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1.
Int J Food Microbiol ; 333: 108796, 2020 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-32771820

RESUMO

The objective of this study was to investigate the role of yeasts in the wet fermentation of coffee beans and their contribution to coffee quality using a novel approach. Natamycin (300 ppm) was added to the fermentation mass to suppress yeast growth and their metabolic activities, and the resultant microbial ecology, bean chemistry and sensory quality were analyzed and compared to non-treated spontaneous fermentation we reported previously. The yeast community was dominated by Hanseniaspora uvarum and Pichia kudriavzevii and grew to a maximum population of about 5.5 log CFU/g in the absence of Natamycin, while when Natamycin was added yeasts were suppressed. The major bacterial species in both the spontaneous and yeast-suppressed fermentations included the lactic acid bacteria Leuconostoc mesenteroides and Lactococcus lactis, the acetic acid bacteria Gluconobacter cerinus and Acetobacter persici and the Enterobacteriaceae Enterobacter, Citrobacter and Erwinia. For both fermentations, the mucilage layers were completely degraded by the end of the process and the absence of yeast activities had no significant impact on mucilage degradation. During fermentation, reducing sugars were consumed while lactic acid was accumulated inside the beans, and its concentration was significantly higher in the spontaneous fermentation (3 times) than that where yeasts were suppressed by Natamycin. Glycerol was detected with a concentration of 0.08% in the absence of Natamycin and was not identified when Natamycin was added. Green beans fermented with yeast growth contained a higher amount of isoamyl alcohol (21 times), ethanol (3.7 times), acetaldehyde (8 times), and ethyl acetate (25 times) compared to beans fermented in the absence of yeast activities, which remained higher in the former after roasting. Beans fermented without yeast activities had a mild fruity aroma, and lower sensory scores of fragrances (7.0), flavor (6.5), acidity (6.3), body (7.0) and overall score (6.5) compared to the former. These findings demonstrated the crucial roles of yeasts in wet fermentation of coffee beans and for producing high quality coffee.


Assuntos
Bactérias/metabolismo , Café/metabolismo , Fermentação/fisiologia , Hanseniaspora/metabolismo , Pichia/metabolismo , Leveduras/metabolismo , Acetaldeído/metabolismo , Acetatos/metabolismo , Ácido Acético/metabolismo , Anti-Infecciosos/farmacologia , Bactérias/classificação , Reatores Biológicos/microbiologia , Café/microbiologia , Etanol/metabolismo , Ácido Láctico/metabolismo , Natamicina/farmacologia , Odorantes/análise , Pentanóis/metabolismo , Paladar
2.
Chemosphere ; 258: 127320, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32554008

RESUMO

Microorganisms play important roles in the degradation of volatile organic compounds. Aeromonas salmonicida strain (AEP-3) generated from biomass in the citric acid fermentation industry was screened and subjected to denaturing gradient gel electrophoresis (DGGE) fingerprinting and 16S rDNA gene sequencing. The growth conditions of AEP-3 in Luria-Bertani broth were optimized at 25 °C and approximately pH 7. AEP-3 was used to degrade ethyl formate, propionic aldehyde, or acetone alone and their mixture. The concentrations of ethyl formate, propionic aldehyde, and acetone were below 7500, 600, and 800 mg L-1, respectively, and their maximum degradation efficiencies were 100%, 92.41%, and 34.75%. AEP-3 first degraded acetone and propionic aldehyde in the mixture, followed by ethyl formate. The degradation pathways of these organic compounds in the mixture and their substrate interactions during degradation were explored. Propionic aldehyde was first converted into propionic acid in the metabolic process and was involved in the subsequent carboxylic acid cycle. By contrast, ethyl formate was first hydrolyzed into formic acid and ethanol. Then, formic acid participated in the cyclic metabolism of carboxylic acid, whereas, ethanol was hydrolyzed into acetaldehyde and acetic acid through alcohol and aldehyde dehydrogenase. Additionally, acetone directly interacted with nitrate in the medium under the action of hydrogen ions and produced carbon dioxide, water, and nitrogen. Overall, this study provides a new degrading bacterium biodegradability toward the exhaust gas of citric acid fermentation.


