Riboflavin- and Dextran-Producing FS54 B2: Characterization and Testing for Development of Fermented Plant-Based Beverages.

The use of lactic acid bacteria for developing functional foods is increasing for their ability to synthesize beneficial metabolites such as vitamin B (riboflavin, RF) and postbiotic compounds. Here, the spontaneous mutant FS54 B2 was isolated by treatment of the dextran-producing FS54 strain with roseoflavin. FS54 B2 overproduced RF (4.

Functional characterization of the riboflavin-overproducing and dextran-producing Weissella cibaria BAL3C-5 C120T strain for the development of biofortified plant-based beverages.

Riboflavin (vitamin B) is essential for human beings and it has to be provided by healthy nutrition. The use of fermentation with riboflavin-overproducing lactic acid bacteria (LAB) represents an ideal strategy to generate, by in situ biofortification, functional drinks. These beverages can positively contribute to consumer health and address nutritional deficiencies.

Probiotic Characteristics of Lactiplantibacillus plantarum CECT 9435 and Its Survival and Competitive Properties Under Simulated Conditions of the Child Gut Microbiota.

Probiotics are valuable microorganisms effective in reducing malnutrition-related infections in children. In this work, a collection of lactobacilli strains representative of traditional Andean fermented beverages was in vitro screened for their capability to survive the gastrointestinal transit, to adhere to the intestinal epithelium and to compete under simulated conditions of the child gut microbiota. The results allowed the selection of the riboflavin overproducing strain Lactiplantibacillus plantarum CECT 9435 based on its good rate of survival under in vitro gastrointestinal conditions when included in a food matrix representing the fortified food supplement Incaparina.

Leuconostoc mesenteroides and Liquorilactobacillus mali strains, isolated from Algerian food products, are producers of the postbiotic compounds dextran, oligosaccharides and mannitol.

Six lactic acid bacteria (LAB) isolated from Algerian sheep's milk, traditional butter, date palm sap and barley, which produce dextran, mannitol, oligosaccharides and vitamin B have been characterized. They were identified as Leuconostoc mesenteroides (A4X, Z36P, B12 and O9) and Liquorilactobacillus mali (BR201 and FR123). Their exopolysaccharides synthesized from sucrose by dextransucrase (Dsr) were characterized as dextrans with (1,6)-D-glucopyranose units in the main backbone and branched at positions O-4, O-2 and/or O-3, with D-glucopyranose units in the side chain.

Biotechnological Potential and Safety Evaluation of Dextran- and Riboflavin-Producing Strains for Gluten-Free Baking.

Gluten consumption causes several immunological and non-immunological intolerances in susceptible individuals. In this study, the dextran-producing BAL3C-5 and its derivative, the riboflavin-overproducing strain BAL3C-5 C120T, together with a commercial bakery yeast, were used to ferment gluten-free (GF)-doughs obtained from corn and rice flours at two different concentrations and supplemented with either quinoa, buckwheat, or chickpea to obtain laboratory-scale GF bread. The levels of dextran, riboflavin, and total flavins were determined in the fermented and breads.

A methodology for the selection and characterization of riboflavin-overproducing strains after treatment with roseoflavin.

Fermentative processes by lactic acid bacteria can produce metabolites of interest to the health and food industries. Two examples are the production of B-group vitamins, and of prebiotic and immunomodulatory dextran-type exopolysaccharides. In this study, three riboflavin- and dextran-producing strains (BAL3C-5, BAL3C-7 and BAL3C-22) were used to develop a new method for selection and isolation of spontaneous riboflavin-overproducing mutants.

Proteomic and analyses of dextran synthesis influence on AV1n adaptation to temperature change.

is found in vegetables, fruits, and meat and is used by the food industry in the preparation of dairy products, wines, and sugars. We have previously demonstrated that the dextransucrase of (DsrLL) AV1n produces a high-molecular-weight dextran from sucrose, indicating its potential use as a dextran-forming starter culture. We have also shown that this bacterium was able to produce 10-fold higher levels of dextran at 20°C than at 37°C, at the former temperature accompanied by an increase in gene expression.

riboflavin-overproducing and dextran-producing strains useful for the development of functional bread.

