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1.
Food Microbiol ; 89: 103410, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32138982

RESUMO

This study explores the ability of lactic acid bacteria (LAB) to ferment soy juice. The ability of 276 LAB strains from 25 species to ferment the principal soy carbohydrates, sucrose, raffinose or stachyose was tested in synthetic media and a soy juice. Fermented soy juices (FSJs) were characterized for their odor. Selected FSJs were characterized by targeted metabolomics. All Streptococcus, 83% of Leuconostoc and Lactobacillus and 41% of Lactococcus strains were sucrose-positive, while only 36% of all the LAB strains tested were raffinose-positive and 6% stachyose-positive. Nearly all (97%) the sucrose-positive strains fermented soy juice, indicating that an ability to use sucrose is a good criterion to select strains for soy juice fermentation. Among the most efficient acidifying strains, 46 FSJs had an odor deemed to be acceptable. FSJ composition was dependent on both species and strains: 17/46 strains deglycosylated soy juice isoflavones, the 27 S. thermophilus strains converted a mean 4.4 ± 0.1 g/L of sucrose into 3.0 ± 0.1 g/L of lactic acid versus 5.2 ± 0.1 g/L into 2.2 ± 0.1 g/L for the 18 Lactobacillus and one Lactococcus strains. This study highlights the diversity of the metabolic profiles of LAB strains in soy juice fermentation.


Assuntos
Fermentação , Alimentos e Bebidas Fermentados/microbiologia , Sucos de Frutas e Vegetais/microbiologia , Lactobacillales/metabolismo , Odorantes/análise , Manipulação de Alimentos , Microbiologia de Alimentos , Lactobacillus/metabolismo , Lactococcus/metabolismo , Leuconostoc/metabolismo , Soja
2.
Int J Food Microbiol ; 317: 108463, 2020 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-31809966

RESUMO

Paocai is a widely consumed Chinese traditional fermented vegetable product. To understand the effect of temperature on paocai fermentation flora, the bacterial community structure of paocai fermented at 10 °C, 15 °C, 25 °C and 35 °C was analyzed by culture-dependent and culture-independent methods. The results showed that increasing the fermentation temperature in a certain range is beneficial for rapid paocai acid production and shortening of the maturity period. Illumina Miseq sequencing was performed on 56 samples at different fermentation process temperatures using a culture-independent method. A total of 1,964,231 high-quality reads of 16S rRNA V3-V4 regions were obtained, and they were divided into 405 operational taxonomic units (OTUs) and identified as 213 bacterial genera. The bacterial diversity decreased with the progression of fermentation, and some spoiled samples had an increased diversity. The culture-independent method found that at 10 °C, Lactococcus appeared at the start of fermentation, Leuconostoc and Weissella appeared in the middle of fermentation, and Lactobacillus and Leuconostoc dominated fermentation in the late stage. At 15 °C, Lactococcus started fermentation, Leuconostoc appeared in the middle stage, and Lactobacillus was dominant in the late stage. At 25 °C, Lactococcus started fermentation, Weissella and Lactobacillus appeared in the middle stage, and Lactobacillus dominated fermentation in the late stage. Finally, at 35 °C, Lactococcus, Weissella, and Lactobacillus started fermentation, Weissella and Lactobacillus appeared in the middle stage, and Lactobacillus dominated fermentation in the late stage. A total of 647 strains of bacteria were isolated by culture-dependent methods and were divided into 12 genera and 19 species by randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) and 16S ribosomal RNA gene (rDNA) sequencing technology. More types of bacteria were isolated in the early stage of fermentation. At 10 °C, Lactococcus lactis began fermentation, and Lactobacillus brevis and Leuconostoc mesenteroides dominated acid production in the middle and late stages of paocai fermentation. At 15 °C, L. lactis initiates fermentation, while Lactobacillus plantarum dominates the acid fermentation of paocai. At 25 °C and 35 °C, there were a large number of Enterobacteriaceae bacteria in the start-up fermentation stage, and L. plantarum was dominant after 1-2 days of fermentation. Redundancy analysis (RDA) found that the lower the temperature, the more bacterial species that are produced, and the higher the temperature and the longer the time, the more obvious are the effects of L. plantarum on paocai. The results of dominant bacteria studied by culture-dependent and culture-independent methods are similar. The results indicate that most of the dominant microorganisms in the paocai fermentation system are culturable. This discovery can provide data and physical support for modernization and regulation of different types of paocai production.


