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1.
Biomacromolecules ; 25(3): 2024-2032, 2024 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-38393758

RESUMO

α-Glucan microparticles (GMPs) have significant potential as high-value biomaterials in various industries. This study proposes a bottom-up approach for producing GMPs using four amylosucrases from Bifidobacterium sp. (BASs). The physicochemical characteristics of these GMPs were analyzed, and the results showed that the properties of the GMPs varied depending on the type of enzymes used in their synthesis. As common properties, all GMPs exhibited typical B-type crystal patterns and poor colloidal dispersion stability. Interestingly, differences in the physicochemical properties of GMPs were generated depending on the synthesis rate of linear α-glucan by the enzymes and the degree of polymerization (DP) distribution. Consequently, we found differences in the properties of GMPs depending on the DP distribution of linear glucans prepared with four BASs. Furthermore, we suggest that precise control of the type and characteristics of the enzymes provides the possibility of producing GMPs with tailored physicochemical properties for various industrial applications.


Assuntos
Bifidobacterium , Glucanos , Guanosina Monofosfato , Tionucleotídeos , Glucanos/química , Glucosiltransferases
2.
World J Microbiol Biotechnol ; 40(9): 261, 2024 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-38972914

RESUMO

The fecal microbiota of two healthy adults was cultivated in a medium containing commercial fructooligosaccharides [FOS; 1-kestose (GF2), nystose (GF3), and 1F-fructofuranosylnystose (GF4)]. Initially, the proportions of lactobacilli in the two feces samples were only 0.42% and 0.17%; however, they significantly increased to 7.2% and 4.8%, respectively, after cultivation on FOS. Most FOS-utilizing isolates could utilize only GF2; however, Lacticaseibacillus paracasei strain Lp02 could fully consume GF3 and GF4 too. The FOS operon (fosRABCDXE) was present in Lc. paracasei Lp02 and another Lc. paracasei strain, KCTC 3510T, but fosE was only partially present in the non-FOS-degrading strain KCTC 3510T. In addition, the top six upregulated genes in the presence of FOS were fosABCDXE, particularly fosE. FosE is a ß-fructosidase that hydrolyzes both sucrose and all three FOS. Finally, a genome-based analysis suggested that fosE is mainly observed in Lc. paracasei, and only 13.5% (61/452) of their reported genomes were confirmed to include it. In conclusion, FosE allows the utilization of FOS, including GF3 and GF4 as well as GF2, by some Lc. paracasei strains, suggesting that this species plays a pivotal role in FOS utilization in the human gut.


Assuntos
Fezes , Microbioma Gastrointestinal , Lacticaseibacillus paracasei , Oligossacarídeos , beta-Frutofuranosidase , Humanos , Oligossacarídeos/metabolismo , Fezes/microbiologia , Lacticaseibacillus paracasei/metabolismo , Lacticaseibacillus paracasei/genética , beta-Frutofuranosidase/metabolismo , beta-Frutofuranosidase/genética , Adulto , Óperon , Trissacarídeos/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo
3.
Genomics ; 113(1 Pt 2): 647-653, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33010389

RESUMO

1-Deoxynojirumycin (1-DNJ) is a representative iminosugar with α-glucosidase inhibition (AGI) activity. In this study, the full genome sequencing of 1-DNJ-producing Bacillus velezensis K26 was performed. The genome consists of a circular chromosome (4,047,350 bps) with two types of putative virulence factors, five antibiotic resistance genes, and seven secondary metabolite biosynthetic gene clusters. Genomic analysis of a wide range of Bacillus species revealed that a 1-DNJ biosynthetic gene cluster was commonly present in four Bacillus species (B. velezensis, B. pseudomycoides, B. amyloliquefaciens, and B. atrophaeus). In vitro experiments revealed that the increased mRNA expression levels of the three 1-DNJ biosynthetic genes were closely related to increased AGI activity. Genomic comparison and alignment of multiple gene sequences indicated the conservation of the 1-DNJ biosynthetic gene cluster in each Bacillus species. This genomic analysis of Bacillus species having a 1-DNJ biosynthetic gene cluster could provide a basis for further research on 1-DNJ-producing bacteria.