Assuntos
Acetona/metabolismo , Aeromonas salmonicida/metabolismo , Ésteres do Ácido Fórmico/metabolismo , Acetaldeído , Ácido Acético/metabolismo , Biodegradação Ambiental , Biomassa , Ácido Cítrico/metabolismo , Etanol/metabolismo , Fermentação , Formiatos , Propionatos/metabolismo
3.
Int J Food Microbiol ; 329: 108651, 2020 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-32512285

RESUMO

In Latin, 'pulcherrima' is a superlative form of an adjective that translates as beautiful. Apart from being 'the most beautiful' yeast, Metschnikowia pulcherrima has a remarkable potential in production of wines with lower ethanol content. The oenological performance of six M. pulcherrima strains was hereby tested in sequential cultures with Saccharomyces cerevisiae. The best-performing strain MP2 was further characterised in fermentations with different S. cerevisiae inoculation delays in both white grape juice and Chemically Defined Grape Juice Medium (CDGJM). The analysis of main metabolites, undertaken prior to sequential inoculations and upon fermentation completion, highlighted metabolic interactions and carbon sinks other than ethanol in MP2 treatments. Depending on the inoculation delay, MP2 white wines contained between 0.6% and 1.2% (v/v) less ethanol than the S. cerevisiae monoculture, with even larger decreases detected in the CDGJM. The MP2 treatments also contained higher concentrations of TCA cycle by-products (i.e. fumarate and succinate) and glycerol, and lower concentrations of acetic acid. The analysis of volatile compounds showed increased production of acetate esters and higher alcohols in all MP2 wines, alongside other compositional alterations arising from the S. cerevisiae inoculation delay.


Assuntos
Fermentação , Microbiologia de Alimentos/métodos , Metschnikowia/metabolismo , Saccharomyces cerevisiae/metabolismo , Vinho/microbiologia , Ácido Acético/metabolismo , Etanol/metabolismo , Glicerol/metabolismo , Fatores de Tempo , Vitis/metabolismo , Vitis/microbiologia , Vinho/análise
4.
Int J Food Microbiol ; 324: 108615, 2020 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-32371236

RESUMO

In recent years, CRISPR/Cas9-based genetic editing has become a mainstay in many laboratories including manipulations done with yeast. We utilized this technique to generate a self-cloned wine yeast strain that overexpresses two genes of oenological relevance i.e. the glycerol-3-phosphate dehydrogenase 1 (GPD1) and the alcohol acetyltransferase 1 (ATF1) directly implicated in glycerol and acetate ester production respectively. Riesling wine made from the resulting strain showed increased glycerol and acetate ester levels compared to the parental strain. In addition, significantly less acetic acid levels were measured in wine made with yeast containing both genetic alterations compared to wine made with the strain that only overexpresses GPD1. Thus, this strain provides an alternative strategy for alleviating the accumulation of acetic acid once glycerol production is favoured during alcoholic fermentation with the addition of dramatically increasing acetate esters production.


Assuntos
Sistemas CRISPR-Cas , Saccharomyces cerevisiae/genética , Vinho/microbiologia , Ácido Acético/análise , Ácido Acético/metabolismo , Fermentação , Edição de Genes , Glicerol/análise , Glicerol/metabolismo , Glicerol-3-Fosfato Desidrogenase (NAD+)/genética , Glicerol-3-Fosfato Desidrogenase (NAD+)/metabolismo , Fenótipo , Proteínas/genética , Proteínas/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Vinho/análise
5.
PLoS One ; 15(5): e0227591, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32433654

RESUMO

Plants emit high rates of methanol (meOH), generally assumed to derive from pectin demethylation, and this increases during abiotic stress. In contrast, less is known about the emission and source of acetic acid (AA). In this study, Populus trichocarpa (California poplar) leaves in different developmental stages were desiccated and quantified for total meOH and AA emissions together with bulk cell wall acetylation and methylation content. While young leaves showed high emissions of meOH (140 µmol m-2) and AA (42 µmol m-2), emissions were reduced in mature (meOH: 69%, AA: 60%) and old (meOH: 83%, AA: 76%) leaves. In contrast, the ratio of AA/meOH emissions increased with leaf development (young: 35%, mature: 43%, old: 82%), mimicking the pattern of O-acetyl/methyl ester ratios of leaf bulk cell walls (young: 35%, mature: 38%, old: 51%), which is driven by an increase in O-acetyl and decrease in methyl ester content with age. The results are consistent with meOH and AA emission sources from cell wall de-esterification, with young expanding tissues producing highly methylated pectin that is progressively demethyl-esterified. We highlight the quantification of AA/meOH emission ratios as a potential tool for rapid phenotype screening of structural carbohydrate esterification patterns.