Assuntos
Fermentação/fisiologia , Alimentos e Bebidas Fermentados/microbiologia , Lactobacillus plantarum/metabolismo , Lactococcus/metabolismo , Leuconostoc/metabolismo , Weissella/metabolismo , Temperatura Baixa , Técnicas de Cultura , DNA Bacteriano/genética , DNA Ribossômico/genética , Microbiologia de Alimentos/métodos , Temperatura Alta , Lactobacillus plantarum/genética , Lactococcus/genética , Leuconostoc/genética , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/genética , Técnica de Amplificação ao Acaso de DNA Polimórfico , Weissella/genética
3.
Microbiol Immunol ; 64(2): 133-142, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31625616

RESUMO

Dysregulation of immune responses to environmental antigens by the intestine leads to the chronic inflammatory disease, inflammatory bowel disease (IBD). Recent studies have thus sought to identify a dietary component that can inhibit lipopolysaccharide (LPS)-induced nuclear factor-kappa beta (NF-κB) signaling to ameliorate IBD. This study assessed if the lactic acid bacteria (LAB) from kimchi, suppresses the expression of tumor necrosis factor-alpha (TNF-α) in peritoneal macrophages induced by LPS. Leuconostoc lactis EJ-1, an isolate from LAB, reduced the expression of interleukin-6 (IL-6) and IL-1ß in peritoneal macrophages induced by LPS. The study further tested whether EJ-1 alleviates colitis induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS) in mice. TNBS significantly increased myeloperoxidase (MPO) expression, macroscopic colitis scores, and colon shortening. Oral administration of L. lactis EJ-1 resulted in an inhibited in TNBS-induced loss in body weight, colon shortening, MPO activity, and NF-κB and inducible nitric oxide synthase expression; it also led to a marked reduction in cyclooxygenase-2 expression. L. lactis EJ-1 also inhibited the TNBS-induced expression of TNF-α, IL-1ß, and IL-6; however, it induced the expression of IL-10. The M2 macrophage markers arginase I, IL-10, and CD206 were elevated by EJ-1. Collectively, these results suggest that EJ-1 inhibits the NF-κB signaling and polarizes M1- to M2-macrophage transition, which help in ameliorating colitis.


Assuntos
Colite/terapia , Leuconostoc , Lipopolissacarídeos/imunologia , Macrófagos Peritoneais/metabolismo , Plantas Comestíveis/microbiologia , Animais , Colite/induzido quimicamente , Colo/metabolismo , Modelos Animais de Doenças , Doenças Inflamatórias Intestinais/imunologia , Doenças Inflamatórias Intestinais/terapia , Interleucina-10/metabolismo , Interleucina-1beta/metabolismo , Interleucina-6/metabolismo , Leuconostoc/imunologia , Leuconostoc/metabolismo , Lipopolissacarídeos/metabolismo , Camundongos , NF-kappa B/metabolismo , Transdução de Sinais/imunologia , Ácido Trinitrobenzenossulfônico/efeitos adversos
4.
Food Microbiol ; 86: 103349, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31703858

RESUMO

Pistachio powder was added to flour or semolina to evaluate its contribution to increase the amount of lysine in bread. Bread production was carried out by sourdough technology using a selected 3-species (Lactobacillus sanfranciscensis/Leuconostoc citreum/Weissella cibaria) lactic acid bacterial (LAB) starter culture. All sourdoughs were subjected to a long-time fermentation (21 h) and showed levels of LAB around 109 CFU/g, indicating the suitability of pistachio powder for lactic fermentation. Yeasts were also detected, in particular in semolina trials. MiSeq Illumina technology was applied to investigate the bacterial composition of sourdoughs evidencing a different distribution of LAB species among the trials with Lactobacillus as major LAB group in almost all sourdoughs. Physicochemical parameters were comparable among the trials. After baking, pistachio powder was found not to influence the height of the breads, but pistachio breads were more firm than control breads. Color of the breads, void fraction and cell density, were influenced by pistachio powder. The amount of lysine increased consistently thanks to pistachio supplementation which also determined a higher presence of o-xylene, p-cymene and limonene and the appearance of α-pinene and 1-octen-3-ol in breads. Sensory tests showed the best appreciation scores for the breads produced with flour and pistachio powder.


Assuntos
Pão/análise , Aditivos Alimentares/análise , Lactobacillus/metabolismo , Leuconostoc/metabolismo , Lisina/análise , Pistacia/química , Weissella/metabolismo , Pão/microbiologia , Fermentação , Farinha/análise , Aditivos Alimentares/metabolismo , Alimentos Fortificados/análise , Alimentos Fortificados/microbiologia , Humanos , Lisina/metabolismo , Paladar
5.
Molecules ; 24(21)2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31694180

RESUMO

Glycosyltransferase-producing Leuconostoc lactis CCK940 produces CCK- oligosaccharides, gluco-oligosaccharide molecules, using sucrose and maltose as donor and acceptor molecules, respectively. In this study, the immunostimulatory activities of CCK-oligosaccharides on RAW264.7 macrophages and BALB/c mice were evaluated. CCK-oligosaccharides induced the expression of phosphorylated-p38, extracellular-signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) and upregulation of phagocytic activity in RAW264.7 macrophages, suggesting their involvement in mitogen-activated protein kinase (MAPK) signaling pathway and phagocytosis. When CCK-oligosaccharides were administered to mice intraperitoneally injected with cyclophosphamide (CY), spleen indices and expressions of interleukin (IL)-6, IL-10, and tumor necrosis factor-α increased, compared with those in only CY-treated group. These findings suggest that CCK-oligosaccharides can be used as an effective immunostimulating agent.


