Arabinose/metabolismo , Fermentação , Engenharia Genética , Hidrólise , Polissacarídeos/metabolismo , Saccharomyces cerevisiae/genética , Xilose/metabolismo
13.
Anal Chem ; 81(24): 9896-901, 2009 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-19925001

RESUMO

In this work, mediated amperometry was used to evaluate whether differences in intracellular nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) level could be observed between a genetically modified Saccharomyces cerevisiae strain, engineered for NADPH dependent 5-hydroxymethyl-2-furaldehyde (HMF) reduction, and its control strain. Cells overexpressing the alcohol dehydrogenase 6 gene (ADH6 strain) and cells carrying the corresponding control plasmid (control strain) were each immobilized on Au-microelectrodes. The real-time dynamics of NAD(P)H availability in the two strains, preincubated with HMF, was probed using the menadione-ferricyanide double mediator system. A lower intracellular NADPH level as the consequence of more effective HMF reduction was observed for the ADH6 strain both with and without added glucose, which increases the overall cellular NADPH level. The mediated amperometric signal during real-time monitoring of the concentration dependent HMF reduction in living cells could be translated into the cellular enzyme kinetic parameters: K(M,cell)(app), V(MAX), k(cat,cell), and k(cat,cell)/K)M,cell)(app). The results indicated that the overexpression of the ADH6 gene gave a 68% decrease in K(M,cell)(app) and 42% increase in V(MAX), resulting in a 4-fold increase in k(cat,cell)/K(M,cell)(app). These results demonstrate that the mediated amperometric method is useful for monitoring the short-term dynamics of NAD(P)H variations and determining cellular enzyme kinetic parameters in S. cerevisiae cells.


Assuntos
Furaldeído/análogos & derivados , Ouro/química , Saccharomyces cerevisiae/metabolismo , Eletroquímica , Furaldeído/química , Furaldeído/metabolismo , Microeletrodos , NADP/metabolismo , Oxirredução , Saccharomyces cerevisiae/enzimologia , Propriedades de Superfície
14.
Appl Microbiol Biotechnol ; 84(4): 751-61, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19506862

RESUMO

Industrial Saccharomyces cerevisiae strains able to utilize xylose have been constructed by overexpression of XYL1 and XYL2 genes encoding the NADPH-preferring xylose reductase (XR) and the NAD(+)-dependent xylitol dehydrogenase (XDH), respectively, from Pichia stipitis. However, the use of different co-factors by XR and XDH leads to NAD(+) deficiency followed by xylitol excretion and reduced product yield. The furaldehydes 5-hydroxymethyl-furfural (HMF) and furfural inhibit yeast metabolism, prolong the lag phase, and reduce the ethanol productivity. Recently, genes encoding furaldehyde reductases were identified and their overexpression was shown to improve S. cerevisiae growth and fermentation rate in HMF containing media and in lignocellulosic hydrolysate. In the current study, we constructed a xylose-consuming S. cerevisiae strain using the XR/XDH pathway from P. stipitis. Then, the genes encoding the NADH- and the NADPH-dependent HMF reductases, ADH1-S110P-Y295C and ADH6, respectively, were individually overexpressed in this background. The performance of these strains, which differed in their co-factor usage for HMF reduction, was evaluated under anaerobic conditions in batch fermentation in absence or in presence of HMF. In anaerobic continuous culture, carbon fluxes were obtained for simultaneous xylose consumption and HMF reduction. Our results show that the co-factor used for HMF reduction primarily influenced formation of products other than ethanol, and that NADH-dependent HMF reduction influenced product formation more than NADPH-dependent HMF reduction. In particular, NADH-dependent HMF reduction contributed to carbon conservation so that biomass was produced at the expense of xylitol and glycerol formation.