Assuntos
Ácido Acético/metabolismo , Parede Celular/metabolismo , Metanol/metabolismo , Folhas de Planta/metabolismo , Acetilação , Atmosfera , Hidrolases de Éster Carboxílico/metabolismo , Esterificação , Metilação , Pectinas/metabolismo , Folhas de Planta/crescimento & desenvolvimento , Proteínas de Plantas/genética , Populus/efeitos dos fármacos , Populus/crescimento & desenvolvimento , Populus/metabolismo , Estresse Fisiológico/genética
6.
Nat Commun ; 11(1): 1998, 2020 04 24.
Artigo em Inglês | MEDLINE | ID: mdl-32332730

RESUMO

Alcohol consumption is a consistent protective factor for the development of autoimmune diseases such as rheumatoid arthritis (RA). The underlying mechanism for this tolerance-inducing effect of alcohol, however, is unknown. Here we show that alcohol and its metabolite acetate alter the functional state of T follicular helper (TFH) cells in vitro and in vivo, thereby exerting immune regulatory and tolerance-inducing properties. Alcohol-exposed mice have reduced Bcl6 and PD-1 expression as well as IL-21 production by TFH cells, preventing proper spatial organization of TFH cells to form TFH:B cell conjugates in germinal centers. This effect is associated with impaired autoantibody formation, and mitigates experimental autoimmune arthritis. By contrast, T cell independent immune responses and passive models of arthritis are not affected by alcohol exposure. These data clarify the immune regulatory and tolerance-inducing effect of alcohol consumption.


Assuntos
Consumo de Bebidas Alcoólicas/imunologia , Artrite Experimental/imunologia , Artrite Reumatoide/imunologia , Etanol/farmacologia , Linfócitos T Auxiliares-Indutores/efeitos dos fármacos , Ácido Acético/metabolismo , Ácido Acético/farmacologia , Animais , Artrite Experimental/prevenção & controle , Artrite Reumatoide/prevenção & controle , Autoanticorpos/imunologia , Autoimunidade/efeitos dos fármacos , Linfócitos B/efeitos dos fármacos , Linfócitos B/imunologia , Colágeno/administração & dosagem , Colágeno/imunologia , Etanol/metabolismo , Feminino , Humanos , Camundongos , Fatores de Proteção , Tolerância a Antígenos Próprios/efeitos dos fármacos , Linfócitos T Auxiliares-Indutores/imunologia
7.
Pol J Microbiol ; 69(1): 109-120, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32189481

RESUMO

Hydrogen produced from lignocellulose biomass is deemed as a promising fuel of the future. However, direct cellulose utilization remains an issue due to the low hydrogen yields. In this study, the long-term effect of inoculum (anaerobic sludge) heat pretreatment on hydrogen production from untreated cellulose and starch was evaluated during repeated batch processes. The inoculum pretreatment at 90°C was not sufficient to suppress H2 consuming bacteria, both for starch and cellulose. Although hydrogen was produced, it was rapidly utilized with simultaneous accumulation of acetic and propionic acid. The pretreatment at 100°C (20 min) resulted in the successful enrichment of hydrogen producers on starch. High production of hydrogen (1.2 l H2/lmedium) and H2 yield (1.7 mol H2/molhexose) were maintained for 130 days, with butyric (1.5 g/l) and acetic acid (0.65 g/l) as main byproducts. On the other hand, the process with cellulose showed lower hydrogen production (0.3 l H2/lmedium) with simultaneous high acetic acid (1.4 g/l) and ethanol (1.2 g/l) concentration. Elimination of sulfates from the medium led to the efficient production of hydrogen in the initial cycles - 0.97 mol H2/molhexose (5.93 mmol H2/gcellulose). However, the effectiveness of pretreatment was only temporary for cellulose, because propionic acid accumulation (1.5 g/l) was observed after 25 days, which resulted in lower H2 production. The effective production of hydrogen from cellulose was also maintained for 40 days in a repeated fed-batch process (0.63 mol H2/molhexose).Hydrogen produced from lignocellulose biomass is deemed as a promising fuel of the future. However, direct cellulose utilization remains an issue due to the low hydrogen yields. In this study, the long-term effect of inoculum (anaerobic sludge) heat pretreatment on hydrogen production from untreated cellulose and starch was evaluated during repeated batch processes. The inoculum pretreatment at 90°C was not sufficient to suppress H2 consuming bacteria, both for starch and cellulose. Although hydrogen was produced, it was rapidly utilized with simultaneous accumulation of acetic and propionic acid. The pretreatment at 100°C (20 min) resulted in the successful enrichment of hydrogen producers on starch. High production of hydrogen (1.2 l H2/lmedium) and H2 yield (1.7 mol H2/molhexose) were maintained for 130 days, with butyric (1.5 g/l) and acetic acid (0.65 g/l) as main byproducts. On the other hand, the process with cellulose showed lower hydrogen production (0.3 l H2/lmedium) with simultaneous high acetic acid (1.4 g/l) and ethanol (1.2 g/l) concentration. Elimination of sulfates from the medium led to the efficient production of hydrogen in the initial cycles ­ 0.97 mol H2/molhexose (5.93 mmol H2/gcellulose). However, the effectiveness of pretreatment was only temporary for cellulose, because propionic acid accumulation (1.5 g/l) was observed after 25 days, which resulted in lower H2 production. The effective production of hydrogen from cellulose was also maintained for 40 days in a repeated fed-batch process (0.63 mol H2/molhexose).


