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1.
Int J Food Microbiol ; 320: 108508, 2020 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-31986350

RESUMO

Laphet is a traditional fermented food in Myanmar, made from tea leaves (Camellia sinensis) by fermentation with limited air passage. We performed microbial diversity analyses on 14 Laphet products collected from different locations in Myanmar. Amplicon-based sequencing results revealed Lactobacillus and Acetobacter were abundant bacteria and Candida, Pichia, Cyberlindnera, and Debaryomyces were abundant yeast. Using selective media, eight species of lactic acid bacteria and nine species of yeast were isolated; Lactobacillus plantarum and L. collinoides were dominant bacteria and Pichia manshurica, Candida boidinii, and Cyberlindnera jadinii were major yeasts. PCR-DGGE analysis confirmed that most of the dominant bacterial and yeast species found in culture dependent analysis were present in Laphet samples. Microbial diversity and pH of Laphet were different between samples from tea plantation area and local markets due to possible differences in incubation time periods. When tannase activity was tested, 23 among 29 bacterial isolates and two among 36 yeast isolates showed positive activities. These findings provide new insights into microbial diversity of Laphet and increased our understanding of the core bacterial and yeast species involved in the manufacture of Laphet.


Assuntos
Bactérias/isolamento & purificação , Camellia sinensis/microbiologia , Alimentos e Bebidas Fermentados/microbiologia , Microbiologia de Alimentos , Fungos/isolamento & purificação , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Biodiversidade , Hidrolases de Éster Carboxílico/metabolismo , Fermentação , Fungos/classificação , Fungos/genética , Fungos/metabolismo , Mianmar , Folhas de Planta/microbiologia
2.
Food Sci Biotechnol ; 28(6): 1919-1920, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31807366

RESUMO

[This corrects the article DOI: 10.1007/s10068-016-0091-x.].

3.
Int J Mol Sci ; 20(23)2019 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-31771257

RESUMO

Flavonols, the second most abundant flavonoids in green tea, exist mainly in the form of glycosides. Flavonols are known to have a variety of beneficial health effects; however, limited information is available on their fate in the digestive system. We investigated the digestive stability of flavonol aglycones and glycosides from green tea under simulated digestion and anaerobic human fecal fermentation. Green tea fractions rich in flavonol glycosides and aglycones, termed flavonol-glycoside-rich fraction (FLG) and flavonol-aglycone-rich fraction (FLA) hereafter, were obtained after treatment with cellulase and tannase, respectively. Kaempferol and its glycosides were found to be more stable in simulated gastric and intestinal fluids than the derivatives of quercetin and myricetin. Anaerobic human fecal fermentation with FLG and FLA increased the populations of Lactobacilli spp. and Bifidobacteria spp. and generated various organic acids, such as acetate, butyrate, propionate, and lactate, among which butyrate was produced in the highest amount. Our findings indicate that some stable polyphenols have higher bioaccessibilities in the gastrointestinal tract and that their health-modulating effects result from their interactions with microbes in the gut.


Assuntos
Fezes/microbiologia , Flavonóis/metabolismo , Chá/química , Técnicas de Cultura Celular por Lotes , Bifidobacterium/isolamento & purificação , Hidrolases de Éster Carboxílico/metabolismo , Celulase/metabolismo , Flavonoides/química , Flavonoides/metabolismo , Flavonóis/química , Glicosídeos/química , Glicosídeos/metabolismo , Humanos , Quempferóis/química , Quempferóis/metabolismo , Lactobacillus/isolamento & purificação , Quercetina/química , Quercetina/metabolismo , Chá/metabolismo
4.
J Microbiol Biotechnol ; 29(11): 1729-1738, 2019 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-31635439

RESUMO

In sourdough fermentation, lactic acid bacteria perform important roles in the production of volatile and antimicrobial compounds, and exerting health-promoting effects. In this study, we report the probiotic properties and baking characteristics of Lactobacillus plantarum SPC-SNU 72-2 isolated from kimchi. This strain is safe to use in food fermentation as it does not carry genes for biogenic amine production (i.e., hdc, tdc, and ldc) and shows no ß-hemolytic activity against red blood cells. The strain is also stable under simulated human gastrointestinal conditions, showing tolerance to gastric acid and bile salt, and adheres well to colonic epithelial cells. Additionally, this strain prevents pathogen growth and activates mouse peritoneal macrophages by inducing cytokines such as tumor necrosis factor-α, interleukin (IL)-6, and IL-12. Furthermore, the strain possesses good baking properties, providing rich aroma during dough fermentation and contributing to the enhancement of bread texture. Taken together, L. plantarum SPC-SNU 72-2 has the properties of a good starter strain based on the observation that it improves bread flavor and texture while also providing probiotic effects comparable with commercial strains.