Assuntos
Leuconostoc/metabolismo , Oligossacarídeos/farmacologia , Animais , Linhagem Celular , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Imunização/métodos , Interleucina-10/metabolismo , Interleucina-6/metabolismo , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Fagocitose/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Células RAW 264.7 , Transdução de Sinais/efeitos dos fármacos , Fator de Necrose Tumoral alfa/metabolismo , Regulação para Cima/efeitos dos fármacos , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo
6.
Molecules ; 24(21)2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31694205

RESUMO

Leuconostoc lactis CCK940, which exhibits glycosyltransferase activity, produces oligosaccharides using sucrose and maltose as donor and receptor molecules, respectively. The oligosaccharides produced were purified by Bio-gel P2 chromatography and the purified oligosaccharides (CCK-oligosaccharides) consisted of only glucose. 1H-NMR analysis revealed that the CCK-oligosaccharides were composed of 77.6% α-1,6 and 22.4% α-1,4 glycosidic linkages, and the molecular weight of the CCK-oligosaccharides was found to be 9.42 × 102 Da. To determine the prebiotic effect of the CCK-oligosaccharides, various carbon sources were added in modified media. Growth of six probiotic strains, Lactobacillus casei, L. pentosus, L. plantarum, Weissella cibaria, Bifidobacterim animalis, and Saccharomyces cerevisiae, was better when the CCK-oligosaccharides were used as the sole carbon source compared to fructo-oligosaccharides, which are widely used as prebiotics. These results showed that the CCK-oligosaccharides produced from Leu. lactis CCK940 could serve as good candidates for novel prebiotics.


Assuntos
Leuconostoc/metabolismo , Oligossacarídeos/química , Bifidobacterium/metabolismo , Fermentação/fisiologia , Lactobacillus/metabolismo , Maltose/química , Prebióticos , Probióticos/química , Sacarose/química
7.
Food Funct ; 10(8): 4985-4997, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31347616

RESUMO

Sugar reduction in sweet baked goods is one of the most popular trends on the food market. However, reducing sugar without lowering the product quality with respect to sweetness, texture and microbial shelf life is challenging. Sugar alcohols are one group of sugar replacers which maintain the bulk and contribute to sweetness. Nevertheless, alternative approaches, particularly those that are seen as 'clean label', are highly demanded. Hence, the natural, in situ production of mannitol in a sourdough system was performed and its potential as a functional ingredient to improve the product quality of a sugar-reduced cake was investigated. A full sugar cake (C1), a 50% sugar-reduced cake with wheat starch (C2) or with commercially available mannitol (C3) were considered as controls. The substitution of sugar by wheat starch or mannitol caused lower specific volume (-15.5%; -10.7%), a harder crumb (+17.1 N; +4.4 N), less browning, a shorter microbial shelf life (-5.7 days; -4.3 days) and poorer sensory properties. The incorporation of sourdough in C2 improved the pasting properties by decreasing the peak viscosity. Moreover, it resulted in a similar specific volume to the full-sugar control, contributed to significantly softer crumb (-8.6 N) and increased browning compared to C2. Sensory evaluation revealed an increased sweetness perception (+93%), aroma (+30%) and flavour (+25.5%) by the incorporation of sourdough. Although sourdough incorporation improved sugar-reduced cakes, the quality characteristics of the full-sugar control could not be achieved in this study. In conclusion, the addition of sourdough in amounts lower than 10% can be considered a useful tool to improve specific volume, crumb structure, colour, taste and flavour, as well as shelf life of sugar-reduced cakes.


Assuntos
Pão/análise , Açúcares/análise , Paladar , Adulto , Pão/microbiologia , Feminino , Fermentação , Manipulação de Alimentos , Humanos , Leuconostoc/metabolismo , Masculino , Manitol/análise , Controle de Qualidade , Amido/química , Triticum/química , Triticum/microbiologia , Viscosidade , Adulto Jovem
8.
J Food Sci ; 84(8): 2289-2296, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31334849

