Lipidomic Profiling of PFOA-Exposed Mouse Liver by Multi-Modal Mass Spectrometry Analysis.

Perfluorooctanoic acid (PFOA) is a synthetic perfluorinated chemical classified as a persistent organic pollutant. PFOA has been linked to many toxic effects, including liver injury. Many studies report that PFOA exposure alters serum and hepatic lipid metabolism. However, lipidomic pathways altered by PFOA exposure are largely unknown and only a few lipid classes, mostly triacylglycerol (TG), are usually considered in lipid analysis. Here, we performed a global lipidomic analysis on the liver of PFOA-exposed (high-dose and short-duration) and control mice by combining three mass spectrometry (MS) techniques: liquid chromatography with tandem mass spectrometry (LC-MS/MS), matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI), and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Among all hepatic lipids identified by LC-MS/MS analysis, more than 350 were statistically impacted (increased or decreased levels) after PFOA exposure, as confirmed by multi-variate data analysis. The levels of many lipid species from different lipid classes, most notably phosphatidylethanolamine (PE), phosphatidylcholine (PC), and TG, were significantly altered. Subsequent lipidomic analysis highlights the pathways significantly impacted by PFOA exposure, with the glycerophospholipid metabolism being the most impacted, and the changes in the lipidome network, which connects all the lipid species together. MALDI-MSI displays the heterogeneous distribution of the affected lipids and PFOA, revealing different areas of lipid expression linked to PFOA localization. TOF-SIMS localizes PFOA at the cellular level, supporting MALDI-MSI results. This multi-modal MS analysis unveils the lipidomic impact of PFOA in the mouse liver after high-dose and short-term exposure and opens new opportunities in toxicology.

The complex puzzle of dietary silver nanoparticles, mucus and microbiota in the gut.

Hundreds of consumer and commercial products containing silver nanoparticles (AgNPs) are currently used in food, personal-care products, pharmaceutical, and many other applications. Human exposure to AgNPs includes oral intake, inhalation, and dermal contact. The aim of this review was to focus on oral intake, intentional and incidental of AgNPs where well-known antimicrobial characteristics that might affect the microbiome and mucus in the gastrointestinal tract (GIT). This critical review summarizes what is known regarding the impacts of AgNPs on gut homeostasis. It is fundamental to understand the forms of AgNPs and their physicochemical characterization before and during digestion. For example, lab-synthesized AgNPs differ from "real" ingestable AgNPs used as food additives and dietary supplements. Similarly, the gut environment alters the chemical and physical state of Ag that is ingested as AgNPs. Emerging research on in vitro and in vivo rodent and human indicated complex multi-directional relationships among AgNPs, the intestinal microbiota, and the epithelial mucus. It may be necessary to go beyond today's descriptive approach to a modeling-based ecosystem approach that might quantitatively integrate spatio-temporal interactions among microbial groups, host factors (e.g., mucus), and environmental factors, including lifestyle-based stressors. It is suggested that future research (1) utilize more representative AgNPs, focus on microbe/mucus interactions, (2) assess the effects of environmental stressors for longer and longitudinal conditions, and (3) be integrated using quantitative modeling.

Impact of mycotoxins on the intestine: are mucus and microbiota new targets?

There is an increasing awareness of the deleterious effects attributed to mycotoxins during their fate within the gut, particularly for deoxynivalenol (DON), zearalenone (ZEN), ochratoxin A (OTA), fumonisin B1 (FB1), aflatoxin B1 (AFB1), and patulin (PAT). Evidence indicates that disruption of the epithelial barrier is well established. However, intestinal barrier function on its luminal side involves two other partners, mucus and microbiota, which have rarely been considered in the context of mycotoxin exposure. The current review aimed at providing a summary of DON, ZEN, OTA, FB1, AFB1, and PAT effects on intestinal barrier function, with special focus on mucus and microbiota. DON, ZEN, OTA, FB1, AFB1, and PAT are known to markedly affect epithelial cell integrity and functions. Regarding mucus, DON is the most documentated mycotoxin. In vivo, toxicological impact of DON generally has only been assessed through goblet cell number. Evaluation of the mycotoxins/mucus interplay considering other indicators such as composition, thickness, and penetrability of mucus, mucin O-glycosylation thus warrants further attention. With respect to microbiota, few short-term studies to date have been reported indicating deleterious effects. However, long-term exposure to mycotoxins may also produce significant changes in microbiota composition and metabolic activity, which requires further experimentation. In conclusion, mucus and microbiota are key targets for dietary mycotoxins although assessment of induced effects is preliminary. A significant research effort is now underway to determine the adverse consequences of mycotoxins on mucus and microbiota considered as individual but also as tightly connected gut players.

