Limosilactobacillus reuteri BIO7251 administration improves metabolic phenotype in obese mice fed a high fat diet: an inter-organ crosstalk between gut, adipose tissue and nervous system.

Gut microbiota is implicated in the control of host physiology by releasing bioactive actors that could exert a direct or indirect effect on tissue. A dysfunction of the gut microbiota to tissue axis could participate in the development of pathological states such as obesity and diabetes. The aim of this study was to identify the metabolic effect of Limosilactobacillus reuteri (known as Lactobacillus reuteri) BIO7251 (L. reuteri BIO7251) isolated from Corsican clementine orange. Body weight gain, adiposity, glucose tolerance, glucose absorption and food intake were measured in mice fed a high-fat diet in response to a preventive oral administration of L. reuteri BIO7251. This strain of bacteria exerts a beneficial effect on body weight gain by decreasing the subcutaneous adipose tissue mass. The treatment with L. reuteri BIO7251 decreases glucose absorption and food intake in obese/diabetic mice. L. reuteri BIO7251 could be tested as new probiotic strain that could manage body weight during obesity.

Thoracic Kyphosis and Lumbar Lordosis Distribution After Idiopathic Scoliosis Correction Using Posterior Hybrid Versus Screw Instrumentation.

STUDY DESIGN: This was a retrospective observational study. OBJECTIVE: The aim of this study was to evaluate kyphosis and lordosis distribution, inflexion points, and the relationship with proximal junctional kyphosis (PJK) comparing hybrid instrumentation (in situ contouring, derotation) versus screw instrumentation (thoracic cantilever reduction, lumbar in situ contouring, and derotation). SUMMARY OF BACKGROUND DATA: The combination of reduction techniques aims at restoring the levels of lumbar apex and thoracolumbar inflexion point according to Roussouly alignment types. This approach could minimize the PJK risk after adolescent idiopathic scoliosis (AIS) surgery. MATERIALS AND METHODS: The study assessed coronal curve correction, thoracolumbar and spinopelvic sagittal parameters in 86 skeletally mature adolescents and young adults 2.2 years after AIS correction, comparing a hybrid group (HG, n=34) to a screw group (SG, n=52). Segmental kyphosis and lordosis distribution, number of vertebrae included in curves, thoracic and lumbar apex, thoracolumbar inflexion point and Roussouly types were modeled using KEOPS software. RESULTS: Global coronal and sagittal correction were similar in both groups. In the SG, lumbar lordosis (LL) decreased from 61.1 to 53.9 degrees (P<0.0001) and matched with pelvic incidence (r=0.69), whereas LL did not change in the HG. Postoperatively, the thoracolumbar inflexion point migrated cranially, resulting in a longer LL in both groups. Postoperative thoracolumbar inflexion point (P<0.0001) and the lumbar apex (P=0.0274) were more caudal in the SG compared with the HG. The PJK rate was 14.7% in the HG and 7.7% in the SG. In patients with PJK, lumbar apex and thoracolumbar inflexion point shifted cranially and were too high according to the Roussouly type. CONCLUSIONS: Hybrid and screw instrumentation led to similar global AIS correction, but the use of cantilever reduction in the SG allowed setting the thoracolumbar inflexion point and the lumbar apex lower than in the HG. Cranial migration of these points was identified as PJK risk factor. LEVEL OF EVIDENCE: Level III.

Characterization of antifungal compounds produced by lactobacilli in cheese-mimicking matrix: Comparison between active and inactive strains.

Biopreservation of dairy products by acid lactic bacteria appears as a promising alternative to either replace or reduce the use of chemical preservatives. This study aimed at the identification of bacteria preventing fungal spoilers growth in dairy products, and, at the understanding of their antifungal activity. First, antifungal activity of eighteen Lactobacillus strains was tested against five molds and four yeasts leading to selection of L. casei 7006 which had an activity against seven fungal targets. Then, challenge tests against C. lusistaniae 3668 in a cheese-mimicking matrix have been performed demonstrating that this strain was able to reduce strongly this yeast growth after 14 and 21 days storages at 7 °C. Antifungal compounds produced in cheese-mimicking matrix containing L. casei 7006 strain were quantified, then compared to the one prepared with an inactive strain (L. casei 6960) or without Lactobacillus strain. Three compounds were differently produced between cheeses with or without Lactobacillus strain after 21 days at 7 °C: lactic acid, benzoic acid and diacetyl. However, lactic acid concentrations were similar between the three cheeses after 14 days at 7 °C, but an antifungal activity was only associated to L. casei 7006 presence. Benzoic acid concentrations between cheese with L. casei 7006 and negative control L. casei 6960 were also the same. Among the antifungal molecules retrieved from these analyses, diacetyl was the most significantly overproduced in cheese containing L. casei 7006, thus this volatile was associated to the antifungal activity of this strain.