RESUMO

The sensory characteristics of goat yogurt could be greatly improved by integrating to a culture typical of yogurt starters, Streptococcus thermophilus, Lactobacillus delbrueckii spp. bulgaricus, with cultures of Leuconostoc lactis. The addition of L. lactis requires the use of the definition of  "fermented milk" to the product, although it is prepared according to the same technology. The experimental plan has designed the use of inoculation with a bacterial concentration of at least 109 , for each microbial species considered, with the aim of increasing the probiotic effect of yogurt and fermented milk. Descriptive analysis of the samples was conducted using the profile sheet obtained applying the consensus profiling method (UNI EN ISO 13299:2010) by a trained panel. The acceptability of our products was evaluated by 62 consumers through 7-points hedonic scale. The results of this study indicated that the addition of L. lactis to the traditional yogurt starter produced a noticeable improvement to the sensory characteristics of fermented goat milk. PRACTICAL APPLICATION: To improve the sensory characteristics of goat's yogurt to make it more acceptable to the consumer and increase market demand we tested the integration of Leuconostoc lactis to typical starter cultures. The experimentation carried out tested different combinations of fermenting microorganisms with the aim of developing a better flavor as compared to that of traditional yogurt, which is often unpleasant to consumers. The addition of L. lactis to the starter culture of the goat's milk results in less aggressive aromatic notes and greater appreciation as confirmed by consumers who tested the product.


Assuntos
Microbiologia de Alimentos/métodos , Paladar , Iogurte/análise , Animais , Feminino , Fermentação , Cabras , Humanos , Lactobacillus delbrueckii/metabolismo , Leuconostoc/metabolismo , Masculino , Leite/química , Leite/microbiologia , Probióticos/metabolismo , Streptococcus thermophilus/metabolismo , Iogurte/microbiologia
9.
World J Microbiol Biotechnol ; 35(7): 102, 2019 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-31236715

RESUMO

Preparation of curd vary worldwide due to which its taste, texture and impact on human health also differ. In Assam, curd prepared from raw milk (RMC) is preferred over curd prepared from boiled milk (BMC), a tradition believed to have originated from the Mongoloid customs. Microbial diversity of raw milk (RM), boiled milk (BM), RMC and BMC collected from three farms were investigated by culture dependent and independent techniques. Additionally, metabolite profiles of RMC and BMC were studied by gas chromatography and mass spectroscopy. A total of 59 bacterial isolates were identified from the four different dairy products. In RM, lactic acid bacteria such as Lactococcus, Enterococcus, Lactobacillus and Leuconostoc were obtained along with the environmental bacteria like Bacillus, Staphylococcus, Acetobacter, Chryseobacterium, Streptococcus, Acinetobacter, Kocuria, Klebsiella and Macrococcus. Additionally, Prevotella, Oscillospira, Phascolarctobacterium and Akkermansia were also detected in BM by culture independent technique. In RMC and BMC, Lactococcus, Leuconostoc and Lactobacillus were prevalent. RM and RMC shared Enterococcus, Lactococcus, Streptococcus and Acinetobacter as common bacterial genera. However, no bacterial genus was common in BM and BMC. The correlation analysis revealed that Lactobacillus was negatively correlated to other bacterial genera. Oligotyping analysis revealed that Lactobacillus brevis and L.fermentum were abundant in RMC and BMC, respectively. In metabolomic study, ascorbic acid, dodecanoic acid and hexadecanoic acid were found to be significantly higher in RMC. Presence of different types of probiotics in these curds samples opens a new avenue to understand their effects on human health.


Assuntos
Bactérias/isolamento & purificação , Biodiversidade , Fermentação , Leite/microbiologia , Animais , Bactérias/metabolismo , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , Enterococcus/isolamento & purificação , Enterococcus/metabolismo , Manipulação de Alimentos , Microbiologia de Alimentos , Sequenciamento de Nucleotídeos em Larga Escala , Lactobacillales , Lactobacillus/isolamento & purificação , Lactobacillus/metabolismo , Lactococcus/isolamento & purificação , Lactococcus/metabolismo , Leuconostoc/isolamento & purificação , Leuconostoc/metabolismo , Metagenômica , Análise Multivariada , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/isolamento & purificação
10.
Int J Food Microbiol ; 302: 80-89, 2019 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-31208534

RESUMO

A marketing study revealed that commercially available burger buns can contain up to 10% (w/w) of added sugar. In order to reduce sugar and maintaining the product quality at the same time, functional ingredients and alternative sweetening agents have to be incorporated. In this study, the sourdough lactic acid bacteria Leuconostoc citreum TR116, selected for its ability to produce high amounts of mannitol, was used to produce wheat sourdough and its biochemical characteristics (cell count, pH, TTA, sugar- and acid profile, as well as mannitol production) were monitored over 48 h. The so produced sourdough was then incorporated, as a functional ingredient, into a sugar reduced burger bun system and the quality characteristics of the dough and the final product were determined. Sourdough incorporation counteract the negative effects of sugar reduction on dough properties and resulted in the same viscoelastic properties (0.423 ±â€¯0.008) and gluten-network-development (PMT: 160 ±â€¯12.6 s; TM: 44.0 ±â€¯2.6 BU) as the full-sugar control dough. Furthermore, the investigation of specific volume, crumb hardness and chewiness revealed no significant differences between sugar reduced sourdough burger buns and its control. It is noteworthy that sourdough contributed to browning reaction resulting in darker crumb and crust colour (-8.2%; -9.6%) and it extended microbial shelf life of the burger buns significantly (+3.5 days). Sensory evaluation showed no significant differences in sweetness and sourness between sugar reduced buns containing sourdough and the full-sugar control. In conclusion, the incorporation of mannitol-rich sourdough fermented by Leuconostoc citreum TR116 represents a novel technological approach in the field of sugar reduction and showed high potential as a functional ingredient to ameliorate the losses of important quality parameters. Especially sourdough containing higher amounts of mannitol and lower amounts of lactate improved significantly the dough and burger bun quality.