Assuntos
Pão/microbiologia , Alimentos e Bebidas Fermentados/microbiologia , Microbiologia de Alimentos , Lactobacillus plantarum/metabolismo , Probióticos/metabolismo , Animais , Antibiose , Aderência Bacteriana , Ácidos e Sais Biliares/metabolismo , Pão/análise , Células CACO-2 , Fermentação , Humanos , Imunomodulação , Lactobacillus plantarum/genética , Lactobacillus plantarum/fisiologia , Maltose/metabolismo , Camundongos , Viabilidade Microbiana , Probióticos/análise , Compostos Orgânicos Voláteis/análise
5.
J Microbiol Biotechnol ; 29(1): 37-43, 2019 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-30798571

RESUMO

The gene encoding an α-L-arabinofuranosidase (BvAF) GH51 from Bacillus velezensis FZB42 was cloned and expressed in Escherichia coli. The corresponding open reading frame consists of 1,491 nucleotides which encode 496 amino acids with the molecular mass of 56.9 kDa. BvAF showed the highest activity against sugar beet (branched) arabinan in 50 mM sodium acetate buffer (pH 6.0) at 45°C. However, it could hardly hydrolyze debranched arabinan and arabinoxylans. The time-course hydrolyses of branched arabinan and arabinooligosaccharides (AOS) revealed that BvAF is a unique exo-hydrolase producing exclusively L-arabinose. BvAF could cleave α-(1,2)- and/or α-(1,3)-L-arabinofuranosidic linkages of the branched substrates to produce the debranched forms of arabinan and AOS. Although the excessive amount of BvAF could liberate L-arabinose from linear AOS, it was extremely lower than that on branched AOS. In conclusion, BvAF is the arabinan-specific exo-acting α-L-arabinofuranosidase possessing high debranching activity towards α-(1,2)- and/or α-(1,3)-linked branches of arabinan, which can facilitate the successive degradation of arabinan by endo-α-(1,5)-L-arabinanase.


Assuntos
Bacillus/enzimologia , Proteínas de Bactérias/metabolismo , Glicosídeo Hidrolases/metabolismo , Polissacarídeos/metabolismo , Sequência de Aminoácidos , Arabinose/metabolismo , Bacillus/genética , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Beta vulgaris/química , Clonagem Molecular , Escherichia coli/enzimologia , Escherichia coli/genética , Expressão Gênica , Glicosídeo Hidrolases/química , Glicosídeo Hidrolases/genética , Glicosídeo Hidrolases/isolamento & purificação , Concentração de Íons de Hidrogênio , Hidrólise , Cinética , Peso Molecular , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Especificidade por Substrato , Temperatura
6.
Front Microbiol ; 9: 2781, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30524399

RESUMO

The industrial application of microorganisms as starters or probiotics requires their preservation to assure viability and metabolic activity. Freezing is routinely used for this purpose, but the cold damage caused by ice crystal formation may result in severe decrease in microbial activity. In this study, adaptive laboratory evolution (ALE) technique was applied to a lactic acid bacterium to select tolerant strains against freezing and thawing stresses. Lactobacillus rhamnosus GG was subjected to freeze-thaw-growth (FTG) for 150 cycles with four replicates. After 150 cycles, FTG-evolved mutants showed improved fitness (survival rates), faster growth rate, and shortened lag phase than those of the ancestor. Genome sequencing analysis of two evolved mutants showed genetic variants at distant loci in six genes and one intergenic space. Loss-of-function mutations were thought to alter the structure of the microbial cell membrane (one insertion in cls), peptidoglycan (two missense mutations in dacA and murQ), and capsular polysaccharides (one missense mutation in wze), resulting in an increase in cellular fluidity. Consequently, L. rhamnosus GG was successfully evolved into stress-tolerant mutants using FTG-ALE in a concerted mode at distal loci of DNA. This study reports for the first time the functioning of dacA and murQ in freeze-thaw sensitivity of cells and demonstrates that simple treatment of ALE designed appropriately can lead to an intelligent genetic changes at multiple target genes in the host microbial cell.