Intracellular osmoprotectant concentrations determine Propionibacterium freudenreichii survival during drying.

Propionibacterium freudenreichii is a beneficial bacterium widely used in food as a probiotic and as a cheese-ripening starter. In these different applications, it is produced, dried, and stored before being used. Both freeze-drying and spray-drying were considered for this purpose. Freeze-drying is a discontinuous process that is energy-consuming but that allows high cell survival. Spray-drying is a continuous process that is more energy-efficient but that can lead to massive bacterial death related to heat, osmotic, and oxidative stresses. We have shown that P. freudenreichii cultivated in hyperconcentrated rich media can be spray-dried with limited bacterial death. However, the general stress tolerance conferred by this hyperosmotic constraint remained a black box. In this study, we modulated P. freudenreichii growth conditions and monitored both osmoprotectant accumulation and stress tolerance acquisition. Changing the ratio between the carbohydrates provided and non-protein nitrogen during growth under osmotic constraint modulated osmoprotectant accumulation. This, in turn, was correlated with P. freudenreichii tolerance towards different stresses, on the one hand, and towards freeze-drying and spray-drying, on the other. Surprisingly, trehalose accumulation correlated with spray-drying survival and glycine betaine accumulation with freeze-drying. This first report showing the ability to modulate the trehalose/GB ratio in osmoprotectants accumulated by a probiotic bacterium opens new perspectives for the optimization of probiotics production.

Data from a proteomic analysis highlight different osmoadaptations in two strain of Propionibacterium freudenreichii.

The article presents a proteomic data set generated by a comparative analysis of the proteomes of Propionibacterium freudenreichii, comparing the CIRM-BIA 129 and CIRM-BIA 1025 strains. The two strains were cultivated until the beginning of the stationary phase in a chemical defined medium (MMO), and in this medium in the presence of NaCl, with or without glycine betaine. Whole-cell proteins were extracted, trypsinolyzed and analyzed by nano LC-MS/MS, prior to identification and classification by function using the X!Tandem pipeline software and the proteomic data from NCBI.nlm.nigh.gov. Quantification of proteins was then carried out in order to detect change in their expression depending on the culture medium. This article is related to the research article entitled "Benefits and drawbacks of osmotic adjustment in Propionibacterium freudenreichii". The comparative proteomic analysis of the two strains reveal strain-dependent and medium-dependent stress proteomes in the probiotic P. freudenreichii.

Propionibacterium freudenreichii CIRM-BIA 129 Osmoadaptation Coupled to Acid-Adaptation Increases Its Viability During Freeze-Drying.

Propionibacterium freudenreichii is a beneficial bacterium with documented effects on the gut microbiota and on inflammation. Its presence within the animal and human intestinal microbiota was correlated with immunomodulatory effects, mediated by both propionibacterial surface components and by secreted metabolites. It is widely implemented, both in the manufacture of fermented dairy products such as Swiss-type cheeses, and in the production of probiotic food complements, under the form of freeze-dried powders. The bottleneck of this drying process consists in the limited survival of bacteria during drying and storage. Protective pre-treatments have been applied to other bacteria and may, in a strain-dependent manner, confer enhanced resistance. However, very little information was yet published on P. freudenreichii adaptation to freeze-drying. In this report, an immunomodulatory strain of this probiotic bacterium was cultured under hyperosmotic constraint in order to trigger osmoadaptation. This adaptation was then combined with acid or thermal pre-treatment. Such combination led to accumulation of key stress proteins, of intracellular compatible solute glycine betaine, to modulation of the propionibacterial membrane composition, and to enhanced survival upon freeze-drying. This work opens new perspectives for efficient production of live and active probiotic propionibacteria.

Taking Advantage of Bacterial Adaptation in Order to Optimize Industrial Production of Dry Propionibacterium freudenreichii.