Assuntos
Bacillus/genética , Genes Bacterianos , Glucosamina/análogos & derivados , 1-Desoxinojirimicina , Bacillus/classificação , Bacillus/metabolismo , Glucosamina/biossíntese , Glucosamina/genética , Família Multigênica , Filogenia , Homologia de Sequência
4.
Curr Microbiol ; 77(8): 1839-1847, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32166413

RESUMO

Pectin exists in significant amounts in vegetables and fruits as a component of the plant cell wall. In human diet, pectin is not degraded by the human digestive enzymes due to its complex structure; only gut bacteria degrade pectin in the large intestine. To date, although pectin is one of the most important sources of dietary fiber in human diet, there have been only few reports on human gut-originated pectinolytic bacteria. In this study, the strain Enterococcus mundtii Pe103, a bacterium with pectin-degrading activity, was isolated from the feces of a healthy Korean adult female. Culture experiments revealed that it could grow on pectin as the sole carbon source by degrading pectin to approximately 35% within 13 h. We report the complete genome data of human gut E. mundtii Pe103. It consists of a circular chromosome (3,084,146 bps) and two plasmids (63,713 and 56,223 bps). Genomic analysis suggested that at least nine putative enzymes related to pectin degradation are present in E. mundtii Pe103. These enzymes may be involved in the degradation of pectin. The whole genome information of E. mundtii Pe103 could improve the understanding of the mechanism underlying the degradation of pectin by human gut microbiota.


Assuntos
Enterococcus/enzimologia , Enterococcus/genética , Microbioma Gastrointestinal , Genoma Bacteriano , Pectinas/metabolismo , Adulto , Fibras na Dieta/metabolismo , Enterococcus/isolamento & purificação , Fezes/microbiologia , Feminino , Humanos
5.
Molecules ; 25(1)2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31906359

RESUMO

Isoflavones in soybeans are well-known phytoestrogens. Soy isoflavones present in conjugated forms are converted to aglycone forms during processing and storage. Isoflavone aglycones (IFAs) of soybeans in human diets have poor solubility in water, resulting in low bioavailability and bioactivity. Enzyme-mediated glycosylation is an efficient and environmentally friendly way to modify the physicochemical properties of soy IFAs. In this study, we determined the optimal reaction conditions for Deinococcus geothermalis amylosucrase-mediated α-1,4 glycosylation of IFA-rich soybean extract to improve the bioaccessibility of IFAs. The conversion yields of soy IFAs were in decreasing order as follows: genistein > daidzein > glycitein. An enzyme quantity of 5 U and donor:acceptor ratios of 1000:1 (glycitein) and 400:1 (daidzein and genistein) resulted in high conversion yield (average 95.7%). These optimal reaction conditions for transglycosylation can be used to obtain transglycosylated IFA-rich functional ingredients from soybeans.


Assuntos
Deinococcus/enzimologia , Glucosiltransferases/metabolismo , Glycine max/química , Isoflavonas/química , Extratos Vegetais/química , beta-Glucanas/química , Disponibilidade Biológica , Cromatografia Líquida de Alta Pressão , Escherichia coli/genética , Vetores Genéticos , Genisteína/química , Glucosiltransferases/genética , Glicosilação , Isoflavonas/biossíntese , Isoflavonas/isolamento & purificação , Isoflavonas/farmacocinética , Espectrometria de Massas , Fitoestrógenos/química , Extratos Vegetais/isolamento & purificação , beta-Glucanas/farmacocinética
6.
Curr Microbiol ; 76(9): 995-1002, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31177311