7.
J Ginseng Res ; 42(4): 412-418, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30337801

RESUMO

Background: Ginsenoside Rg3(S) and compound K (C-K) are pharmacologically active components of ginseng that promote human health and improve quality of life. The aim of this study was to produce Rg3(S) and C-K from ginseng extract using recombinant Lactococcus lactis. Methods: L. lactis subsp. cremoris NZ9000 (L. lactis NZ9000), which harbors ß-glucosidase genes (BglPm and BglBX10) from Paenibacillus mucilaginosus and Flavobacterium johnsoniae, respectively, was reacted with ginseng extract (protopanaxadiol-type ginsenoside mixture). Results: Crude enzyme activity of BglBX10 values comprised 0.001 unit/mL and 0.003 unit/mL in uninduced and induced preparations, respectively. When whole cells of L. lactis harboring pNZBglBX10 were treated with ginseng extract, after permeabilization of cells by xylene, Rb1 and Rd were converted into Rg3(S) with a conversion yield of 61%. C-K was also produced by sequential reactions of the permeabilized cells harboring each pNZBgl and pNZBglBX10, resulting in a 70% maximum conversion yield. Conclusion: This study demonstrates that the lactic acid bacteria having specific ß-glucosidase activity can be used to enhance the health benefits of Panax ginseng in either fermented foods or bioconversion processes.

8.
Food Sci Biotechnol ; 27(1): 73-78, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30263726

RESUMO

Lactic acid bacteria (LAB) are key for the fermentation of sourdoughs to improve the quality and nutritive value of bread. The aim of this study was to isolate the LAB starter for sourdough fermentation from Jeung-pyun, a Korean traditional rice cake. Among the twenty two LAB screened, five isolates were selected based on exo-polysaccharide production. Among them, three isolates showed cell growth greater than 8.5 Log CFU/g, maximum increase in the volume of dough, and dextran concentration up to 0.16%. During the sourdough fermentation, pH and total titratable acidity (TTA) were changed, as the three isolates synthesized lactic acid and acetic acid with fermentation quotients less than 2.0. They were identified as Leuconostoc lactis EFEL005, Lactobacillus brevis EFEL004, and Le. citreum EFEL006. They displayed good fermentation properties (growth, dextran production, pH, and TTA) in dough and they are regarded as potential starters to be used in sourdough fermentation.

9.
J Biotechnol ; 287: 52-58, 2018 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-30142412

RESUMO

Leuconostoc citreum is an important lactic acid bacterium used as a starter culture for producing kimchi, the traditional Korean fermented vegetables. An efficient host strain for plasmid transformation, L. citreum EFEL2700, was isolated from kimchi, and it has been frequently used for genetic engineering of L. citreum. In this study, we report the whole genome sequence of the strain and its genetic characteristics. Genome assembly yielded 5 contigs (1 chromosome and 4 plasmids), and the complete genome contained 1,923,830 base pairs (bp) with a G + C content of 39.0%. Average nucleotide identity analysis showed high homology (≥ 99%) to the reference strain L. citreum KM 20. The smallest plasmid (4.3 kbp) was used as an Escherichia coli shuttle vector (pCB) for heterologous gene expression, and L. citreum EFEL2700 showed the highest transformation efficiency, 6.7 × 104 CFU µg-1 DNA. Genetic analysis of the genome enabled the construction of primary metabolic pathway showing a typical hetero-type lactic acid fermentation. Notably, no core genes for primary metabolism were observed in plasmid 4 and it could be eliminated to create an efficient host for gene transformation. This report will facilitate the understanding and application of L. citreum EFEL2700 as a food-grade microbial cell factory.