Assuntos
Celulose/metabolismo , Fermentação , Hidrogênio/metabolismo , Consórcios Microbianos , Amido/metabolismo , Ácido Acético/metabolismo , Bactérias/metabolismo , Técnicas de Cultura Celular por Lotes , Biomassa , Temperatura Alta , Propionatos/metabolismo
8.
J Appl Microbiol ; 129(3): 509-520, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32167651

RESUMO

AIMS: To evaluate the effects of various epiphytic microbiota from Italian ryegrass (IR), maize (MZ) and sorghum (SG) on fermentative profile and microbial community dynamics in sterile IR. METHODS AND RESULTS: Using microbiota transplantation, the irradiated IR was treated with the following: (i) sterile water; (ii) epiphytic microbiota on IR (IRIR); (iii) epiphytic microbiota on MZ (IRMZ); (iv) epiphytic microbiota on SG (IRSG). After 60 days of ensiling, MZ and SG microbiota significantly (P < 0·05) decreased lactic acid (LA) and acetic acid (AA) concentrations compared to IR microbiota, while SG microbiota notably (P < 0·05) reduced the ratio of LA to AA than MZ and IR microbiota. Apparently (P < 0·01) higher amounts of Lactobacillus genus were observed in IRIR and IRMZ groups on 60 day compared to IRSG group, and the dominant Lactococcus genus on 3 day was eventually replaced by Enterobacteriaceae and Lactobacillus in IRSG group. CONCLUSIONS: Exogenous microbiota could evidently affect the fermentative profile and microbial community dynamics of IR silage. The numbers of Enterobacteriaceae and Lactobacillus were mainly responsible for this. SIGNIFICANCE AND IMPACT OF THE STUDY: Identifying the role of microbe during ensiling is of great significance to manipulate the fermentation products and improve the preservation of silage.


Assuntos
Lolium/microbiologia , Microbiota , Silagem/análise , Silagem/microbiologia , Ácido Acético/metabolismo , Bactérias/classificação , Bactérias/isolamento & purificação , Bactérias/metabolismo , Fermentação , Ácido Láctico/metabolismo , Sorghum/microbiologia , Especificidade da Espécie , Zea mays/microbiologia
9.
Int J Syst Evol Microbiol ; 70(3): 2059-2065, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32100703

RESUMO

An obligately anaerobic, Gram-stain-positive, non-motile and coccoid- or oval-shaped bacterium, designated strain KGMB01111T, was isolated from faeces from a healthy Korean. Comparative analysis of 16S rRNA gene sequences indicated that KGMB01111T was closely related to Ruminococcus gauveauii CCRI-16110T (93.9 %) and Blautia stercoris GAM6-1T (93.7 %), followed by Clostridium nexile DSM 1787T (93.5 %), Blautia producta ATCC 27340T (93.4 %), Blautia hydrogenotrophica DSM 10507T (93.1 %) and Blautia coccoides ATCC 29236T (93.1 %) within the family Lachnospiraceae (Clostridium rRNA cluster XIVa). Phylogenetic analysis based on the 16S rRNA gene sequences indicated that KGMB01111T formed a separate branch with species in the genus Blautia. The major cellular fatty acids (>10.0 %) were C16 : 0 and C18 : 1 cis 9 dimethyl acetal (DMA), and the major polar lipids were aminophospholipids and lipids. KGMB01111T contained meso-diaminopimelic acid in cell-wall peptidoglycan. The predominant end product of fermentation produced by KGMB01111T was acetic acid. Based on the whole-genome sequence, the DNA G+C content of the isolate was 44.7 mol%. On the basis of the phenotypic, chemotaxonomic and phylogenetic characteristics, KGMB01111T represents a novel species within the genus Blautia for which the name Blautia faecicola sp. nov. is proposed. The type strain is KGMB01111T (=KCTC 15706T=DSM 107827T).


Assuntos
Clostridiales/classificação , Fezes/microbiologia , Filogenia , Ácido Acético/metabolismo , Técnicas de Tipagem Bacteriana , Composição de Bases , Clostridiales/isolamento & purificação , DNA Bacteriano/genética , Ácido Diaminopimélico/química , Ácidos Graxos/química , Fermentação , Humanos , Peptidoglicano/química , Fosfolipídeos/química , RNA Ribossômico 16S/genética , República da Coreia , Análise de Sequência de DNA
10.
J Sci Food Agric ; 100(6): 2380-2388, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31901136