Assuntos
Pão/análise , Leuconostoc/metabolismo , Manitol/metabolismo , Açúcares/análise , Triticum/microbiologia , Pão/microbiologia , Fermentação , Glutens/análise , Glutens/metabolismo , Ácido Láctico/análise , Ácido Láctico/metabolismo , Açúcares/metabolismo , Triticum/química
11.
Carbohydr Polym ; 220: 103-109, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31196527

RESUMO

Alternansucrase (ALT, EC 2.4.1.140) catalyses the formation of an alternating 〈-1, 3/1, 6-linked glucan, with periodic branch points, from sucrose substrate. Beyond the catalytic domain, this enzyme harbours seven additional C-terminal SH3-like repeats. We herein generated two truncated alternansucrases, possessing deletions of three and seven adjacent SH3 motifs, giving Δ3SHALT and Δ7SHALT. Δ3SHALT and Δ7SHALT exhibited kcat/Km for transglycosylation activity 2.3- and 1.5-fold lower than wild-type ALT (WTALT), while hydrolysis was detected only in the truncated ALTs, oligosaccharide patterns and polymer glycosidic linkage were similar to that of WTALT. The viscosities of ALT polymers increase by ˜100-fold at 15% (w/v), with gel-like states formed at 12.5, 15.0, and 20.0% (w/v) produced by polymer from WTALT, Δ3SHALT, and Δ7SHALT, respectively. The average nanoparticle sizes of Δ3SHALT and Δ7SHALT polymers were 80 nm, compared to 90 nm from WTALT. In conclusion, even relatively subtle differences in the structure of ALT-produced alternan give rise to profound impact on the glucan polymer physicochemical properties.


Assuntos
Glucanos , Glicosiltransferases , Leuconostoc/metabolismo , Domínios de Homologia de src/genética , Glucanos/química , Glucanos/metabolismo , Glicosiltransferases/química , Glicosiltransferases/genética , Hidrólise , Tamanho da Partícula , Deleção de Sequência , Viscosidade
12.
J Agric Food Chem ; 67(24): 6856-6866, 2019 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-31124355

RESUMO

The water kefir organism Leuconostoc citreum TMW 2.1194 forms highly branched dextrans with O3- and O4-bound side chains. To obtain detailed information on the enzymatic synthesis of these polymers, the four glucansucrases encoded by Leuconostoc citreum TMW 2.1194 were cloned, heterologously expressed, and used for polysaccharide production. Molecular and macromolecular structure of the synthesized glucans were analyzed by methylation analysis, two-dimensional NMR spectroscopy, oligosaccharide analysis after partial hydrolysis, and asymmetric flow field-flow fractionation. It was demonstrated that two glucansucrases form insoluble glucans with variously branched dextran sections and varying portions of consecutive, 1,3-linked glucose units. In contrast, the other two glucansucrases synthesized O3- (Lc6255) and O4-branched (Lc1785) soluble dextrans. Analysis, isolation, and characterization of enzymatically liberated oligosaccharides showed that monomeric and elongated side chains are abundant in both polysaccharides. From the structures and size distributions it was concluded that Lc1785 is mainly responsible for synthesis of fermentatively produced soluble dextrans.


Assuntos
Proteínas de Bactérias/metabolismo , Dextranos/química , Dextranos/metabolismo , Leuconostoc/enzimologia , Sacarase/metabolismo , Configuração de Carboidratos , Glucanos/química , Glucanos/metabolismo , Leuconostoc/química , Leuconostoc/metabolismo
13.
Colloids Surf B Biointerfaces ; 181: 25-30, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31121378

RESUMO

This work aims to encapsulate nisin by complexation with exopolysaccharides (EPS), produced by Bacillus tequilensis-GM and Leuconostoc citreum-BMS, namely EPS-GM and EPS-BMS, respectively, using spray-drying technique, and to evaluate the effect of this encapsulation on the structure of nisin. Results related to suspensions turbidity showed that EPS/nisin complexes were formed through electrostatic attractions. These interactions were confirmed by Fourier transform infrared (FTIR) analysis. Scanning electron microscopy (SEM) micrographs of the spray-dried complexes revealed the presence of well-separated spherical microcapsules. Besides, results obtained by UV spectra showed that no significant changes occurred on EPS-GM/nisin microcapsules suggesting that this EPS may act as protective agent of nisin structure against spray-drying conditions.