Assuntos
Antifúngicos/metabolismo , Carbono/metabolismo , Furaldeído/análogos & derivados , NADP/metabolismo , NAD/metabolismo , Saccharomyces cerevisiae/metabolismo , Xilose/metabolismo , Aldeído Redutase/genética , Aldeído Redutase/metabolismo , Anaerobiose , Antifúngicos/farmacologia , Clonagem Molecular , D-Xilulose Redutase/genética , D-Xilulose Redutase/metabolismo , Etanol/metabolismo , Furaldeído/metabolismo , Furaldeído/farmacologia , Expressão Gênica , Glicerol/metabolismo , Oxirredução , Pichia/enzimologia , Pichia/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/genética , Xilitol/metabolismo
15.
Bioresour Technol ; 100(14): 3674-7, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19329297

RESUMO

A microplate screening method was used to assess anaerobic growth of 12 Saccharomyces cerevisiae strains in barley straw, spruce and wheat straw hydrolysate. The assay demonstrated significant differences in inhibitor tolerance among the strains. In addition, growth inhibition by the three hydrolysates differed so that wheat hydrolysate supported growth up to 70%, while barley hydrolysate only supported growth up to 50%, with dilute-acid spruce hydrolysate taking an intermediate position.


Assuntos
Biotecnologia/métodos , Etanol/química , Hordeum/metabolismo , Microbiologia Industrial/métodos , Lignina/química , Saccharomyces cerevisiae/metabolismo , Biomassa , Reatores Biológicos , Fermentação , Hidrólise , Especificidade da Espécie
16.
Appl Microbiol Biotechnol ; 82(4): 625-38, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19184597

RESUMO

There is a growing awareness that lignocellulose will be a major raw material for production of both fuel and chemicals in the coming decades--most likely through various fermentation routes. Considerable attention has been given to the problem of finding efficient means of separating the major constituents in lignocellulose (i.e., lignin, hemicellulose, and cellulose) and to efficiently hydrolyze the carbohydrate parts into sugars. In these processes, by-products will inevitably form to some extent, and these will have to be dealt with in the ensuing microbial processes. One group of compounds in this category is the furaldehydes. 2-Furaldehyde (furfural) and substituted 2-furaldehydes--most importantly 5-hydroxymethyl-2-furaldehyde--are the dominant inhibitory compounds found in lignocellulosic hydrolyzates. The furaldehydes are known to have biological effects and act as inhibitors in fermentation processes. The effects of these compounds will therefore have to be considered in the design of biotechnological processes using lignocellulose. In this short review, we take a look at known metabolic effects, as well as strategies to overcome problems in biotechnological applications caused by furaldehydes.


Assuntos
Bactérias/metabolismo , Biotecnologia , Fungos/metabolismo , Furaldeído/metabolismo , Bactérias/genética , Fermentação , Fungos/genética , Engenharia Genética , Lignina/química , Lignina/metabolismo
17.
Biotechnol Bioeng ; 100(3): 423-9, 2008 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-18438882

RESUMO

The development of tolerant microorganisms is needed for the efficient fermentation of inhibitory lignocellulose hydrolysates. In the current work, the fermentation performance of six selected strains of Saccharomyces cerevisiae in dilute-acid spruce hydrolysate was compared using two different modes of fermentation; either single pulse addition of hydrolysate to exponentially growing cells or continuous feeding of the same amount of hydrolysate in a controlled fed-batch fermentation was made. All strains performed better in fed-batch mode than when all hydrolysate was added at once. However, the difference between strain performances varied significantly in the two fermentation modes. Large differences were observed between strains during the fed-batch experiments in the in vitro ability to reduce the furan compounds furfural and 5-hydroxymethyl furfural (HMF). A common feature among the strains was the induction of NADPH-coupled reduction of furfural and HMF, with the exception of strain CBS 8066. This strain also performed relatively poorly in both batch and fed-batch fermentations. Strain TMB3000--previously isolated from spent sulphite liquor fermentation--was by far the most efficient strain with respect to specific fermentation rate in both pulse addition and fed-batch mode. This strain was the only strain showing a significant constitutive NADH-coupled in vitro reduction of HMF. The ability to induce NADPH-coupled reduction together with the level of the apparently constitutive NADH-coupled reduction appeared to be key factors for selecting a suitable strain for fed-batch conversion of lignocellulose hydrolysate.