RESUMO

Strain MBLB1234T was isolated from bentonite samples collected at Guryong mining area located in Pohang, Republic of Korea and was taxonomically characterized by a polyphasic approach. This strain was a Gram-stain-negative, motile, endospore-forming, facultative anaerobic, catalase-positive, oxidase-negative, and rod-shaped bacterium. Strain MBLB1234T was able to grow at 20‒45 °C (optimum, 37 °C), pH 6.0‒10.0 (optimum, 7.0-8.0), and 0‒5.0% (w/v) NaCl (optimum, 0.5%). Genome size was 6,497,679 bp with a G + C content of 46.4 mol %. The genome was predicted to contain 5233 protein-coding genes, and 135 rRNA genes consisted of 10 5S rRNAs, 10 16S rRNAs, 10 23S rRNAs, and 105 tRNAs. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that strain MBLB1234T clustered with Paenibacillus motobuensis JCM 12774T and P. aceti JCM 31170T with 98.3-98.5% and 97.2-97.4% sequencing similarity, respectively. The major fatty acids of strain MBLB1234T were anteiso-C15:0 (35.7%), anteiso-C17:0 (17.8%), iso-C17:0 (14.5%), and C16:0 (11.0%). The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine, and one unidentified phospholipid, six unidentified aminophospholipids, and one unidentified lipid. The predominant isoprenoid quinone was menaquinone-7. DNA-DNA hybridization values between strain MBLB1234T and P. motobuensis JCM 12774T and P. aceti JCM 31170T were 34 and 38%, respectively. Average nucleotide identity value between strains MBLB1234T and P. aceti L14T was 82.3%. Based on characteristics of genomic, phenotypic, chemotaxonomic, and phylogenetic analyses, strain MBLB1234T represents a novel species of the genus P. , for which the name P. lutimineralis sp. nov. is proposed. The type strain is MBLB1234T (= JCM 32684T = KCTC 33978T).


Assuntos
Sedimentos Geológicos/microbiologia , Paenibacillus/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , Bentonita/análise , DNA Bacteriano/genética , Ácidos Graxos/química , Ácidos Graxos/metabolismo , Sedimentos Geológicos/análise , Mineração , Paenibacillus/classificação , Paenibacillus/genética , Paenibacillus/metabolismo , Filogenia , RNA Ribossômico 16S/genética , República da Coreia
7.
Food Microbiol ; 77: 166-172, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30297047

RESUMO

Microbial spoilage is a complex event to which different bacterial populations and metabolites can contribute depending on the storage conditions. This study explored the evolution of spoilage and related volatile organic compounds (VOCs) in chilled beef under air and vacuum packaging (VP). The results suggested that different storage conditions affected changes in bacterial communities and metabolites in beef and consequently affected the odor properties of the stored beef, thereby leading to spoilage. Bacterial species belonging to Pseudomonadaceae (Pseudomonas spp.) and lactic acid bacteria (Lactobacillus sp.) dominated the bacterial communities in beef stored under air and VP, respectively, with several VOCs associated with off-odors of the stored beef and most likely produced by both bacteria. Our results suggested several microbial VOCs that could be used as potential spoilage indicators, including acetic acid, butanoic acid, and 2-butanone in VP-stored beef and 3-methylbutan-1-ol, ethyl acetate, acetoin, 2-butanone, and diacetyl in air-stored beef. These findings might provide valuable information regarding the quality monitoring of beef during storage.


Assuntos
Bactérias/classificação , Bactérias/metabolismo , Temperatura Baixa , Microbiologia de Alimentos , Embalagem de Alimentos/métodos , Microbiota , Carne Vermelha/microbiologia , Ar , Animais , Bactérias/crescimento & desenvolvimento , Biodiversidade , Bovinos , Contagem de Colônia Microbiana , Armazenamento de Alimentos , Lactobacillus/crescimento & desenvolvimento , Lactobacillus/metabolismo , Odorantes/análise , Pseudomonadaceae/crescimento & desenvolvimento , Pseudomonadaceae/metabolismo , Vácuo , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/metabolismo
8.
Appl Microbiol Biotechnol ; 102(11): 4927-4936, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29654556