Assuntos
Bacillus/química , Dessecação , Leuconostoc/química , Nisina/química , Polissacarídeos/química , Substâncias Protetoras/química , Bacillus/metabolismo , Leuconostoc/metabolismo , Tamanho da Partícula , Polissacarídeos/biossíntese , Substâncias Protetoras/metabolismo , Eletricidade Estática , Propriedades de Superfície
14.
J Microbiol ; 57(6): 479-484, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31073899

RESUMO

To develop a starter culture system for improving the shelf-life and quality of kimchi, we prepared a mixed starter composed of Lactococcus lactis and Leuconostoc citreum. Two strains, L. lactis WiKim0098 and Leu. citreum WiKim0096, showed high antimicrobial activity and mannitol productivity, respectively. These lactic acid bacteria (LAB) were introduced as a starter into kimchi following cultivation in foodgrade liquid medium. Two kimchi samples, with and without starter, were fermented for 12 days at 10°C. Compared to the control kimchi without starter, a lower initial pH and higher number of LAB were observed in kimchi with starter at 0 day. However, the starter in kimchi prolonged the period taken by kimchi to reach to pH 4.2 by approximately 1.5-fold compared to that in the control kimchi. To estimate the effect of the starter on the flavor of kimchi, metabolite changes were evaluated by gas chromatography/mass spectrometry. In starter fermented kimchi, the levels of mannitol and amino acid, which are associated with the flavor of kimchi, were increased following fermentation. The amount of mannitol was confirmed by high-performance liquid chromatography analysis, showing concentrations of 3.4 and 5.1 mg/ml for the control and starter fermented kimchi, respectively. Thus, mixed starter inoculated with L. lactis WiKim0098 and Leu. citreum WiKim0096 may extend the shelf-life of kimchi and improve its sensory characteristics.


Assuntos
Alimentos e Bebidas Fermentados/microbiologia , Microbiologia de Alimentos , Armazenamento de Alimentos/métodos , Lactococcus lactis/crescimento & desenvolvimento , Leuconostoc/crescimento & desenvolvimento , Aminoácidos/metabolismo , Fermentação , Concentração de Íons de Hidrogênio , Lactobacillales/crescimento & desenvolvimento , Lactococcus lactis/metabolismo , Leuconostoc/metabolismo , Manitol/metabolismo , Viabilidade Microbiana
15.
Braz J Microbiol ; 50(2): 507-514, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30806891

RESUMO

The use of lactic bacteria in the development of functional foods has increased in recent years. In addition to their probiotic characteristics, they can ferment a variety of substrates, such as cereals, roots, and tubers. Phytase producer lactic acid bacteria strains and their behavior during the fermentation process of yam-based food were studied. Leuconostoc lactis CCMA 0415, Lactobacillus plantarum CCMA 0744, and Lactobacillus fermentum CCMA 0745 were selected due to phytase production, pH reduction, and growth during 24 h of fermentation. Oxalate activity was not detected in all assays, suggesting its concentration was reduced due to the bleaching process. Among the selected strains, L. lactis CCMA 0415 appeared to be a promising strain in yam-based fermentations because it maintained a cell viability above 8 log CFU/mL and did not reduce diosgenin concentrations (around 8.0 µg/mL) after fermentation for 24 h, thereby, generating a potentially functional yam food. Furthermore, this strain promoted the decrease of pH value from 6.1 to 3.8 and produced 8.1 g/L lactic acid, at 6 h of fermentation. The L. lactis CCMA 0415 was reported as a starter culture in fermented products based on cereals, roots, and tubers.


Assuntos
Dioscorea/metabolismo , Fermentação/fisiologia , Alimentos e Bebidas Fermentados/microbiologia , Lactobacillus fermentum/metabolismo , Lactobacillus plantarum/metabolismo , Leuconostoc/metabolismo , 6-Fitase/biossíntese , Alantoína/análise , Dioscorea/microbiologia , Diosgenina/análise , Ácido Láctico/análise , Ácido Oxálico/análise , Compostos Orgânicos Voláteis/análise
16.
Lett Appl Microbiol ; 68(5): 430-436, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30663071