Propionibacterium freudenreichii is a beneficial bacterium, used both as a probiotic and as a cheese starter. Large-scale production of P. freudenreichii is required to meet growing consumers' demand. Production, drying and storage must be optimized, in order to guarantee high P. freudenreichii viability within powders. Compared to freeze-drying, spray drying constitutes the most productive and efficient, yet the most stressful process, imposing severe oxidative and thermal constraints. The aim of our study was to provide the tools in order to optimize the industrial production of dry P. freudenreichii. Bacterial adaptation is a well-known protective mechanism and may be used to improve bacterial tolerance towards technological stresses. However, the choice of bacterial adaptation type must consider industrial constraints. In this study, we combined (i) modulation of the growth medium composition, (ii) heat-adaptation, and (iii) osmoadaptation, in order to increase P. freudenreichii tolerance towards technological stresses, including thermal and oxidative constraints, using an experimental design. We further investigated optimal growth and adaptation conditions, by monitoring intracellular compatible solutes accumulation. Glucose addition, coupled to heat-adaptation, triggered accumulation of trehalose and of glycine betaine, which further provided high tolerance towards spray drying and storage. This work opens new perspectives for high quality and fast production of live propionibacteria at the industrial scale.

Benefits and drawbacks of osmotic adjustment in Propionibacterium freudenreichii.

Propionibacterium freudenreichii is a beneficial bacterium used as a cheese starter and as a probiotic. Indeed, selected strains of P. freudenreichii combine both technological and health-promoting abilities. Moreover, during large-scale industrial production of dried bacteria and during consumption, P. freudenreichii may undergo different stressful processes. Osmotic adaptation was shown to enhance P. freudenreichii tolerance towards stresses, which are encountered during freeze-drying and during digestion. In this report, we compared the osmoadaptation molecular mechanisms of two P. freudenreichii strains. Both osmotolerance and osmoadaptation were strain-dependent and had different effects on multiple stress tolerance, depending on the presence of osmoprotectants. Availability of glycine betaine (GB) restored the growth of one of the two strains. In this strain, osmotic preadaptation enhanced heat, oxidative and acid stresses tolerance, as well as survival upon freeze-drying. However, addition of GB in the medium had deleterious effects on stress tolerance, while restoring optimal growth under hyperosmotic constraint. In the other strain, neither salt nor GB enhanced stress tolerance, which was constitutively low. Accordingly, whole cell proteomics revealed that mechanisms triggered by salt in the presence and in the absence of GB are different between strains. Osmotic adjustment may thus have deleterious effects on industrial abilities of P. freudenreichii. BIOLOGICAL SIGNIFICANCE: Propionibacteria are found in various niches including fodder, silage, rumen, milk and cheeses. This means adaptation towards different ecological environments with different physicochemical parameters. Propionibacterium freudenreichii, in particular, is furthermore used both as dairy starter and as probiotic and is thus submitted to high scale industrial production. Production and subsequent stabilization still need optimization. Drying processes like freeze-drying are stressful. Osmotic adjustments may modulated tolerance towards drying. However, they are strain-dependent, medium-dependent and may either reduce or increase stress tolerance. A case-by-case study, for each strain-medium thus seems necessary. In this work, we identify key proteins involved in osmoadaptation and give new insights into adaptation mechanisms in P. freudenreichii. This opens new perspectives for the selections of strains and for the choice of the growth medium composition.

Review: Adaptation of Beneficial Propionibacteria, Lactobacilli, and Bifidobacteria Improves Tolerance Toward Technological and Digestive Stresses.

This review deals with beneficial bacteria, with a focus on lactobacilli, propionibacteria, and bifidobacteria. As being recognized as beneficial bacteria, they are consumed as probiotics in various food products. Some may also be used as starters in food fermentation. In either case, these bacteria may be exposed to various environmental stresses during industrial production steps, including drying and storage, and during the digestion process. In accordance with their adaptation to harsh environmental conditions, they possess adaptation mechanisms, which can be induced by pretreatments. Adaptive mechanisms include accumulation of compatible solutes and of energy storage compounds, which can be largely modulated by the culture conditions. They also include the regulation of energy production pathways, as well as the modulation of the cell envelop, i.e., membrane, cell wall, surface layers, and exopolysaccharides. They finally lead to the overexpression of molecular chaperones and of stress-responsive proteases. Triggering these adaptive mechanisms can improve the resistance of beneficial bacteria toward technological and digestive stresses. This opens new perspectives for the improvement of industrial processes efficiency with regard to the survival of beneficial bacteria. However, this bibliographical survey evidenced that adaptive responses are strain-dependent, so that growth and adaptation should be optimized case-by-case.