RESUMO

Resistant starch (RS) in the diet reaches the large intestine without degradation, where it is decomposed by the commensal microbiota. The fermentation of RS produces secondary metabolites including short-chain fatty acids (SCFAs), which have been linked to a variety of physiological and health effects. Therefore, the availability of RS as a prebiotic is a current issue. The objectives of this study were (1) to use metagenomics to observe microbial flora changes in Bos taurus coreanae rumen fluid in the presence of RS and (2) to isolate RS-degrading microorganisms. The major microbial genus in a general rumen fluid was Succiniclasticum sp., whereas Streptococcus sp. immediately predominated after the addition of RS into the culture medium and was then drastically replaced by Lactobacillus sp. The presence of Bifidobacterium sp. was also observed continuously. Several microorganisms with high RS granule-degrading activity were identified and isolated, including B. choerinum FMB-1 and B. pseudolongum FMB-2. B. choerinum FMB-1 showed the highest RS-hydrolyzing activity and degraded almost 60% of all substrates tested. Coculture experiments demonstrated that Lactobacillus brevis ATCC 14869, which was isolated from human feces, could grow using reducing sugars generated from RS by B. choerinum FMB-1. These results suggest that Bifidobacterium spp., especially B. choerinum FMB-1, are the putative primary degrader of RS in rumen microbial flora and could be further studied as probiotic candidates.


Assuntos
Microbioma Gastrointestinal/efeitos dos fármacos , Rúmen/microbiologia , Amido/metabolismo , Amido/farmacologia , Animais , Bactérias/isolamento & purificação , Bactérias/metabolismo , Bovinos , Fezes/microbiologia , Fermentação , Humanos
9.
World J Microbiol Biotechnol ; 34(3): 44, 2018 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-29500614

RESUMO

A putative gene (gadlbhye1) encoding glutamate decarboxylase (GAD) was cloned from Lactobacillus brevis HYE1 isolated from kimchi, a traditional Korean fermented vegetable. The amino acid sequences of GADLbHYE1 showed 48% homology with the GadA family and 99% identity with the GadB family from L. brevis. The cloned GADLbHYE1 was functionally expressed in Escherichia coli using inducible expression vectors. The expressed recombinant GADLbHYE1 was successfully purified by Ni-NTA affinity chromatography, and had a molecular mass of 54 kDa with optimal hydrolysis activity at 55 °C and pH 4.0. Its thermal stability was determined to be higher than that of other GADs from L. brevis, based on its melting temperature (75.18 °C). Kinetic parameters including Km and Vmax values for GADLbHYE1 were 4.99 mmol/L and 0.224 mmol/L/min, respectively. In addition, the production of gamma-aminobutyric acid in E. coli BL21 harboring gadlbhye1/pET28a was increased by adding pyridoxine as a cheaper coenzyme.


Assuntos
Alimentos Fermentados/microbiologia , Glutamato Descarboxilase/biossíntese , Glutamato Descarboxilase/química , Glutamato Descarboxilase/genética , Levilactobacillus brevis/enzimologia , Levilactobacillus brevis/genética , Levilactobacillus brevis/isolamento & purificação , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Clonagem Molecular , Coenzimas/metabolismo , Estabilidade Enzimática , Escherichia coli/genética , Fermentação , Regulação Bacteriana da Expressão Gênica , Concentração de Íons de Hidrogênio , Cinética , Peso Molecular , Piridoxina/metabolismo , Proteínas Recombinantes/genética , Alinhamento de Sequência , Análise de Sequência , Temperatura , Ácido gama-Aminobutírico/biossíntese
10.
Asian-Australas J Anim Sci ; 31(8): 1358-1365, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29381898

RESUMO

OBJECTIVE: The effect of pre-converted nitrites from natural sources (spinach, lettuce, celery, and red beet) on color development in raw and cooked pork sausage was investigated in this study. METHODS: The pork sausage was manufactured with six treatments: NC (negative control, nitrite free), PC (positive control, 150 ppm sodium nitrite), FS (3.0% fermented spinach extracts), FL (3.0% fermented lettuce extracts), FC (3.0% fermented celery extracts), and FR (3.0% fermented red beet extracts). RESULTS: The pH value of the pre-converted nitrites groups was lower than those treated with 150 ppm sodium nitrite (p<0.05). The color values of raw and cooked pork sausage added with pre-converted nitrite showed slightly lower and/or similar lightness, lower redness, and higher yellowness values than PC. Color development (redness values) of cooked samples added with FS was higher than those of the NC and other treatments (FL, FC, and FR). Additionally, treatments with FS and FL were most effective for reducing thiobarbituric acid reactive substances and volatile basic nitrogen than the NC. CONCLUSION: Effects of natural nitrites from fermented vegetables on shelf stability of raw and cooked pork sausages were investigated. Fermented spinach extract was much more useful for maintaining the color development, but also inhibiting lipid and protein oxidation of cooked pork sausage. Therefore, pre-converted nitrite from spinach as a natural nitrite could be used as another natural nitrite source for making processed meat products.