RESUMO

Leuconostoc citreum EFEL2700 isolated from kimchi was used as a host strain for genetic and metabolic engineering in our previous studies, but the cells of EFEL2700 contained a cryptic plasmid (P-cells). Thus, we created plasmid-free cells (F-cells) using the CRISPR/Cas9 system. In this study, we compared the microbial characteristics of P- and F-cells in terms of growth rate, biochemical properties, transformation efficiency, plasmid copy number and protein expression level. When the growth rate was measured in MRS medium at 30°C, no significant difference (P > 0·01) was observed. Biochemical properties, tested using an API 50CHL kit, showed no differences. Transformation efficiency of F-cells, measured using pCB4270, was higher (1·3 × 104 CFU per µg DNA) than that of P-cells (5·0 × 103 CFU per µg DNA). Copy number after transformation of pCBBgl was 4-fold higher for F-cells than for P-cells. When ß-glucosidase activity was assayed in the above experiment, F-cells showed 3·4-fold higher values than P-cells. In conclusion, this study demonstrates that plasmid curing in L. citreum EFEL2700 improves its characteristics as a gene expression host. SIGNIFICANCE AND IMPACT OF THE STUDY: Leuconostoc citreum EFEL2700 (P-cell) isolated from kimchi is a useful food-grade host for expressing heterologous genes. The presence of a cryptic plasmid is thought to limit efficient gene expression. In this study, we compared the microbial and genetic changes after plasmid curing in this strain. The plasmid-free strain showed improved levels of transformation efficiency, copy number and heterologous gene expression without alterations in phenotypes such as the growth rates and biochemical properties. The resulting strain of L. citreum EFEL2701 (F-cell) can be used as an efficient host for genetic engineering.


Assuntos
Regulação Bacteriana da Expressão Gênica/genética , Leuconostoc/genética , Leuconostoc/metabolismo , Plasmídeos/genética , Sistemas CRISPR-Cas/genética , Expressão Gênica/genética , Engenharia Metabólica , beta-Glucosidase/metabolismo
17.
Food Res Int ; 115: 191-199, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30599931

RESUMO

The aim of this study was to investigate the impact of in situ produced exopolysaccharides (EPS) on the rheological and textural properties of fava bean protein concentrate (FPC). EPS (dextrans) were produced from sucrose by two lactic acid bacteria (LAB). The acidification, rheology, and texture of FPC pastes fermented with Leuconostoc pseudomesenteroides DSM 20193 and Weissella confusa VTT E-143403 (E3403) were compared. A clear improvement in rheological and textural parameters was observed in sucrose-added pastes after fermentation, especially with W. confusa VTT E3403. Only moderate proteolysis of fava bean protein during fermentation was observed. The microstructure of the protein in FPC pastes, as observed by confocal laser scanning microscopy, revealed a less continuous and denser structure in EPS-abundant pastes. The beneficial structure formed during EPS-producing fermentation could not be mimicked by simply mixing FPC, isolated dextran, lactic acid, and acetic acid with water. These results emphasize the benefits of in situ produced EPS in connection with the LAB fermentation of legume protein-rich foods. Fermentation with EPS-producing LAB is a cost-effective and clean-labeled technology to obtain tailored textures, and it can further enhance the usability of legumes in novel foods.


Assuntos
Fermentação , Polissacarídeos/metabolismo , Reologia , Vicia faba/metabolismo , Ácido Acético/metabolismo , Dextranos/metabolismo , Fabaceae/metabolismo , Concentração de Íons de Hidrogênio , Ácido Láctico , Lactobacillales/metabolismo , Leuconostoc/metabolismo , Manitol/metabolismo , Sacarose/metabolismo , Weissella/metabolismo
18.
Lett Appl Microbiol ; 67(6): 570-578, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30218539

RESUMO

High molar mass exopolysaccharides (EPS) produced from sucrose by lactic acid bacteria (LAB) are of great interest as natural additives to use in foods, medical and pharmaceutical industry. This study aimed to identify the EPS produced by Leuconostoc citreum L3C1E7 isolated from Pico cheese and characterize the strain for technological and probiotic potential. Purified EPS was isolated from the culture of L. citreum L3C1E7 by ethanol precipitation, with a yield of 520 mg ml-1 . The EPS-producing strain had a mucoid phenotype and average molecular weight of 5·88 × 106  Da. The structural characterization of the purified EPS was determined by 1 H, 13 C and two-dimensional NMR spectroscopy. EPS was composed of alternating α-(1→6)-linked and α-(1→3)-linked D-glucopyranyl units, suggesting the existence of an alternan. The strain was slow acidifying, produced diacetyl and displayed high esterase/lipase and aminopeptidase activities, which promote the desirable flavours in dairy products. Moreover, L. citreum showed moderate resistance to the adverse conditions of the gastrointestinal (GI) tract and high adhesion to GI cells. This work provides a better understanding of EPS produced by L. citreum and the potential application of EPS-producing strain in food and/or as a probiotic culture. SIGNIFICANCE AND IMPACT OF THE STUDY: Some LAB strains are known to use extracellular glycoside-hydrolase enzymes for synthesizing a diversity of exopolysaccharides (EPS) with potential application as natural additives to foods. Previous studies have identified an EPS-producing Leuconostoc citreum strain with immunomodulatory properties. This work provides a better understanding of EPS produced by this strain and the potential application of the strain in food fermentation and/or as a probiotic culture.