RESUMO

BACKGROUND: An imbalanced fat or excess energy intake always results in obesity and increased serum/liver lipids, thus leading to metabolic syndromes. Given the bioactive components in black vinegar (BV), such as branched amino acids, phenolic profile, and mineral contents, we investigated the antiobesity effects of BV-based supplements in rats fed a high-fat diet (HFD). RESULTS: HFD (30% fat, w/w) feeding increased (P < 0.05) body weight, weight gains, weights of livers and mesenteric, epididymal, and perirenal adipose tissues, and serum/liver triglyceride levels relative to those of rats fed a normal diet (4% fat, w/w; CON). These increased values were ameliorated (P < 0.05) by supplementing with BV-based supplements but were still higher (P < 0.05) than those of CON rats. The increased areas of perirenal adipocytes in rats fed with an HFD were also decreased (P < 0.05) by supplementing with BV-based supplements, which might result from an upregulation (P < 0.05) of 5'-adenosine monophosphate-activated protein kinase (AMPK), carnitine palmitoyltransferase-1 (CPT1), and uncoupling protein-2 (UCP2) in the perirenal adipose tissues. A similar effect was observed for AMPK, peroxisome proliferator-activated receptor alpha, retinoid X receptor alpha, CPT1, and UCP2 gene and protein levels in livers (P < 0.05). Generally, BV-based supplements increased the fecal triglyceride, cholesterol, and bile acid levels of rats fed with an HFD, which partially contribute to the lipid-lowering effects. Furthermore, BV-based supplements increased (P < 0.05) hepatic Trolox equivalent antioxidant capacity and lowered (P < 0.05) serum/liver thiobarbituric acid reactive substances values in HFD-fed rats. CONCLUSION: In a chronic high-fat dietary habit, the food-grade BV-based supplement is a good daily choice to ameliorate obesity and its associated comorbidities. © 2020 Society of Chemical Industry.


Assuntos
Ácido Acético/administração & dosagem , Ácido Acético/metabolismo , Fármacos Antiobesidade/farmacologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Adipócitos , Animais , Antioxidantes , Dieta Hiperlipídica/efeitos adversos , Suplementos Nutricionais , Metabolismo Energético , Fezes/química , Masculino , Ratos Wistar
11.
Insect Biochem Mol Biol ; 118: 103312, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31904488

RESUMO

Various insect species including moths have shown significant foraging preference to acetic acid. However, the olfactory reception and behavioral outputs of acetic acid in moths remain unsolved. The female adults of Oriental armyworm, Mythimna separata, exhibit high preference to acetic acid enriched sweet vinegar solutions, making them good targets for exploration of acid reception and performance. We first proved that acetic acid is an essential component which elicited electrophysiological responses from volatiles of the sweet vinegar solution. Successive single sensillum recording tests showed that at least 4 types (as1, as2, as3, and as4) of sensilla were involved in acetic acid reception in the antennae. The low dosages of acetic acid elicited upwind flight and close search, and pre-contact proboscis extension responses of the fasted females, indicating it serves as a food related olfactory cue. In vivo optical imaging data showed that low dosages of acetic acid activated one ordinary glomerulus (DC3), and high dosages evoked additional two glomeruli (DC1 and AC1) in the antennal lobe. A systematic survey on olfaction related receptors in three related transcriptomes has yielded 67 olfactory receptors (ORs) and 19 ionotropic receptors (IRs). Among, MsepIR8a, MsepIR64a, MsepIR75q1, and MsepIR75q2 were chosen as putative acid receptors by blasting against known acid IRs in Drosophila and comparing essential amino acid residues which related to acid sensing. Later in situ hybridization revealed that MsepIr8a was co-expressed with each of the other 3 Irs, suggesting its putative co-receptor role. This study reveals olfactory reception of acetic acid as an attractant in M. separata, and it provides the solid basis for later deorphanization of relevant receptors.


Assuntos
Ácido Acético/metabolismo , Proteínas de Insetos/genética , Mariposas/fisiologia , Percepção Olfatória/genética , Receptores Ionotrópicos de Glutamato/genética , Receptores Odorantes/genética , Olfato , Animais , Feminino , Proteínas de Insetos/metabolismo , Masculino , Mariposas/genética , Receptores Ionotrópicos de Glutamato/metabolismo , Receptores Odorantes/metabolismo
12.
J Environ Sci Health B ; 55(5): 447-454, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31941390