11.
Biochem Biophys Res Commun ; 483(1): 115-121, 2017 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-28042032

RESUMO

Among members of the glycoside hydrolase (GH) family, sucrose isomerase (SIase) and oligo-1,6-glucosidase (O16G) are evolutionarily closely related even though their activities show different specificities. A gene (Avin_08330) encoding a putative SIase (AZOG: Azotobacterglucocosidase) from the nitrogen-fixing bacterium Azotobacter vinelandii is a type of pseudo-SIase harboring the "RLDRD" motif, a SIase-specific region in 329-333. However, neither sucrose isomerization nor hydrolysis activities were observed in recombinant AZOG (rAZOG). The rAZOG showed similar substrate specificity to Bacillus O16G as it catalyzes the hydrolysis of isomaltulose and isomaltose, which contain α-1,6-glycosidic linkages. Interestingly, rAZOG could generate isomaltose from the small substrate methyl-α-glucoside (MαG) via intermolecular transglycosylation. In addition, sucrose isomers isomaltulose and trehalulose were produced when 250 mM fructose was added to the MαG reaction mixture. The conserved regions I and II of AZOG are shared with many O16Gs, while regions III and IV are very similar to those of SIases. Strikingly, a shuffled AZOG, in which the N-terminal region of SIase containing conserved regions I and II was exchanged with the original enzyme, exhibited a production of sucrose isomers. This study demonstrates an evolutionary relationship between SIase and O16G and suggests some of the main regions that determine the specificity of SIase and O16G.


Assuntos
Azotobacter vinelandii/enzimologia , Proteínas de Bactérias/metabolismo , Glucosiltransferases/metabolismo , Motivos de Aminoácidos , Azotobacter vinelandii/genética , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Biotecnologia , Domínio Catalítico , Sequência Conservada , Dissacarídeos/metabolismo , Evolução Molecular , Genes Bacterianos , Variação Genética , Glucosiltransferases/química , Glucosiltransferases/genética , Isomaltose/análogos & derivados , Isomaltose/metabolismo , Modelos Moleculares , Oligo-1,6-Glucosidase/química , Oligo-1,6-Glucosidase/genética , Oligo-1,6-Glucosidase/metabolismo , Filogenia , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Homologia de Sequência de Aminoácidos , Especificidade por Substrato , Sacarose/metabolismo
12.
Anal Biochem ; 532: 19-25, 2017 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-28577993

RESUMO

The purpose of this study was to investigate the novel fluorescence-based assay for the transglycosylation activity of amylosucrase (ASase). The transglycosylation activity of ASase from Deinococcus geothermalis (DGAS), ASase from Neisseria polysaccharea (NPAS), and DGAS-B (chimeric ASase wherein the B domain from DGAS was exchanged with the B domain of NPAS in a DGAS background) was applied to modify 4-methlylumberlliferone (MU) to 4-methylumberlliferone glucoside (MUG) using MU as an acceptor and sucrose as a glucoside donor. The result of HPLC (high performance liquid chromatography) show that the bioconversion of MUG with ASases was successfully accomplished using sucrose and MU. Kinetic studies of ASases were performed to determine kinetic parameter for sucrose and MU. The order of overall performance (kcat/Km) of transglycosylation activity for MU among DGAS, DGAS-B and NPAS was as follows: DGAS-B (8.1) > DGAS (5.0) > NPAS (0.4). The fluorescence-based transglycosylation assay using MU has a potential to be used as the detection of transglycosylation activity of ASase and to screen novel ASase variants, which may be improved in their transglycosylation activities.