Characterization of a novel dextransucrase from Weissella confusa isolated from sourdough.

Weissella confusa and Weissella cibaria isolated from wheat sourdoughs produce, from sucrose, linear dextrans due to a single soluble dextransucrase. In this study, the first complete gene sequence encoding dextransucrase from a W. confusa strain (LBAE C39-2) along with the one from a W. cibaria strain (LBAE K39) were reported. Corresponding gene cloning was achieved using specific primers designed on the basis of the draft genome sequence of these species. Deduced amino acid sequence of W. confusa and W. cibaria dextransucrase revealed common structural features of the glycoside hydrolase family 70. Notably, the regions located in the vicinity of the catalytic triad (D, E, D) are highly conserved. However, comparison analysis also revealed that Weissella dextransucrases form a distinct phylogenetic group within glucansucrases of other lactic acid bacteria. We then cloned the W. confusa C39-2 dextransucrase gene and successfully expressed the mature corresponding enzyme in Escherichia coli. The purified recombinant enzyme rDSRC39-2 catalyzed dextran synthesis from sucrose with a K m of 8.6 mM and a V max of 20 µmol/mg/min. According to (1)H and (13)C NMR analysis, the polymer is a linear class 1 dextran with 97.2 % α-(1→6) linkages and 2.8 % α-(1→3) branch linkages, similar to the one produced by W. confusa C39-2 strain. The enzyme exhibited optimum catalytic activity for temperatures ranging from 35 to 40 °C and a pH of 5.4 in 20 mM sodium acetate buffer. This novel dextransucrase is responsible for production of dextran with predominant α-(1→6) linkages that could find applications as food hydrocolloids.

Genome sequence of Weissella confusa LBAE C39-2, isolated from a wheat sourdough.

Weissella confusa is a rod-shaped heterofermentative lactic acid bacterium from the family of Leuconostocaceae. Here we report the draft genome sequence of the strain W. confusa LBAE C39-2 isolated from a traditional French wheat sourdough.

Genome sequences of three Leuconostoc citreum strains, LBAE C10, LBAE C11, and LBAE E16, isolated from wheat sourdoughs.

Leuconostoc citreum is a key microorganism in fermented foods of plant origin. Here we report the draft genome sequence for three strains of Leuconostoc citreum, LBAE C10, LBAE C11, and LBAE E16, which have been isolated from traditional French wheat sourdoughs.

Repeated exposure of Caco-2 versus Caco-2/HT29-MTX intestinal cell models to (nano)silver in vitro: Comparison of two commercially available colloidal silver products.

Colloidal silver products are sold for a wide range of disinfectant and health applications. This has increased the potential for human exposure to silver nanoparticles (AgNPs) and ions (Ag+), for which oral ingestion is considered to be a major route of exposure. Our objective was to evaluate and compare the toxicity of two commercially available colloidal silver products on two human intestinal epithelial models under realistic exposure conditions. Mesosilver™ and AgC were characterized and a concentration range between 0.1 and 12 µg/mL chosen. Caco-2 cells vs. co-culture of Caco-2 and mucus-secreting HT29-MTX cells (90/10) were used. Repeated exposure was carried out to determine cell viability over 18 days of cell differentiation in 24-well plates. Selected concentrations (0.1, 1, and 3 µg/mL) were tested on cells cultured in E-plates and Transwells with the same repeated exposure regimen, to determine cell impedance, and cell viability and trans-epithelial electrical resistance (TEER), respectively. Silver uptake, intracellular localisation, and translocation were determined by CytoViva™, HIM-SIMS, and ICP-MS. Genotoxicity was determined on acutely-exposed proliferating Caco-2 cells by γH2AX immunofluorescence staining. Repeated exposure of a given concentration of AgC, which is composed solely of ionic silver, generally exerted more toxic effects on Caco-2 cells than Mesosilver™, which contains a mix of AgNPs and ionic silver. Due to its patchy structure, the presence of mucus in the Caco-2/HT29-MTX co-culture only slightly mitigated the deleterious effects on cell viability. Increased genotoxicity was observed for AgC on proliferating Caco-2 cells. Silver uptake, intracellular localisation, and translocation were similar. In conclusion, Mesosilver™ and AgC colloidal silver products show different levels of gut toxicity due to the forms of distinct silver (AgNPs and/or Ag+) contained within. This study highlights the applicability of high-resolution (chemical) imaging to detect and localize silver and provides insights into its uptake mechanisms, intracellular fate and cellular effects.