RESUMO

The genome of Acidiphilium multivorum strain AIU 301, acidophilic, aerobic Gram-negative bacteria, was investigated for potential metabolic pathways associated with organic acid production and metal uptake. The genome was compared to other acidic mine drainage isolates, Acidiphilium cryptum JF-5 and Acidithiobacillus ferrooxidans ATCC 23270, as well as Acetobacter pasteurianus 386B, which ferments cocoa beans. Plasmids between two Acidiphilium spp. were compared, and only two of the sixteen plasmids were identified as potentially similar. Comparisons of the genome size to the number of protein coding sequences indicated that A. multivorum and A. cryptum follow the line of best fit unlike A. pasteurianus 386B, which suggests that it was improperly annotated in the database. Pathways between these four species were analyzed bioinformatically and are discussed here. A. multivorum AIU 301, shares pathways with A. pasteurianus 386B including aldehyde and alcohol dehydrogenase pathways, which are used in the generation of vinegar. Mercury reductase, arsenate reductase and sulfur utilization proteins were identified and discussed at length. The absence of sulfur utilization proteins from A. multivorum AIU 301 suggests that this species uses previously undefined pathways for sulfur acquisition. Bioinformatic examination revealed novel pathways that may benefit commercial fields including acetic acid production and biomining.


Assuntos
Ácido Acético/metabolismo , Acidiphilium/genética , Genoma Bacteriano , Acidiphilium/metabolismo , Arseniato Redutases/genética , Biologia Computacional , Simulação por Computador , Tamanho do Genoma , Redes e Vias Metabólicas/genética , Metais/metabolismo , Mineração , Oxirredutases/genética , Plasmídeos , Enxofre/metabolismo
13.
Talanta ; 210: 120679, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31987205

RESUMO

A non-destructive and comprehensive 13C isotopic evaluation approach based on 1H NMR spectroscopy was developed. The carbon isotope distribution (CID) of most of the components (S/N ≥ 1000) in food matrices were evaluated using frequency distribution of peak area ratios (PAR) of decoupling to non-13C-decoupling spectra at natural abundance. The approach was applied successfully to vinegar and it was found that the PAR of fermented vinegars is obviously narrower than that of the blended one and the one produced via chemically defined culture medium. Besides, the extra additives can also be evaluated by their characteristic PAR values. It was found that the sugars are the most commonly added components into the blended vinegars. The results obtained from the developed approach show good validity (baseline effect, RSD < 0.1%) and internal reproducibility (RSD < 0.1%). Practicability of the method is confirmed by gas chromatography-isotope ratio mass spectrometry (GC-IRMS) detection method. The results imply that the proposed approach could be used not only for the discrimination but also for the primary authentication of the blended components in the fermented food matrices.


Assuntos
Ácido Acético/metabolismo , Fermentação , Açúcares/metabolismo , Ácido Acético/química , Isótopos de Carbono , Análise de Alimentos , Açúcares/análise
14.
Food Chem ; 310: 125831, 2020 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-31787391

RESUMO

Two sets of nine ciders were made by cryo-extraction for two consecutive harvests combining three types of ice cider apple juices (mono-varietal, bi-varietal and multi-varietal) and three autochthonous Saccharomyces bayanus yeast strains. The type of juice significantly influenced the pH values and the contents of sorbitol and shikimic acid in the ice juices. The strains used as starters did develop the fermentation producing ciders with alcoholic degrees between 8.75 and 11.52 (% v/v) and volatile acidities lower than 0.55 g acetic acid/L. Regarding the ice ciders, the apple mixture significantly influenced the levels of methanol (higher in mono-varietal ciders), 2-phenylethanol, and some minor acetate esters (higher in the bi-varietal ciders). The last ciders were also more floral, buttery, acidic and bitter than those made from mono- and multi-varietal juices. In the first harvest, the ciders obtained from the bi-varietal apple mixture scored lower for overall sensory quality.


Assuntos
Bebidas Alcoólicas , Malus , Saccharomyces/metabolismo , Ácido Acético/metabolismo , Bebidas Alcoólicas/análise , Fracionamento Químico/métodos , Fermentação , Congelamento , Humanos , Malus/química , Paladar , Compostos Orgânicos Voláteis/análise
15.
Biosci Biotechnol Biochem ; 84(3): 507-517, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31718466

RESUMO

Membrane-bound quinoprotein glucose dehydrogenase from acetic acid bacteria produces lactobionic acid by the oxidation of lactose. Its enzymatic activity on lactose and maltose is much lower than that on D-glucose. For that reason, the activity of the enzyme on disaccharides has been considered low. In this study, we show that the isomaltose-oxidizing activity of acetic acid bacteria is much higher than their lactose-oxidizing activity. In addition to isomaltose, the enzyme oxidized gentiobiose and melibiose to the same extent. According to the characteristics of the isomaltose-oxidizing activity and investigations using dehydrogenase-deficient mutant bacteria, we identified the responsible enzyme as membrane-bound quinoprotein glucose dehydrogenase.Abbreviations: AAB: acetic acid bacteria; m-GDH: membrane-bound quinoprotein glucose dehydrogenase; DCIP: 2,6-dichlorophenolindophenol; DP: degree of polymerization; HPAEC-PAD: high-performance anion-exchange chromatography with pulsed amperometric detection; NMR: nuclear magnetic resonance; TLC: thin layer chromatography; COSY: correlation spectroscopy.