Assuntos
Proteínas de Bactérias/metabolismo , Deinococcus/enzimologia , Glucosiltransferases/metabolismo , Neisseria/enzimologia , Sacarose/metabolismo , Cromatografia Líquida de Alta Pressão , Fluorescência , Glicosilação , Cinética
13.
J Bacteriol ; 196(5): 1122-31, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24391053

RESUMO

A unique gene cluster responsible for kojibiose utilization was identified in the genome of Pyrococcus sp. strain ST04. The proteins it encodes hydrolyze kojibiose, a disaccharide product of glucose caramelization, and form glucose-6-phosphate (G6P) in two steps. Heterologous expression of the kojibiose-related enzymes in Escherichia coli revealed that two genes, Py04_1502 and Py04_1503, encode kojibiose phosphorylase (designated PsKP, for Pyrococcus sp. strain ST04 kojibiose phosphorylase) and ß-phosphoglucomutase (PsPGM), respectively. Enzymatic assays show that PsKP hydrolyzes kojibiose to glucose and ß-glucose-1-phosphate (ß-G1P). The Km values for kojibiose and phosphate were determined to be 2.53 ± 0.21 mM and 1.34 ± 0.04 mM, respectively. PsPGM then converts ß-G1P into G6P in the presence of 6 mM MgCl2. Conversion activity from ß-G1P to G6P was 46.81 ± 3.66 U/mg, and reverse conversion activity from G6P to ß-G1P was 3.51 ± 0.13 U/mg. The proteins are highly thermostable, with optimal temperatures of 90°C for PsKP and 95°C for PsPGM. These results indicate that Pyrococcus sp. strain ST04 converts kojibiose into G6P, a substrate of the glycolytic pathway. This is the first report of a disaccharide utilization pathway via phosphorolysis in hyperthermophilic archaea.


Assuntos
Proteínas Arqueais/metabolismo , Dissacarídeos/metabolismo , Regulação da Expressão Gênica em Archaea/fisiologia , Pyrococcus/metabolismo , Proteínas Arqueais/genética , Clonagem Molecular , Dados de Sequência Molecular , Pyrococcus/genética , Especificidade por Substrato
14.
Anal Biochem ; 444: 75-80, 2014 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-24096132

RESUMO

A simple, inexpensive, and universal method to quantify the recombinant proteins in Escherichia coli cell lysate using differential scanning fluorimetry (DSF) is reported. This method is based on the precise correlation between Δ(fluorescence intensity) determined by DSF and the amount of protein in solution. We first demonstrated the effectiveness of the DSF method using two commercially available enzymes, α-amylase and cellobiase, and then confirmed its utility with two recombinant proteins, amylosucrase and maltogenic amylase, expressed in E. coli. The Δ(fluorescence intensity) in DSF analysis accurately correlated with the concentration of the purified enzymes as well as the recombinant proteins in E. coli cell lysates. The main advantage of this method over other techniques such as Western blotting, enzyme-linked immunosorbent assay (ELISA), and green fluorescence protein (GFP) fusion proteins is that intact recombinant protein can be quantified without the requirement of additional chemicals or modifications of the recombinant protein. This DSF assay can be performed using widely available equipment such as a real-time polymerase chain reaction (RT-PCR) instrument, microplates or microtubes, and fluorescent dye. This simple but powerful method can be easily applied in a wide range of research areas that require quantification of expressed recombinant proteins.


Assuntos
Extratos Celulares/química , Fluorometria/métodos , Proteínas Recombinantes/análise , Escherichia coli/citologia , Escherichia coli/metabolismo
15.
Appl Microbiol Biotechnol ; 98(5): 2121-31, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23884203