Exercise Interventions With Trained Home Helpers for Preventing Loss of Autonomy and Falls in Community-Dwelling Older Adults Receiving Home Heath Physical Therapy T4H: A Randomized Controlled Pilot Study.

BACKGROUND AND PURPOSE: Older adults at risk for falls live independently in the community in their own home and have rehabilitation needs. However, little is known about whether home coaching of older adults can decrease falls at home. We sought to determine whether a novel program for preventing falls and a loss of exercise capacity, the T4H program, in which home helpers act as exercise coaches by using an information technology (IT) device, was acceptable and feasible. METHODS: Between February 2015 and October 2015, we performed a cluster randomized controlled trial in which home helpers either assisted older adults 75 years and over, to participate in the T4H program, or provided standard home help over 3 months. We assessed levels of acceptability and satisfaction among the older adults and home helpers with regard to the exercise program and the technologies used. To measure efficacy, the main outcome measures for the older adults were the absence of falls requiring medical or paramedical care, unplanned hospitalizations, walking ability in a Timed Up and Go test (TUG), and self-care ability by the Barthel Index at the 3-month follow-up visit. RESULTS AND DISCUSSION: Overall, 35 older adults were included, aged 89 years and with 68.6% women. Eighty-five percent of the respondents were pleased or very pleased to have participated in the T4H exercise program, 70% were satisfied with the IT devices, and 92% were satisfied with their home helper's level of involvement. Two of the 4 home helper respondents were satisfied or very satisfied with the exercise program, and 2 were moderately satisfied. The proportions of older adult participants with no falls or no unplanned hospitalizations were higher in the T4H group (92.3% and 85.7%, respectively) than in the control group (81.8% and 71.4%, respectively), although these intergroup differences were not statistically significant. The T4H and control groups did not differ significantly with regard to the TUG time (median [IQR]: 27.6 seconds [17.9-58.6] vs 30.7 seconds [19.7-57.2], respectively) or the Barthel Index (median [IQR]: 90 [75-95] and 90 [75-95], respectively). CONCLUSIONS: The novel T4H home help model was feasible and was associated with a high level of participant satisfaction. We observed a trend toward fewer falls and hospitalizations and better quality of life in the older adults.

Mucus: An Underestimated Gut Target for Environmental Pollutants and Food Additives.

Synthetic chemicals (environmental pollutants, food additives) are widely used for many industrial purposes and consumer-related applications, which implies, through manufactured products, diet, and environment, a repeated exposure of the general population with growing concern regarding health disorders. The gastrointestinal tract is the first physical and biological barrier against these compounds, and thus their first target. Mounting evidence indicates that the gut microbiota represents a major player in the toxicity of environmental pollutants and food additives; however, little is known on the toxicological relevance of the mucus/pollutant interplay, even though mucus is increasingly recognized as essential in gut homeostasis. Here, we aimed at describing how environmental pollutants (heavy metals, pesticides, and other persistent organic pollutants) and food additives (emulsifiers, nanomaterials) might interact with mucus and mucus-related microbial species; that is, "mucophilic" bacteria such as mucus degraders. This review highlights that intestinal mucus, either directly or through its crosstalk with the gut microbiota, is a key, yet underestimated gut player that must be considered for better risk assessment and management of environmental pollution.

Complete Genome Sequence of Lactococcus lactis subsp. lactis A12, a Strain Isolated from Wheat Sourdough.

We report here the complete genome sequence of Lactococcus lactis subsp. lactis strain A12, a strain isolated from sourdough. The circular chromosome and the four plasmids reveal genes involved in carbohydrate metabolism that are potentially required for the persistence of this strain in such a complex ecosystem.

Overview of the glucansucrase equipment of Leuconostoc citreum LBAE-E16 and LBAE-C11, two strains isolated from sourdough.

The whole set of putative glucansucrases from Leuconostoc citreum LBAE-E16 and LBAE-C11 was retrieved from the draft genome sequence of these two sourdough strains previously suggested as alternan producers. Four and five putative glycoside hydrolase family 70 (GH70) encoding genes were identified in the genome sequence of strain C11 and E16, respectively. Some putative genes have high sequence identity to known Leuconostoc dextransucrases. Molecular and biochemical data confirmed that L. citreum C11 could be considered as a new alternan-producing strain, unlike strain E16. In the latter, two new putative glucansucrases with unusual structural features were retrieved. In particular, the GSE16-5 gene encodes for a protein of 2063 amino acids with a theoretical molecular mass of 229 kDa that shares 61% identity with the alternansucrase (ASR) of L. citreum NRRL B-1355, due to the presence of seven APY repeats identified in the C-terminal peptide sequence. Cloning and expression of the corresponding coding sequence revealed synthesis of a low molecular weight (10(4) Da) linear dextran polymer with glucosyl residues only linked by α-1,6 linkages. This novel GH70 enzyme may thus be viewed as a natural chimeric enzyme resulting from the addition of the ASR C-terminal region in a dextransucrase.