This work describes a method for deriving riboflavin overproducing strains of by exposing three strains (BAL3C-5, BAL3C-7, and BAL3C-22) isolated from dough to increasing concentrations of roseoflavin. By this procedure, we selected one mutant overproducing strain from each parental strain (BAL3C-5 B2, BAL3C-7 B2, and BAL3C-22 B2, respectively). Quantification of dextran and riboflavin produced by the parental and mutant strains in a defined medium lacking riboflavin and polysaccharides confirmed that riboflavin was only overproduced by the mutant strains, whereas dextran production was similar in both mutant and parental strains.

Lactic Acid Bacteria Isolated from Fermented Doughs in Spain Produce Dextrans and Riboflavin.

Many lactic acid bacteria (LAB) produce metabolites with applications in the food industry, such as dextran-type exopolysaccharides (EPS) and riboflavin (vitamin B). Here, 72 bacteria were isolated from sourdoughs made by Spanish bread-makers. In the presence of sucrose, colonies of 22 isolates showed a ropy phenotype, and NMR analysis of their EPS supported that 21 of them were dextran producers.

Selection of Riboflavin Overproducing Strains of Lactic Acid Bacteria and Riboflavin Direct Quantification by Fluorescence.

Riboflavin (vitamin B) is a vitamin of the B group involved in essential biological pathways, including redox reactions and the electron transport chain. Some lactic acid bacteria (LAB) can synthesize riboflavin and this capability is strain-dependent. In the last years, a growing interest has focused on the selection of riboflavin-overproducing food-grade LAB for the vitamin biofortification of fermented foods, as well as for the formulation of innovative functional products.

The Ability of Riboflavin-Overproducing Strains to Survive Under Gastrointestinal Conditions.

Riboflavin, vitamin B2, is essential for humans and has to be obtained from the diet. Some lactic acid bacteria (LAB) produce this vitamin, and they can be used for fortification of foods. This could be an alternative to supplementation with chemically synthesized vitamin, to palliate riboflavin deficiencies in specific groups of people.

Real-Time Detection of Riboflavin Production by Strains and Tracking of Their Gastrointestinal Survival and Functionality and Using mCherry Labeling.

Some strains of lactic acid bacteria (LAB) produce riboflavin, a water-soluble vitamin of the B complex, essential for human beings. Here, we have evaluated riboflavin (B2 vitamin) production by five strains isolated from , a traditional maize-based fermented alcoholic beverage from north-western Argentina and their isogenic riboflavin-overproducing derivatives previously selected using roseoflavin. A direct fluorescence spectroscopic detection method to quantify riboflavin production in bacterial culture supernatants has been tested.

Different Modes of Regulation of the Expression of Dextransucrase in AV1n and MN1.

AV1 strain isolated from a Tunisian avocado was characterized as a dextran producer. The promoter P and the gene encoding the DsrLL dextransucrase responsible for the dextran synthesis were transcriptionally fused to the mCherry coding gene generating the pRCR20 plasmid. Upon plasmid transfer, both AV1n and the dextran non-producing CM70 became red due to expression of the mCherry from the P transcriptional fusion.

In Situ β-Glucan Fortification of Cereal-Based Matrices by Pediococcus parvulus 2.6: Technological Aspects and Prebiotic Potential.

Bacterial exopolysaccharides produced by lactic acid bacteria are of increasing interest in the food industry, since they might enhance the technological and functional properties of some edible matrices. In this work, 2.6, which produces an 2-substituted (1,3)-β-d-glucan exopolysaccharide only synthesised by bacteria, was proposed as a starter culture for the production of three cereal-based fermented foods.

Dextran production by Lactobacillus sakei MN1 coincides with reduced autoagglutination, biofilm formation and epithelial cell adhesion.

In this work we have investigated two dextran-producing lactic acid bacteria, Lactobacillus sakei MN1 and Leuconostoc mesenteroides RTF10, isolated from fermented meat products. These bacteria synthesise dextran when sucrose, but not glucose, is present in the growth medium. The influence of dextran on bacterial aggregation, adhesion and biofilm formation was investigated in cultures challenged with sucrose or glucose.