RESUMO

The deduced amino acid sequence from a gene of the hyperthermophilic archaeon Pyrococcus sp. ST04 (Py04_0872) contained a conserved glycoside hydrolase family 57 (GH57) motif, but showed <13% sequence identity with other known Pyrococcus GH57 enzymes, such as 4-α-glucanotransferase (EC 2.4.1.25), amylopullulanase (EC 3.2.1.41), and branching enzyme (EC 2.4.1.18). This gene was cloned and expressed in Escherichia coli, and the recombinant product (Pyrococcus sp. ST04 maltose-forming α-amylase, PSMA) was a novel 70-kDa maltose-forming α-amylase. PSMA only recognized maltose (G2) units with α-1,4 and α-1,6 linkages in polysaccharides (e.g., starch, amylopectin, and glycogen) and hydrolyzed pullulan very poorly. G2 was the primary end product of hydrolysis. Branched cyclodextrin (CD) was only hydrolyzed along its branched maltooligosaccharides. 6-O-glucosyl-ß-cyclodextrin (G1-ß-CD) and ß-cyclodextrin (ß-CD) were resistant to PSMA suggesting that PSMA is an exo-type glucan hydrolase with α-1,4- and α-1,6-glucan hydrolytic activities. The half-saturation value (Km) for the α-1,4 linkage of maltotriose (G3) was 8.4 mM while that of the α-1,6 linkage of 6-O-maltosyl-ß-cyclodextrin (G2-ß-CD) was 0.3 mM. The kcat values were 381.0 min(-1) for G3 and 1,545.0 min(-1) for G2-ß-CD. The enzyme was inhibited competitively by the reaction product G2, and the Ki constant was 0.7 mM. PSMA bridges the gap between amylases that hydrolyze larger maltodextrins and α-glucosidase that feeds G2 into glycolysis by hydrolyzing smaller glucans into G2 units.


Assuntos
Maltose/metabolismo , Pyrococcus/enzimologia , alfa-Amilases/isolamento & purificação , alfa-Amilases/metabolismo , Clonagem Molecular , Escherichia coli/genética , Expressão Gênica , Cinética , Peso Molecular , Pyrococcus/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Especificidade por Substrato , alfa-Amilases/química , alfa-Amilases/genética
16.
Int J Biol Macromol ; 273(Pt 2): 133205, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38885871

RESUMO

Although myricetin (3,3',4',5,5',7-hexahydroxyflavone, MYR) has a high antioxidant capacity and health functions, its use as a functional food material is limited owing to its low stability and water solubility. Amylosucrase (ASase) is capable of biosynthesizing flavonol α-glycoside using flavonols as acceptor molecules and sucrose as a donor molecule. Here, ASase from Deinococcus deserti (DdAS) efficiently biosynthesizes a novel MYR α-triglucoside (MYRαG3) using MYR as the acceptor molecule. Comparative homology analysis and computational simulation revealed that DdAS has a different active pocket for the transglycosylation reaction. DdAS produced MYRαG3 with a conversion efficiency of 67.4 % using 10 mM MYR and 50 mM sucrose as acceptor and donor molecules, respectively. The structure of MYRαG3 was identified as MYR 4'-O-4″,6″-tri-O-α-D-glucopyranoside using NMR and LC-MS. In silico analysis confirmed that DdAS has a distinct active pocket compared to other ASases. In addition, molecular docking simulations predicted the synthetic sequence of MYRαG3. Furthermore, MYRαG3 showed a similar DPPH radical scavenging activity of 49 %, comparable to MYR, but with significantly higher water solubility, which increased from 0.03 µg/mL to 511.5 mg/mL. In conclusion, this study demonstrated the efficient biosynthesis of a novel MYRαG3 using DdAS and highlighted the potential of MYRαG3 as a functional material.


Assuntos
Deinococcus , Flavonoides , Glucosídeos , Glucosiltransferases , Solubilidade , Deinococcus/enzimologia , Glucosiltransferases/química , Glucosiltransferases/metabolismo , Flavonoides/química , Flavonoides/metabolismo , Flavonoides/biossíntese , Glucosídeos/química , Glucosídeos/biossíntese , Glucosídeos/metabolismo , Antioxidantes/química , Antioxidantes/metabolismo , Simulação de Acoplamento Molecular
17.
Food Sci Biotechnol ; 33(9): 2047-2064, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-39130663

RESUMO

Alternative sugars are often used as sugar substitutes because of their low calories and glycemic index. Recently, consumption of these sweeteners in diet foods and beverages has increased dramatically, raising concerns about their health effects. This review examines the types and characteristics of artificial sweeteners and rare sugars and analyzes their impact on the gut microbiome. In the section on artificial sweeteners, we have described the chemical structures of different sweeteners, their digestion and absorption processes, and their effects on the gut microbiota. We have also discussed the biochemical properties and production methods of rare sugars and their positive and negative effects on gut microbial communities. Finally, we have described how artificial sweeteners and rare sugars alter the gut microbiome and how these changes affect the gut environment. Our observations aim to improve our understanding regarding the potential health implications of the consumption of artificial sweeteners and low-calorie sugars.