Assuntos
Engenharia Genética/métodos , Vetores Genéticos/genética , Genoma Bacteriano/genética , Leuconostoc/genética , Sequência de Bases/genética , DNA Bacteriano/genética , Alimentos e Bebidas Fermentados/microbiologia , Leuconostoc/classificação , Leuconostoc/isolamento & purificação , Análise de Sequência de DNA
10.
J Anim Physiol Anim Nutr (Berl) ; 102(5): 1257-1265, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29968943

RESUMO

Essential oils are widely used in the pharmaceutical, food and cosmetic industries, and many plant essential oils have shown that they have positive effects on broilers nutrition. This experiment was conducted to study the effects of orally administered different dosages of carvacrol essential oils on intestinal barrier function in broiler chickens. A total of eighty 28-day-old (1.28 ± 0.15 kg) ROSS 308 broilers were randomly allocated to four groups of 20 replicates each, with one chicken per replicate per cage, and all were fed with the same diet. Four experimental groups were orally administered 0, 200, 300 or 400 µl carvacrol essential oils at 18:00 hr every day during the 2-week experimental period. As a result of which, the gene expression of the occludin, claudin-1, claudin-5, ZO-1 and ZO-2 in intestinal mucosa of small intestine (p < 0.05) and the goblet cell content in small intestine epithelium (p < 0.05) were significantly increased; test subjects with 300 or 400 µl carvacrol essential oils reduced the microbial counts of Salmonella spp. and Escherichia coli in the intestines (p < 0.05); Essential oils administration also significantly increased activity of the sucrase (p < 0.05) and lactase (p < 0.05) in intestinal mucosa. In conclusion, the carvacrol essential oils have positive effects on growth performance and intestinal barriers function of broilers; those effects may be related to the dosage, as administration of 300 or 400 µl was more effective than that of 200 µl.


Assuntos
Galinhas , Microbioma Gastrointestinal/efeitos dos fármacos , Intestinos/fisiologia , Monoterpenos/farmacologia , Óleos Voláteis/farmacologia , Administração Oral , Ração Animal , Fenômenos Fisiológicos da Nutrição Animal/efeitos dos fármacos , Animais , Galinhas/microbiologia , Galinhas/fisiologia , Cimenos , Dieta , Suplementos Nutricionais , Relação Dose-Resposta a Droga , Microbioma Gastrointestinal/fisiologia , Intestinos/efeitos dos fármacos
11.
J Microbiol Biotechnol ; 28(8): 1293-1298, 2018 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-29996619

RESUMO

Phosphomannomutase (ManB) converts mannose-6-phosphate (M-6-P) to mannose-1-phosphate (M-1-P), which is a key metabolic precursor for the production of GDP-D-mannose used for production of glycoconjugates and post-translational modification of proteins. The aim of this study was to express the manB gene from Escherichia coli in Lactococcus lactis subsp. cremoris NZ9000 and to characterize the encoded enzyme. The manB gene from E. coli K12, of 1,371 bp and encoding 457 amino acids (52 kDa), was cloned and overexpressed in L. lactis NZ9000 using the nisin-controlled expression system. The enzyme was purified by Ni-NTA column chromatography and exhibited a specific activity of 5.34 units/mg, significantly higher than that of other previously reported ManB enzymes. The pH and temperature optima were 8.0 and 50°C, respectively. Interestingly, the ManB used in this study had two substrate specificity for both mannose-1-phosphate and glucose-1-phosphate, and the specific activity for glucose-1-phosphate was 3.76 units/mg showing 70% relative activity to that of mannose-1-phosphate. This is the first study on heterologous expression and characterization of ManB in lactic acid bacteria. The ManB expression system constructed in this study canbe used to synthesize rare sugars or glycoconjugates.


Assuntos
Escherichia coli/genética , Expressão Gênica , Lactococcus lactis/genética , Lactococcus lactis/metabolismo , Fosfotransferases (Fosfomutases)/genética , Fosfotransferases (Fosfomutases)/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/metabolismo , Clonagem Molecular , Glucofosfatos/metabolismo , Concentração de Íons de Hidrogênio , Manosefosfatos/metabolismo , Fosfotransferases (Fosfomutases)/isolamento & purificação , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Especificidade por Substrato , Temperatura
12.
Sci Rep ; 8(1): 8852, 2018 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-29891982