Potential osmoprotectants for the lactic acid bacteria Pediococcus pentosaceus and Tetragenococcus halophila.

The physiological responses of the lactic acid bacteria Pediococcus pentosaceus and Tetragenococcus halophila (formely known as P. halophila), subjected to osmotic stress in the presence of molecules known to act as osmoprotectants for other bacteria were studied. In a defined medium, glycine betaine, dimethylsulfonioacetate, choline, proline and L-carnitine were able to relieve inhibition of growth at 0.8 M NaCl. The five compounds were shown to efficiently compete with glycine betaine transport, suggesting the existence of common transporter(s) for these molecules. T. halophila, the most tolerant strain, exhibited a larger spectrum of compatible solutes including dimethylsulfonioacetate, dimethylsulfoniopropionate and ectoine. Preliminary data suggest that restoration of growth by ectoine under osmotic constraint seems specific to the genus Tetragenococcus.

Complete Genome Sequence of Leuconostoc citreum Strain NRRL B-742.

Leuconostoc citreum belongs to the group of lactic acid bacteria and plays an important role in fermented foods of plant origin. Here, we report the complete genome of the Leuconostoc citreum strain NRRL B-742, isolated in 1954 for its capacity to produce dextran.

Characterization of glycosyltransferase activity of wild-type Leuconostoc mesenteroides strains from Bulgarian fermented vegetables.

Glycosyltransferase activity of 13 Leuconostoc mesenteroides strains isolated from Bulgarian fermented vegetables was investigated. All the strains displayed a mucoid phenotype on sucrose-containing agar media. Strains were characterized according to carbohydrate fermentation, species-specific multiple PCR using several primers, repetitive element-PCR fingerprinting using (GTG)(5) primers and glycosyltransferase activity. Level of activity and cellular localization (soluble or cell-associated) were variable among strains. Precipitation of exopolysaccharides produced from sucrose by the soluble fractions from these strains allowed recovery of only glucans and further characterization by (1)H and (13)C NMR analysis and enzymatic digestion with dextranase revealed dextran production. However, levans could be detected in presence of raffinose as fructosyl donor. Both fructosyltransferase and glucosyltransferase encoding genes were detected by PCR and both active enzymes were detected after functional characterization by SDS-PAGE electrophoresis and in situ polymer production after incubation with sucrose. This work therefore showed that concomitant production of glucosyltransferase and fructosyltransferase is widespread in L. mesenteroides strains.

Characterization of dextran-producing Weissella strains isolated from sourdoughs and evidence of constitutive dextransucrase expression.

The study of exopolysaccharide production by heterofermentative sourdough lactic acid bacteria has shown that Weissella strains isolated from sourdoughs produce linear dextrans containing α-(1→6) glucose residues with few α-(1→3) linkages from sucrose. In this study, several dextran-producing strains, Weissella cibaria and Weissella confusa, isolated from sourdough, were characterized according to carbohydrate fermentation, repetitive element-PCR fingerprinting using (GTG)(5) primers and glucansucrase activity (soluble or cell-associated). This study reports, for the first time, the characterization of dextransucrase from Weissella strains using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and in situ polymer production (after incubation with sucrose) from enzymatic fractions harvested from both sucrose and glucose culture media. Results demonstrate that dextransucrase activity was mainly soluble and associated with a constitutive 180-kDa protein. In addition, microsequencing of the active dextransucrase from W. cibaria LBAE-K39 allowed the design of specific primers that could detect the presence of glucansucrase encoding genes similar to GTFKg3 of Lactobacillus fermentum Kg3 and to DSRWC of W. cibaria CMU. This study hence indicates that sourdough Weissella strains synthesize original dextransucrase.

Characterization of glucan-producing Leuconostoc strains isolated from sourdough.