Assuntos
Ácido Acético/metabolismo , Bactérias/metabolismo , Dissacarídeos/metabolismo , Glucose 1-Desidrogenase/metabolismo , Isomaltose/metabolismo , Melibiose/metabolismo , Oxirredução
16.
J Sci Food Agric ; 100(3): 1164-1173, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31680258

RESUMO

BACKGROUND: This study was conducted to analyze the effects of endophytic Bacillus megaterium (BM 18-2) colonization on structure strengthening, microbial community, chemical composition and stabilization properties of Hybrid Pennisetum. RESULTS: The BM 18-2 had successfully colonized in the interior tissues in both leaf and stem of Hybrid Pennisetum. During ensiling, the levels of pH, acetic acid (AA), butyric acid (BA), propionic acid (PA), and the population of yeast and aerobic bacteria were significantly (P > 0.05) lower, while lactic acid bacteria (LAB) and lactic acid (LA) were significantly (P < 0.001) higher with the steps forward of ensiling in with BM 18-2 as compared to without BM 18-2 colonized of Hybrid Pennisetum. During the different ensiling days, at days 3, 6, 15, and 30, the genus Brevundimonas, Klebsiella, Lactococcus, Weissella, Enterobacter, Serratia, etc. population were significantly decreased, while genus Pediococcus acidilactici and Lactobacillus plantarum were significantly influenced in treated groups as compared to control. The genus Lactobacillus and Pediococcus were positively correlated with treatment groups. CONCLUSIONS: It is concluded that the endophytic bacteria strain BM 18-2 significantly promoted growth characteristics and biomass yield before ensiling and after ensiling inoculated with or without Lactobacillus plantarum could improve the distinct changes of the undesirable microbial diversity, chemical composition, and stabilization properties in with BM 18-2 as compared to without BM 18-2 colonized Hybrid Pennisetum. © 2019 Society of Chemical Industry.


Assuntos
Bacillus megaterium/crescimento & desenvolvimento , Endófitos/crescimento & desenvolvimento , Microbiota , Pennisetum/microbiologia , Ácido Acético/metabolismo , Bacillus megaterium/genética , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Ácido Butírico/metabolismo , Endófitos/genética , Ácido Láctico/metabolismo , Pennisetum/genética , Pennisetum/crescimento & desenvolvimento , Leveduras/classificação , Leveduras/genética , Leveduras/isolamento & purificação , Leveduras/metabolismo
17.
Arch Anim Nutr ; 74(2): 150-163, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31851529

RESUMO

The study investigated the production of volatile organic compounds during the fermentation of maize containing 26.8% dry matter (DM). Forage was ensiled without additive or treated with 2 ml/kg of a chemical silage additive (SA) containing per litre 257 g sodium benzoate, 134 g potassium sorbate and 57 g ammonium propionate, and either sealed immediately or with a delay of 24 h. During the fermentation process, DM-losses, fermentation pattern (including ethyl lactate [EL] and ethyl acetate [EA]) and yeast numbers were determined. Delayed sealing and no SA resulted in highest DM losses with significant interactions between sealing time (ST) and SA on all sampling days (p < 0.001). The effects on organic acid production were variable depending on storage length. Ethanol production was affected by ST and SA, but promptly sealed silage treated with SA had consistently the lowest concentrations. Higher ethanol content during fermentation was associated with higher DM losses, as reflected by a strongly linear, positive relationship (R2 = 0.70, p < 0.001). Compared with promptly sealed silage, the counts of yeasts were higher after delayed sealing during the first 7 d of storage (p < 0.001). Moreover, SA reduced yeast numbers compared with untreated silage (p < 0.01). EL concentrations increased throughout storage, whereas EA acetate accumulation was very rapid and intense already during the early stages of fermentation and peaked on d 34. The differences in concentrations and accumulation pattern between EL and EA, especially during the early fermentation phases, make evident that their synthesis was facilitated by different pathways and reactions, respectively.


Assuntos
Ésteres/metabolismo , Fermentação , Silagem/análise , Compostos Orgânicos Voláteis/agonistas , Leveduras/metabolismo , Zea mays/química , Ácido Acético/metabolismo , Etanol/metabolismo , Ácido Láctico/metabolismo
18.
Food Chem ; 302: 125335, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31416001

RESUMO

Cocoa bean fermentation still remains a rather empirical process. The research presented here employed an artificial system of fermentation, using controlled incubations, in order to achieve greater control over the external influences that cocoa beans are exposed to, with the aim of experimentally modelling changes to bean components (responses). Experimental design was used, in a first-ever attempt, to study the effects of five factors and their interactions on the profiles of pH, peptides, and flavanols in the bean during the incubations. Temperature, incubation time and the concentration of acetic acid were the main factors influencing the three responses. Moreover, there was a significant amount of factor interaction, revealing the process to be more complex than initially thought, especially with respect to the role of ethanol. Using the model, one was also able to accurately predict the response of the bean to the exposure to specific factors.