RESUMO

The lactic acid bacteria (LAB) Leuconostoc citreum are non-sporulating hetero-fermentative bacteria that play an important role in the fermented food industry. In this study, for the enhanced and reliable production of recombinant proteins in L. citreum, we developed a bicistronic design (BCD) expression system which includes a short leader peptide (1st cistron) followed by target genes (2nd cistron) under the control of a single promoter. Using superfolder green fluorescent protein (sfGFP) as a reporter, the functionality of BCD in L. citreum was verified. Further, to improve the expression in BCD, we tried to engineer a Shine-Dalgarno sequence (SD2) for the 2nd cistron and a promoter by FACS screening of random libraries, and both strong SD2 (eSD2) and promoter (P710V4) were successfully isolated. The usefulness of the engineered BCD with P710V4 and eSD2 was further validated using three model proteins-glutathione-s-transferase, human growth hormone, and α-amylase. All examined proteins were successfully produced with levels highly increased compared with those in the original BCD as well as the monocistronic design (MCD) expression system.


Assuntos
Leuconostoc/genética , Proteínas Recombinantes/biossíntese , Glutationa Transferase/biossíntese , Glutationa Transferase/genética , Proteínas de Fluorescência Verde/genética , Hormônio do Crescimento Humano/biossíntese , Hormônio do Crescimento Humano/genética , Proteínas Recombinantes/genética , alfa-Amilases/biossíntese , alfa-Amilases/genética
13.
Sci Rep ; 7(1): 15721, 2017 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-29147021

RESUMO

Obligate heterofermentative lactic acid bacteria (LAB) are well-known for their beneficial health effects in humans. To delineate the incompletely characterized metabolism that currently limits their exploitation, at systems-level, we developed a genome-scale metabolic model of the representative obligate heterofermenting LAB, Leuconostoc mesenteroides (iLME620). Constraint-based flux analysis was then used to simulate several qualitative and quantitative phenotypes of L. mesenteroides, thereby evaluating the model validity. With established predictive capabilities, we subsequently employed iLME620 to elucidate unique metabolic characteristics of L. mesenteroides, such as the limited ability to utilize amino acids as energy source, and to substantiate the role of malolactic fermentation (MLF) in the reduction of pH-homeostatic burden on F0F1-ATPase. We also reported new hypothesis on the MLF mechanism that could be explained via a substrate channelling-like phenomenon mainly influenced by intracellular redox state rather than the intermediary reactions. Model simulations further revealed possible proton-symporter dependent activity of the energy efficient glucose-phosphotransferase system in obligate heterofermentative LAB. Moreover, integrated transcriptomic analysis allowed us to hypothesize transcriptional regulatory bias affecting the intracellular redox state. The insights gained here about the low ATP-yielding metabolism of L. mesenteroides, dominantly controlled by the cellular redox state, could potentially aid strain design for probiotic and cell factory applications.


Assuntos
Fermentação , Perfilação da Expressão Gênica , Genoma Bacteriano , Leuconostoc mesenteroides/genética , Leuconostoc mesenteroides/metabolismo , Anaerobiose , Simulação por Computador , Glucose/metabolismo , Leuconostoc mesenteroides/enzimologia , Leuconostoc mesenteroides/crescimento & desenvolvimento , Manitol/metabolismo , Redes e Vias Metabólicas/genética , Ácido Oxaloacético/metabolismo , Oxirredução , Fosfotransferases/metabolismo , Ácido Pirúvico/metabolismo , Reprodutibilidade dos Testes , Simportadores/metabolismo , Termodinâmica , Transcrição Genética
14.
J Biotechnol ; 264: 1-7, 2017 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-29050879

RESUMO

GDP-l-fucose is an l-fucose donor to synthesize fucosylated compounds such as human milk oligosaccharides or Lewis antigen. In this study, we used Lactococcus lactis subsp. cremoris NZ9000 to express 4 enzymes, ManB, ManC, Gmd, and WcaG and produced GDP-l-fucose by using one-pot synthesis method with mannose-6-phosphate as substrate and the enzymes as biocatalyst. For preparation of enzyme mixture, 4 genes (manB, manC, gmd, and wcaG) cloned from Escherichia coli were transformed into L. lactis strains using pNZ8008 and the recombinant cell lysates were obtained after cultivation. When mannose-6-phosphate was used as the substrate, the consecutive reactions with ManB, ManC, Gmd, and WcaG resulted in the successful production of GDP-l-fucose (0.13mM). When GDP-d-mannose was used as the substrate, it was entirely converted to GDP-l-fucose (0.2mM; 0.12g/L) via 2 enzymatic reactions mediated by Gmd and WcaG. This is the first report of GDP-l-fucose production by using multiple enzymes expressed in lactic acid bacteria.