Sourdough was previously demonstrated to be a fruitful biotope for isolation of lactic acid bacteria producing exopolysaccharides and more accurately diverse glycan polymers which have interesting applications as texturing agents or prebiotics. Characterization of polymers by (1)H and (13)C NMR spectroscopy analysis demonstrated that these strains could synthesize glucans of high structural variety and containing different amounts of α-(1→2), α-(1→3) and α-(1→6) linkages. In this study, fifteen glucan-producing Leuconostoc mesenteroides and L. citreum strains from sourdoughs were characterized according to carbohydrate fermentation, rep-PCR fingerprinting using (GTG)(5) primers and glycansucrase activity (soluble or cell-associated). Enzyme characterization using SDS-PAGE and in situ polymer production after incubation with sucrose correlated with synthesis of classical or α-(1→2) branched dextrans, alternan and levan. In addition, the presence of genes coding for alternansucrase was detected by PCR and partially characterized by sequence analysis. We thus provide new information on the biodiversity of glucan production by sourdough Leuconostoc strains.

Biodiversity of lactic acid bacteria in French wheat sourdough as determined by molecular characterization using species-specific PCR.

The lactic acid microflora of nine traditional wheat sourdoughs from the Midi-Pyrénées area (South western France) was previously isolated and preliminary characterized using conventional morphological and biochemical analysis. However, such phenotypic methods alone are not always reliable and have a low taxonomic resolution for identification of lactic acid bacteria species. In the present study, a total of 290 LAB isolates were identified by PCR amplification using different sets of specific primers in order to provide a thorough characterization of the lactic flora from these traditional French sourdoughs. Overall, the LAB isolates belonged to 6 genera: Lactobacillus (39%, 8 species), Pediococcus (38%, 1 species), Leuconostoc (17%, 2 species), Weissella (4%, 2 species), Lactococcus (1%, 1 species) and Enterococcus (<1%, 1 species) and 15 different species were detected: L. plantarum, L. curvatus, L. paracasei, L. sanfranciscensis, L. pentosus, L. paraplantarum, L. sakei, L. brevis, P. pentosaceus, L. mesenteroides, L. citreum, W. cibaria, W. confusa, L. lactis and E. hirae. Facultative heterofermentative LAB represent more than 76% of the total isolates, the main species isolated herein correspond to L. plantarum and P. pentosaceus. Obligate heterofermentative lactobacilli (L. sanfranciscencis, L. brevis) represent less than 3% of the total isolates whereas Leuconostoc and Weissella species represent 21% of the total isolates and have been detected in eight of the nine samples. Detection of some LAB species was preferentially observed depending on the isolation culture medium. The number of different species within a sourdough varies from 3 to 7 and original associations of hetero- and homofermentative LAB species have been revealed. Results from this study clearly confirm the diversity encountered in the microbial community of traditional sourdough and highlight the importance of LAB cocci in the sourdough ecosystem, along with lactobacilli.

Biodiversity of exopolysaccharides produced from sucrose by sourdough lactic acid bacteria.

The distribution and diversity of natural exopolysaccharides (EPS) produced from sucrose by thirty heterofermentative lactic acid bacteria strains from French traditional sourdoughs was investigated. The EPS production was found to be related to glucansucrase and fructansucrase extracellular activities. Depending on the strain, soluble and/or cell-associated glycansucrases were secreted. Structural characterization of the polymers by 1H and 13C NMR spectroscopy analysis further demonstrated a high diversity of EPS structures. Notably, we detected strains that synthesize glucans showing amazing variations in the amount of alpha-(1-->2), alpha-(1-->3) and alpha-(1-->6) linkages. The representation of Leuconostoc strains which produce putative alternan polymers and alpha-(1-->2) branched polymers was particularly high. The existence of glucan- and fructansucrase encoding genes was also confirmed by PCR detection. Sourdough was thus demonstrated to be a very attractive biotope for the isolation of lactic acid bacteria producing novel polymers which could find interesting applications such as texturing agent or prebiotics.

Isolation and characterization of ButA, a secondary glycine betaine transport system operating in Tetragenococcus halophila.

Through functional complementation of an Escherichia coli mutant defective in glycine betaine uptake, we identified a single-component glycine betaine transporter from Tetragenococcus halophila, a moderate halophilic lactic acid bacterium. DNA sequence analysis characterized the ButA protein as a member of the betaine choline carnitine transporter (BCCT) family, that includes a variety of previously characterized compatible solute transporters such as OpuD from Bacillus subtilis, EctP and BetP from Corynebacterium glutamicum, and BetL from Listeria monocytogenes. When expressed in the heterologous host E. coli, the permease is specific for glycine betaine and does not transport the other osmoprotectants previously described for T. halophila (i.e. carnitine, choline, dimethylsulfonioacetate, dimethylsulfoniopropionate, and ectoine). In E. coli, statement of ButA is mainly constitutive and maximal uptake activity may result from a weak osmotic induction. This is the first study demonstrating a role for a permease in osmoregulation, and GB uptake, of a lactic acid bacterium.