Assuntos
Celulose/metabolismo , Fermentação , Microbiologia Industrial , Lignina/metabolismo , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/metabolismo , Etanol/metabolismo , Furaldeído/análogos & derivados , Furaldeído/metabolismo , Hidrólise , NADP/metabolismo , Oxirredução
18.
Appl Microbiol Biotechnol ; 78(6): 939-45, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18330568

RESUMO

Saccharomyces cerevisiae alcohol dehydrogenases responsible for NADH-, and NADPH-specific reduction of the furaldehydes 5-hydroxymethyl-furfural (HMF) and furfural have previously been identified. In the present study, strains overexpressing the corresponding genes (mut-ADH1 and ADH6), together with a control strain, were compared in defined medium for anaerobic fermentation of glucose in the presence and absence of HMF. All strains showed a similar fermentation pattern in the absence of HMF. In the presence of HMF, the strain overexpressing ADH6 showed the highest HMF reduction rate and the highest specific ethanol productivity, followed by the strain overexpressing mut-ADH1. This correlated with in vitro HMF reduction capacity observed in the ADH6 overexpressing strain. Acetate and glycerol yields per biomass increased considerably in the ADH6 strain. In the other two strains, only the overall acetate yield per biomass was affected. When compared in batch fermentation of spruce hydrolysate, strains overexpressing ADH6 and mut-ADH1 had five times higher HMF uptake rate than the control strain and improved specific ethanol productivity. Overall, our results demonstrate that (1) the cofactor usage in the HMF reduction affects the product distribution, and (2) increased HMF reduction activity results in increased specific ethanol productivity in defined mineral medium and in spruce hydrolysate.


Assuntos
Furaldeído/análogos & derivados , Microbiologia Industrial , NADP/metabolismo , NAD/metabolismo , Saccharomyces cerevisiae/metabolismo , Álcool Desidrogenase/genética , Álcool Desidrogenase/metabolismo , Anaerobiose , Biomassa , Meios de Cultura/química , Fermentação , Furaldeído/metabolismo , Oxirredução , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Especificidade da Espécie
19.
Yeast ; 25(3): 191-8, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18302314

RESUMO

We report on the identification and characterization of a mutated alcohol dehydrogenase 1 from the industrial Saccharomyces cerevisiae strain TMB3000 that mediates the NADH-dependent reduction of 5-hydroxymethylfurfural (HMF) to 2,5-bis-hydroxymethylfuran. The co-factor preference distinguished this alcohol dehydrogenase from the previously reported NADPH-dependent S. cerevisiae HMF alcohol dehydrogenase Adh6. The amino acid sequence revealed three novel mutations (S109P, L116S and Y294C) that were all predicted at the vicinity of the substrate binding site, which could explain the unusual substrate specificity. Increased biomass production and HMF conversion rate were achieved in a CEN.PK S. cerevisiae strain overexpressing the mutated ADH1 gene.


Assuntos
Álcool Desidrogenase/isolamento & purificação , Furaldeído/análogos & derivados , NAD/metabolismo , Proteínas de Saccharomyces cerevisiae/isolamento & purificação , Saccharomyces cerevisiae/metabolismo , Álcool Desidrogenase/genética , Álcool Desidrogenase/metabolismo , Sequência de Aminoácidos , Clonagem Molecular , Coenzimas/metabolismo , Furaldeído/metabolismo , Espectrometria de Massas , Oxirredução , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crescimento & desenvolvimento , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Especificidade por Substrato
20.
Arch Biochem Biophys ; 465(1): 61-71, 2007 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-17573033

RESUMO

The biosynthesis of flavonoids and proanthocyanidins was studied in cultivated strawberry (Fragaria xananassa) by combining biochemical and molecular approaches. Chemical analyses showed that ripe strawberries accumulate high amounts of pelargonidin-derived anthocyanins, and a larger pool of 3',4'-hydroxylated proanthocyanidins. Activities and properties of major recombinant enzymes were demonstrated by means of in vitro assays, with special emphasis on specificity for the biologically relevant 4'- and 3',4'-hydroxylated compounds. Only leucoanthocyanidin reductase showed a strict specificity for the 3',4'-hydroxylated leucocyanidin, while other enzymes accepted either hydroxylated substrate with different relative activity rates. The structure of late flavonoid pathway genes, leading to the synthesis of major compounds in ripe fruits, was elucidated. Complex developmental and spatial expression patterns were shown for phenylpropanoid and flavonoid genes in fruits throughout ripening as well as in leaves, petals and roots. Presented results elucidate key steps in the biosynthesis of strawberry flavonoid end products.


Assuntos
Enzimas/metabolismo , Flavonoides/metabolismo , Fragaria/fisiologia , Frutas/fisiologia , Proteínas de Plantas/metabolismo , Proantocianidinas/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Regulação Enzimológica da Expressão Gênica/fisiologia , Transdução de Sinais/fisiologia
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