Assuntos
Proteínas de Bactérias/metabolismo , Guanosina Difosfato Fucose/metabolismo , Lactococcus lactis/metabolismo , Manosiltransferases/metabolismo , Engenharia Metabólica/métodos , Proteínas de Bactérias/genética , Escherichia coli/genética , Lactococcus lactis/genética , Manose-6-Fosfato Isomerase/genética , Manose-6-Fosfato Isomerase/metabolismo , Manosiltransferases/genética , Redes e Vias Metabólicas/genética , Oxirredutases/genética , Oxirredutases/metabolismo , Plasmídeos , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
15.
J Microbiol Biotechnol ; 27(12): 2112-2118, 2017 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-29032647

RESUMO

Leuconostoc mesenteroides is used as a starter to produce high-quality kimchi products. In this study, an efficient and economical cabbage juice medium (CJM) was developed by process optimization of cabbage extraction and pasteurization and by compositional supplementation of various lacking nutrients. The pasteurized cabbage juice was determined to be a good medium candidate to cultivate L. mesenteroides, showing maximal cell numbers (9.85 × 108CFU/ml) after 24 h. Addition of sucrose and yeast extract with soy peptone resulted in increment of bacterial cell counts in CJM, showing the supplementing effect of the lacking nutrients. Furthermore, addition of shell powder gave a protective effect on bacterial cells by preventing pH decline and organic acid accumulation in CJM, resulting in a 2-fold increase of bacterial counts. The optimized composition of CJM was 70% cabbage juice diluted with water, 0.5% (w/v) sucrose, 1% (w/v) yeast extract, 1% (w/v) soy peptone, and 1.5% (w/v) ark shell powder. The CJM developed in this study was able to yield a comparable level of bacterial counts with MRS medium and reduced the cost by almost 10-fold.


Assuntos
Brassica/química , Meios de Cultura/química , Microbiologia de Alimentos , Sucos de Frutas e Vegetais/microbiologia , Leuconostoc mesenteroides/crescimento & desenvolvimento , Contagem de Colônia Microbiana , Fermentação , Alimentos e Bebidas Fermentados/microbiologia , Concentração de Íons de Hidrogênio , Proteínas de Soja , Sacarose
16.
J Microbiol Biotechnol ; 27(10): 1736-1743, 2017 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-28813780

RESUMO

Sourdough is made by fermentation of dough by lactic acid bacteria (LAB) and yeast to improve bread properties like volume, flavor, and texture. A Korean traditional sourdough was made by fermenting rice flour with rice wine (makgeolli) and used to make sponge-like bread (jeung-pyun). The aim of this study was to investigate the microbial diversity of makgeolli products and their influence on the organoleptic quality of jeung-pyun. Three commercial makgeolli were tested for jeung-pyun production, with each product exhibiting varied dough swelling rates and organoleptic qualities, and among them, J-product was ranked highest in texture and taste. Microbial analysis of the three makgeolli also showed a big difference in their population and diversity. J-product had the highest LAB and yeast counts, and the predominant species were Lactobacillus casei, Lactobacillus brevis, Leuconostoc pseudomenteroides, and Saccharomyces cerevisiae. Using J-product, sourdough was fermented at 25°C, 30°C, and 35°C, and the microbial growth in and textural properties of jeung-pyun were examined by instrumental and sensory tests. At high temperature (35°C), the rates of dough swelling and acidification were fast due to rapid microbial growth mainly caused by LAB, resulting in a short leavening time and soft and sour jeung-pyun. Sensory tests showed consumer preference for the soft and mild-sour jeung-pyun. This study shows that LAB in makgeolli play key roles in production of jeung-pyun, influencing the textural and sensory properties. For the production of high-quality jeung-pyun, development of LAB starters with high gas productivity and low acidity and establishment of an optimal fermentation procedure for rice dough are necessary.