A Novel Depsipeptide Produced by Paenibacillus alvei 32 Isolated from a Cystic fibrosis Patient.

The important viscosity of the respiratory tract mucus of Cystic fibrosis (CF) patients impairs the mucociliary transport system and allows the growth of numerous micro-organisms. Among them, Pseudomonas aeruginosa and Staphylococcus aureus are known to be responsible for pulmonary infections. We imagined that CF microflora could also harbour micro-organisms naturally equipped to compete with these pathogens. A method was developed to recover these antibiotic-producing strains within 20 CF sputum. Using this approach, we have isolated an unusual Gram-positive bacterium identified as Paenibacillus alvei by Api galleries and 16S rRNA gene sequence analysis. This strain has inhibited the growth of P. aeruginosa, S. aureus and Klebsiella pneumoniae, in co-cultures. A liquid mineral medium named MODT50 was designed and optimised for the production and the recovery of the antimicrobial compounds. The supernatant has inhibited the growth of all Gram-positive strains tested, even Methicillin-resistant S. aureus. One antimicrobial compound with a peptide structure (mainly active against S. aureus, Micrococcus luteus, and Pseudomonas stutzeri) has been purified and characterised by liquid chromatography-mass spectrometry. The new active molecule (m/z 786.6) named depsipeptide L possesses a 15-guanidino-3-hydroxypentadecanoic acid side chain (m/z 298) linked on a cyclic part of four amino acids residues (Ser, two Leu/Ile, Arg). This work reports for the first time the production of such a molecule by a P. alvei strain in a mineral medium. The CF lung microflora might represent a valuable source for the discovery of new antimicrobial-producing strains.

Ecotoxicoproteomics in gills of the sentinel fish species, Cottus gobio, exposed to perfluorooctane sulfonate (PFOS).

The environmental persistence, bioaccumulative tendency and potential toxicity of perfluorooctane sulfonate (PFOS) have generated great concern. This study aimed at evaluating the toxicity of short-term PFOS exposure in gills of the European bullhead Cottus gobio, a candidate sentinel species, by monitoring the response of some enzymes (citrate synthase CS, cytochrome c oxidase CCO, and lactate dehydrogenase LDH), and by undertaking a proteomic analysis using 2D-DIGE. First, a 96-h exposure to 1mg PFOS/L significantly altered the activity of mitochondrial CS and CCO. Second, 2D-DIGE gels were used to compare gills from the control fish group with tissues from fish exposed for 96h to either 0.1 or 1mg PFOS/L. From the 27 protein spots displaying significant changes in abundance following PFOS exposure, a total of 20 different proteins were identified using nano LC-MS/MS and the Peptide and Protein Prophet of Scaffold software. The differentially expressed proteins that were identified are involved in the general stress response, ubiquitin-proteasome system, energy metabolism, and actin cytoskeleton, which provide clues on the cellular pathways and components mainly affected by PFOS. Moreover, our results showed that most proteins were differentially expressed at the low but not at the high PFOS concentration. This work provides insights into the biochemical and molecular events in PFOS-induced toxicity in gill tissue, and suggests that further studies on the identified proteins could provide crucial information to better understand the mechanisms of PFOS toxicity in fish.

Megamonas rupellensis sp. nov., an anaerobe isolated from the caecum of a duck.

We report here the identification, characterization and culture of a Gram-negative to Gram-variable, rod-shaped, non-spore-forming anaerobic bacterium (strain FM1025(T)) isolated from the caecum of a duck. Phylogenetic analysis based on comparative 16S rRNA gene sequencing showed that this strain clustered with species of the family 'Acidaminococcaceae', with 94.9 % similarity to Megamonas hypermegale DSM 1672(T) and less than 91 % similarity with type strains of Pectinatus species. Sequence similarities of at least 98-99 % were observed with numerous sequences deposited in GenBank of uncultured strains from human and chicken caecal contents, but this strain is the first isolate of this taxon to be cultivated and described. On the basis of morphological, physiological and phylogenetic features, this strain should be assigned to a novel species in the genus Megamonas, for which the name Megamonas rupellensis sp. nov. is proposed. The type strain is strain FM1025(T) (=DSM 19944(T) =CIP 109788(T)).