Draft Genome Sequence of Pediococcus parvulus 2.6, a Probiotic β-Glucan Producer Strain.

We report here the draft genome sequence of the probiotic Pediococcus parvulus 2.6, a lactic acid bacterial strain isolated from ropy cider. The bacterium produces a prebiotic and immunomodulatory exopolysaccharide, and this is the first strain of the P.

Zebrafish gut colonization by mCherry-labelled lactic acid bacteria.

A critical feature of probiotic microorganisms is their ability to colonize the intestine of the host. Although the microbial potential to adhere to the human gut lumen has been investigated in in vitro models, there is still much to discover about their in vivo behaviour. Zebrafish is a vertebrate model that is being widely used to investigate various biological processes shared with humans.

Construction and validation of a mCherry protein vector for promoter analysis in Lactobacillus acidophilus.

Lactobacilli are widespread in natural environments and are increasingly being investigated as potential health modulators. In this study, we have adapted the broad-host-range vector pNZ8048 to express the mCherry protein (pRCR) to expand the usage of the mCherry protein for analysis of gene expression in Lactobacillus. This vector is also able to replicate in Streptococcus pneumoniae and Escherichia coli.

A specific immunological method to detect and quantify bacterial 2-substituted (1,3)-β-D-glucan.

Exopolysaccharides synthesized by lactic acid bacteria have prebiotic properties and contribute to the rheology and texture of fermented foods. Here, we have standardized an immunological method for the specific detection of 2-substituted (1,3)-β-D-glucans. The method allows direct detection and quantification of this exopolysaccharide in culture supernatants containing other mono- and poly-saccharides.

A bacteriocin gene cluster able to enhance plasmid maintenance in Lactococcus lactis.

Background: Lactococcus lactis is widely used as a dairy starter and has been extensively studied. Based on the acquired knowledge on its physiology and metabolism, new applications have been envisaged and there is an increasing interest of using L. lactis as a cell factory.

A new tool for cloning and gene expression in Streptococcus pneumoniae.

A new replicon suitable for cloning and gene expression was successfully introduced into Streptococcus pneumoniae. The non-integrative lactococcal vectors pIL253 (higher-copy) and pIL252 (lower-copy), which are based on the promiscuous theta-replicating plasmid pAMβ1, were established in pneumococcus. The stability and the small size of these plasmids, together with the presence of a helpful multi-cloning site make them a useful genetic tool for gene expression in this bacterium.

Fluorescent protein vectors for promoter analysis in lactic acid bacteria and Escherichia coli.

Fluorescent reporter genes are valuable tools for real-time monitoring of gene expression in living cells. In this study we describe the construction of novel promoter-probe vectors containing a synthetic mCherry fluorescent protein gene, codon-optimized for lactic acid bacteria, divergently linked, or not, to a gene encoding the S65T and F64L variant of the green fluorescent protein. The utility of the transcriptional fusion vectors was demonstrated by the cloning of a single or two divergent promoter regions and by the quantitative evaluation of fluorescence during growth of Lactococcus lactis, Enterococcus faecalis, and Escherichia coli.

Role of tyramine synthesis by food-borne Enterococcus durans in adaptation to the gastrointestinal tract environment.

Biogenic amines in food constitute a human health risk. Here we report that tyramine-producing Enterococcus durans strain IPLA655 (from cheese) was able to produce tyramine under conditions simulating transit through the gastrointestinal tract. Activation of the tyramine biosynthetic pathway contributed to binding and immunomodulation of enterocytes.

Evidence that the essential response regulator YycF in Streptococcus pneumoniae modulates expression of fatty acid biosynthesis genes and alters membrane composition.

The YycFG two-component system, originally identified in Bacillus subtilis, is highly conserved among gram-positive bacteria with low G+C contents. In Streptococcus pneumoniae, the YycF response regulator has been reported to be essential for cell growth, but the signal to which it responds and the gene members of the regulon remain unclear. In order to investigate the role of YycFG in S.