Assuntos
Bebidas Alcoólicas/microbiologia , Biodiversidade , Microbiologia de Alimentos , Lactobacillales/classificação , Lactobacillales/isolamento & purificação , Oryza/microbiologia , Sensação , Bebidas Alcoólicas/análise , Pão , DNA Bacteriano , Fermentação , Farinha/análise , Farinha/microbiologia , Concentração de Íons de Hidrogênio , Lactobacillales/crescimento & desenvolvimento , Lactobacillales/metabolismo , Filogenia , RNA Ribossômico 16S , Temperatura , Vinho/microbiologia
17.
J Microbiol Biotechnol ; 27(9): 1602-1608, 2017 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-28683524

RESUMO

White rose petal extract (WRE) contains large amounts of phenolic compounds and is considered edible. In this study, red and white wines were prepared by the addition of WRE (0.10% or 0.25% (w/v)), followed by fermentation at 25°C for 15 days. The fermentation profiles, colors, sensory test results, and antioxidant activities of the wines were compared. As reported herein, the fermentation profiles of the pH, CO2 production rate, and final ethanol concentration were not affected by the addition of WRE, but a slow consumption rate of sugar was observed in 0.25% WRE-added wine. In contrast, the total polyphenol concentrations in WRE-added wines increased significantly (p < 0.05) in a dose-dependent manner, resulting in appreciable enhancement of the antioxidant activities of the wines. Chromaticity tests showed slight changes in the redness and yellowness, but sensory tests showed that the overall flavor qualities of the WRE-added wines were acceptable to the panels. This study demonstrates that addition of WRE to wine confers beneficial health effects and this treatment results in better outcome in white wine.


Assuntos
Antioxidantes , Extratos Vegetais , Rosa/química , Vinho/análise , Álcoois , Antioxidantes/química , Antioxidantes/metabolismo , Benzotiazóis/análise , Benzotiazóis/metabolismo , Compostos de Bifenilo/análise , Compostos de Bifenilo/metabolismo , Fermentação , Ácido Gálico , Concentração de Íons de Hidrogênio , Picratos/análise , Picratos/metabolismo , Extratos Vegetais/química , Extratos Vegetais/metabolismo , Polifenóis , Ácidos Sulfônicos/análise , Ácidos Sulfônicos/metabolismo
18.
Int J Syst Evol Microbiol ; 67(7): 2225-2230, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28671527

RESUMO

The type strains of four subspecies of Leuconostocmesenteroides, L. mesenteroidessubsp. mesenteroides, L. mesenteroidessubsp. cremoris, L. mesenteroidessubsp. dextranicum and L. mesenteroidessubsp. suionicum, and strain DRC1506T, used as a starter culture for commercial kimchi production in Korea, were phylogenetically analyzed on the basis of their complete genome sequences. Although the type strains of the four L. mesenteroides subspecies and strain DRC1506T shared very high 16S rRNA gene sequence similarities (>99.72 %), the results of analysis of average nucleotide identity (ANI), in silico DNA-DNA hybridization (DDH) and core-genome-based relatedness indicated that they could form five different phylogenetic lineages. The type strains of L. mesenteroidessubsp. mesenteroides, L. mesenteroidessubsp. cremoris and L. mesenteroidessubsp. dextranicum and DRC1506T shared higher ANI and in silico DDH values than the thresholds (95-96 % and 70 %, respectively) generally accepted for different species delineation, whereas the type strain of L. mesenteroidessubsp. suionicum (DSM 20241T) shared lower ANI (<94.1 %) and in silico DDH values (<57.0 %) with the other four L. mesenteroides lineage strains, indicating that DSM 20241T couldn be reclassified as representing a different species. Here, we report that DRC1506T represents a novel subspecies within the species Leuconostoc mesenteroides, for which the name Leuconostoc mesenteroidessubsp. jonggajibkimchii subsp. nov. is proposed. The type strain is DRC1506T (=KCCM 43249T=JCM 31787T). In addition, L. mesenteroidessubsp. suionicum is also reclassified as Leuconostoc suionicum. sp. nov. (type strain DSM 20241T=ATCC 9135T=LMG 8159T=NCIMB 6992T).