Assuntos
Queijo/microbiologia , Leuconostoc/metabolismo , Polissacarídeos Bacterianos/biossíntese , Polissacarídeos Bacterianos/química , Aderência Bacteriana/fisiologia , Células CACO-2 , Linhagem Celular , Fermentação , Trato Gastrointestinal/microbiologia , Células HT29 , Humanos , Leuconostoc/genética , Leuconostoc/isolamento & purificação , Espectroscopia de Ressonância Magnética , Peso Molecular , Plasmídeos/genética , Probióticos
19.
Food Microbiol ; 76: 164-172, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30166137

RESUMO

This study focused on the performance of the dextran producer Leuconostoc citreum as starter culture during 30 days of wheat flour type I sourdough propagation (back-slopping). As confirmed by RAPD-PCR analysis, the strain dominated throughout the propagation procedure, consisting of daily fermentations at 20 °C. The sourdoughs were characterized by consistent lactic acid bacteria cell density and acidification parameters, reaching pH values of 4.0 and mild titratable acidity. Carbohydrates consumption remained consistent during the propagation procedure, leading to formation of mannitol and almost equimolar amount of lactic and acetic acid. The addition of sucrose enabled the formation of dextran, inducing an increase in viscosity of the sourdough of 2-2.6 fold, as well as oligosaccharides. The transcriptional analysis based on glucosyltransferases genes (GH70) showed the existence in L. citreum FDR241 of at least five different dextransucrases. Among these, only one gene, previously identified as forming only α-(1-6) glycosidic bonds, was significantly upregulated in sourdough fermentation conditions, and the main responsible of dextran formation. A successful application of a starter culture during long sourdough back-slopping procedure will depend on the strain robustness and fermentation conditions. Transcriptional regulation of EPS-synthetizing genes might contribute to increase the efficiency of industrial processes.


Assuntos
Farinha/microbiologia , Leuconostoc/genética , Leuconostoc/metabolismo , Polissacarídeos Bacterianos/biossíntese , Polissacarídeos Bacterianos/genética , Transcrição Genética , Triticum/microbiologia , Fermentação , Microbiologia de Alimentos , Perfilação da Expressão Gênica , Glucosiltransferases/genética , Glicosiltransferases , Leuconostoc/efeitos dos fármacos , Leuconostoc/enzimologia , Reação em Cadeia da Polimerase/métodos , Sacarose/farmacologia
20.
Food Microbiol ; 76: 473-480, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30166176

RESUMO

The effect of iodine present in 1.0% table salt in combination with the use of starter cultures in sauerkraut fermentations were investigated in order to determine whether iodine interferes with lactic acid bacteria responsible for the fermentation. The effect of iodine was tested in fermentations performed using selected starter cultures or without starters (spontaneous fermentation). Lactobacillus plantarum and Leuconostoc mesenteroides used as starters at levels of ca. 1 × 107 cfu ml-1 led to a quick establishment of lactic acid bacteria (LAB) as predominant microorganisms, reaching 1 × 109 cfu ml-1 after 24 h decreasing the pH to below 4.0. In contrast, LAB counts in control fermentations without starters increased slower from 1 × 105 cfu ml-1 to 1 × 109 cfu ml-1 and a pH reduction below 4.0 was achieved only after 3 days fermentation. A metagenomic investigation showed a more diverse bacterial community in fermentations without starters, consisting of enterobacteria and pseudomonads in the first days of fermentation, and of LAB such as lactococci in the later stages. In fermentations with starters, lactobacilli predominated. Leuconostocs also occurred, but at much lower sequence abundance than lactobacilli, and thus were not able to predominate. Determination of iodine in the fermentation with starter bacteria and with iodized salt showed that the fermentation did not affect iodine concentration. The use of iodized salt did not statistically significantly influence microbial populations in the fermentation. Thus, there is no basis for the popular held belief that the use of iodized salt inhibits the growth of the bacteria important for the sauerkraut fermentation. A statistically near significant effect (p = 0.06), however, was noted for the effect of iodine on yeasts and mould populations in the fermentations performed without starter cultures. As sauerkraut is usually produced without starters, this should be further investigated.


Assuntos
Bactérias/isolamento & purificação , Bactérias/metabolismo , Biodiversidade , Brassica/microbiologia , Alimentos e Bebidas Fermentados/microbiologia , Iodo/metabolismo , Cloreto de Sódio na Dieta/metabolismo , Bactérias/classificação , Bactérias/genética , Brassica/química , Fermentação , Alimentos e Bebidas Fermentados/análise , Microbiologia de Alimentos , Concentração de Íons de Hidrogênio , Lactobacillus plantarum/genética , Lactobacillus plantarum/isolamento & purificação , Lactobacillus plantarum/metabolismo , Leuconostoc/genética , Leuconostoc/isolamento & purificação , Leuconostoc/metabolismo
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