18.
Food Chem ; 460(Pt 3): 140804, 2024 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-39137578

RESUMO

Here, we investigated the complexation of short chain amylose (SCAs) and palmitic acid (PA), serving as polymeric building blocks that alter the selectivity and directionality of particle growth. This alteration affects the shape anisotropy of the particles, broadening their applications due to the increased surface area. By modifying the concentration of PA, we were able to make spherical, macaron, and disc-shaped particles, demonstrating that PA acts as a structure-directing agent. We further illustrated the lateral and longitudinal stacking kinetics between PA-SCA inclusion complexes during self-assembly, leading to anisotropy. Transmission electron microscope (TEM) and scanning electron microscope (SEM) revealed the structural difference between the initial and final morphologies of palmitic acid-short chain amylose particles (PA-SCAPs) compared to those of short-chain amylose particle (SCAPs). The presence of PA-SCA inclusion complex in the anisotropic particles was confirmed using nuclear magnetic resonance (NMR) and powder x-ray diffraction (XRD) analysis.


Assuntos
Amilose , Cristalização , Ácido Palmítico , Tamanho da Partícula , Amilose/química , Ácido Palmítico/química , Cinética , Difração de Raios X
19.
Int J Biol Macromol ; 269(Pt 2): 131834, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38688341

RESUMO

The amylosucrase (ASase, EC 2.4.1.4) utilizes sucrose as the sole substrate to catalyze multifunctional reactions. It can naturally synthesize α-1,4-linked glucans such as amylose as well as sucrose isomers with more favorable properties than sucrose with a lower intestinal digestibility and non-cariogenic properties. The amino acid sequence of the asase gene from Deinococcus cellulosilyticus (DceAS) exhibits low homology with those of other ASases from other Deinococcus species. In this study, we cloned and expressed DceAS and demonstrated its high activity at pH 6 and pH 8 and maintained stability. It showed higher polymerization activity at pH 6 than at pH 8, but similar isomerization activity and produced more turanose and trehalulose at pH 6 than at pH 8 and produced more isomaltulose at pH 8. Furthermore, the molecular weight of DceAS was 226.6 kDa at pH 6 and 145.5 kDa at pH 8, indicating that it existed as a trimer and dimer, respectively under those conditions. Additionally, circular dichroism spectra showed that the DceAS secondary structure was different at pH 6 and pH 8. These differences in reaction products at different pHs can be harnessed to naturally produce sucrose alternatives that are more beneficial to human health.


Assuntos
Deinococcus , Glucosiltransferases , Glucosiltransferases/química , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Deinococcus/enzimologia , Deinococcus/genética , Concentração de Íons de Hidrogênio , Isomaltose/metabolismo , Isomaltose/química , Isomaltose/análogos & derivados , Sequência de Aminoácidos , Estabilidade Enzimática , Clonagem Molecular , Peso Molecular , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sacarose/metabolismo , Especificidade por Substrato , Cinética , Estrutura Secundária de Proteína , Dissacarídeos
20.
Food Sci Biotechnol ; 33(12): 2815-2823, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39184975

RESUMO

Meju is a traditional Korean soybean brick characterized by diverse microbial communities. The microbial communities in Meju were identified at the phylum and genus levels using high-throughput sequencing. During Meju fermentation, diverse factors such as total bacterial cell numbers, moisture content, salinity, pH, enzyme activities, and free amino acids were monitored. After 30 days of fermentation, microbial adaptation and increased protease activity resulted in significant changes, including an increase in pH and alterations in free amino acid content by day 70. Bacterial community analysis revealed significant changes in Bacillus, Lactococcus, and Enterococcus levels as fermentation progressed. The decrease in pH during fermentation was influenced by lactic acid bacteria, which affected bacterial dynamics. At the end of fermentation, the fungal community was dominated by Monascus, Aspergillus, and Scopulariopsis, which affected the free amino acid levels. These results indicate that pH and moisture content may be significant factors in determining microbial communities.

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