Assuntos
Leuconostoc mesenteroides/classificação , Leuconostoc/classificação , Filogenia , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , República da Coreia , Análise de Sequência de DNA
19.
J Biotechnol ; 251: 151-155, 2017 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-28433723

RESUMO

Leuconostoc spp. are important lactic acid bacteria for the fermentation of foods. In particular, L. citreum strains isolated from various foods have been used as host strains for genetic and metabolic engineering studies. In order to develop a food-grade genetic engineering system, L. citreum CB2567 was isolated from Kimchi. However, the isolated bacterium contained a cryptic plasmid which was difficult to eliminate. As the existence of the plasmid might hinder strain engineering, we eliminated the plasmid using an RNA-guided DNA endonuclease CRISPR/Cas9 system. We demonstrated that a plasmid-free L. citreum CB2567 host strain could be efficiently constructed through a two-step procedure: 1) transformation of the "killer" plasmid expressing Cas9 endonuclease and a guide RNA (gRNA) targeting for a specific sequence in the cryptic plasmid, and 2) serial subculture without antibiotics for curing the killer plasmid. When the crude extract of L. citreum expressing Cas9 and the guide RNA was incubated with a PCR fragment containing the specific sequence recognized by the guide RNA, the PCR fragment was cleaved. Also, the cryptic plasmid pCB42 was successfully eliminated from the host strain after transforming the plasmid harboring Cas9 and the guide RNA. The Cas9 and gRNA expression plasmid used in this study can be applied for genome engineering purposes by additionally introducing an editing DNA template to repair the double strand DNA breakage caused by Cas9 in the genome of L. citreum. This study demonstrates the feasibility of developing CRISPR/Cas9-based genetic engineering tools to develop a safe host strain and construct food-grade lactic acid bacteria without residual antibiotic markers.


Assuntos
Leuconostoc/genética , Plasmídeos , Sistemas CRISPR-Cas , Engenharia Genética
20.
PLoS One ; 12(4): e0176098, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28423055

RESUMO

The ginsenoside Rh2, a pharmaceutically active component of ginseng, is known to have anticancer and antitumor effects. However, white ginseng and red ginseng have extremely low concentrations of Rh2 or Rh2-Mix [20(S)-Rh2, 20(R)-Rh2, Rk2, and Rh3]. To enhance the production of food-grade ginsenoside Rh2, an edible enzymatic bioconversion technique was developed adopting GRAS host strains. A ß-glucosidase (BglPm), which has ginsenoside conversion ability, was expressed in three GRAS host strains (Corynebacterium glutamicum, Saccharomyces cerevisiae and Lactococus lactis) by using a different vector system. Enzyme activity in these three GRAS hosts were 75.4%, 11.5%, and 9.3%, respectively, compared to that in the E. coli pGEX 4T-1 expression system. The highly expressed BglPm_C in C. glutamicum can effectively transform the ginsenoside Rg3-Mix [20(S)-Rg3, 20(R)-Rg3, Rk1, Rg5] to Rh2-Mix [20(S)-Rh2, 20(R)-Rh2, Rk2, Rh3] using a scaled-up biotransformation reaction, which was performed in a 10-L jar fermenter at pH 6.5/7.0 and 37°C for 24 h. To our knowledge, this is the first report in which 50 g of PPD-Mix (Rb1, Rb2, Rb3, Rc, and Rd) as a starting substrate was converted to ginsenoside Rg3-Mix by acid heat treatment and then 24.5-g Rh2-Mix was obtained by enzymatic transformation of Rg3-Mix through by BglPm_C. Utilization of this enzymatic method adopting a GRAS host could be usefully exploited in the preparation of ginsenoside Rh2-Mix in cosmetics, functional food, and pharmaceutical industries, thereby replacing the E. coli expression system.


Assuntos
Proteínas de Bactérias/genética , Proteínas Fúngicas/genética , Ginsenosídeos/metabolismo , Microbiologia Industrial/métodos , beta-Glucosidase/genética , Proteínas de Bactérias/metabolismo , Biotransformação , Clonagem Molecular , Corynebacterium glutamicum/enzimologia , Corynebacterium glutamicum/genética , Escherichia coli/enzimologia , Escherichia coli/genética , Proteínas Fúngicas/metabolismo , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Ginsenosídeos/química , Concentração de Íons de Hidrogênio , Cinética , Lactococcus lactis/enzimologia , Lactococcus lactis/genética , Peso Molecular , Panax/química , Engenharia de Proteínas , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/genética , Temperatura , beta-Glucosidase/metabolismo
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