Assuntos
Cacau/metabolismo , Indústria de Processamento de Alimentos/métodos , Modelos Teóricos , Ácido Acético/metabolismo , Cacau/química , Etanol/metabolismo , Fermentação , Concentração de Íons de Hidrogênio , Ácido Láctico/metabolismo , Reprodutibilidade dos Testes , Temperatura
19.
Biosci Biotechnol Biochem ; 84(4): 832-841, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31851582

RESUMO

Thermotolerant strains are critical for low-cost high temperature fermentation. In this study, we carried out the thermal adaptation of A. pasteurianus IFO 3283-32 under acetic acid fermentation conditions using an experimental evolution approach from 37ºC to 40ºC. The adapted strain exhibited an increased growth and acetic acid fermentation ability at high temperatures, however, with the trade-off response of the opposite phenotype at low temperatures. Genome analysis followed by PCR sequencing showed that the most adapted strain had 11 mutations, a single 64-kb large deletion, and a single plasmid loss. Comparative phenotypic analysis showed that at least the large deletion (containing many ribosomal RNAs and tRNAs genes) and a mutation of DNA polymerase (one of the 11 mutations) critically contributed to this thermotolerance. The relationship between the phenotypic changes and the gene mutations are discussed, comparing with another thermally adapted A. pasteurianus strains obtained previously.


Assuntos
Acetobacter/fisiologia , Evolução Molecular , Genoma Bacteriano , Termotolerância , Ácido Acético/metabolismo , Acetobacter/genética , Acetobacter/metabolismo , Fermentação , Mutação
20.
J Dairy Sci ; 103(1): 379-395, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31629529

RESUMO

Dairy farmers are often challenged with the need to feed high-moisture corn (HMC) after less than 30 d of fermentation. The objective this study was to assess the effects of microbial inoculation and particle size on fermentation profile, aerobic stability, and ruminal in situ starch degradation of HMC ensiled for a short period. High-moisture corn was harvested, coarsely ground (3,798 ± 40 µm, on average) or finely ground (984 ± 42 µm, on average), then ensiled in quadruplicate vacuum pouches untreated (CON) or with the following treatments: Lactobacillus plantarum CH6072 at 5 × 104 cfu/g and Enterococcus faecium CH212 at 5 × 104 cfu/g of fresh forage (LPEF); or Lactobacillus buchneri LB1819 at 7.5 × 104 cfu/g and Lactococcus lactis O224 at 7.5 × 104 cfu/g (LBLL). Silos were allowed to ferment for 14 or 28 d. Ruminal in situ starch degradation increased when HMC was finely ground. In addition, in situ starch degradation was greater and aerobic stability increased approximately 5-fold with LBLL compared with CON and LPEF. An interaction between microbial inoculation and storage length occurred for lactic acid. At 14 d, concentrations of lactic acid were greatest in LPEF and lowest in LBLL. Lactic acid concentrations increased from 14 to 28 d with CON and LPEF, but decreased with LBLL. At 28 d, concentrations of lactic acid were lower in LBLL compared with CON and LPEF. An interaction between particle size, microbial inoculation, and storage length occurred for acetic acid and ammonia-N. At 14 and 28 d, acetic acid concentrations were greatest in finely ground LBLL followed by coarsely ground LBLL. Ammonia-N concentrations increased across all treatments from 0 to 28 d. At 14 and 28 d, concentrations of ammonia-N were greatest in finely ground LBLL and lowest in coarsely ground CON and coarsely ground LPEF. Results from this study suggest that L. buchneri LB1819 can produce acetic acid in as little as 14 d, and that by 28 d, it has the potential to improve the aerobic stability of HMC. Additionally, results indicate that L. buchneri LB1819 has the potential to improve ruminal degradation of starch by 28 d of storage. Finally, results confirm enhanced fermentation and improved ruminal starch degradation with finely ground HMC by 28 d of storage.


Assuntos
Enterococcus faecium/fisiologia , Lactobacillus/fisiologia , Silagem/análise , Amido/metabolismo , Zea mays , Ácido Acético/metabolismo , Aerobiose , Inoculantes Agrícolas , Animais , Fermentação , Lactobacillus/classificação , Tamanho da Partícula , Silagem/microbiologia , Amido/química , Zea mays/metabolismo , Zea mays/microbiologia
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