6 research outputs found
Study of survival and functionality of probiotic biofilms formulations using edible polysaccharide gel
Lâobjectif de cette thĂšse est dâencapsuler dans une matrice polyosidique des probiotiques sous forme de biofilm en utilisant comme modĂšle Lactobacillus paracasei ATCC334. La matrice dâencapsulation (billes) est obtenue par gĂ©lification ionique dâune pectine amidĂ©e et faiblement mĂ©thylĂ©e en prĂ©sence dâions calcium. Nous avons remarquĂ© que le rĂ©seau de pectine dans ces billes dâun diamĂštre dâenviron 500 ”m permet la formation de microcolonies sphĂ©riques (biofilm-like) avec une taille de 25 ”m de diamĂštre. Une augmentation de la concentration bactĂ©rienne de L. paracasei ATCC334 de 3 Log dâUFC aprĂšs 24 h de croissance des bactĂ©ries immobilisĂ©es est observĂ©e pour atteindre au sein de ces billes une concentration supĂ©rieure Ă 10 Log dâUFC/g humide. Nous avons Ă©galement notĂ© une distribution homogĂšne des microcolonies dans les billes et une organisation structurĂ©e des bactĂ©ries au sein des microcolonies. En effet, une adhĂ©sion des bactĂ©ries Ă la matrice pectine est observĂ©e ainsi que la prĂ©sence de substances polymĂ©riques permettant de lier les bactĂ©ries les unes aux autres. Les rĂ©sultats suggĂšrent donc des phĂ©nomĂšnes dâinteraction entre le rĂ©seau formĂ© par la pectine et les bactĂ©ries dans les billes. Nous avons montrĂ© que L. paracasei ATCC334 formulĂ©e en biofilm dans ces billes de pectine prĂ©sente une rĂ©sistance accrue Ă un stress gastrique (pH 2) et au sĂ©chage par lyophilisation. La capacitĂ© dâadhĂ©sion des bactĂ©ries formulĂ©es Ă des cellules Ă©pithĂ©liales est conservĂ©e et la pectine semble stimuler cette adhĂ©sion aux cellules de lâhĂŽte. Des rĂ©sultats in-vivo utilisant un modĂšle murin dâinflammation intestinale montrent que les biofilms de L. paracasei ATCC334 sont libĂ©rĂ©s au niveau intestinal oĂč ils sâimplantent notamment dans le cĂŽlon. Des microcolonies de tailles approchant les 20 ”m sont retrouvĂ©es au niveau du cĂŽlon suggĂ©rant que les billes de pectine ont libĂ©rĂ© les bactĂ©ries sous forme de biofilm. Par ailleurs, lâadministration aux souris de la formulation Ă base de pectine avec des biofilms de probiotiques a entrainĂ© chez les souris ayant reçu un traitement DSS (une molĂ©cule capable de dĂ©clencher une inflammation intestinale) : une perte de poids moindre, un Ă©tat de santĂ© gĂ©nĂ©ral amĂ©liorĂ©, une muqueuse colique moins altĂ©rĂ©e ainsi quâune diminution de la rĂ©ponse inflammatoire.The aim of this thesis is to encapsulate biofilm probiotics in a polysaccharide matrix using Lactobacillus paracasei ATCC334 as a model. The encapsulation matrix (beads) is obtained by the ionotropic gelation of amidated low-methoxylated pectin with calcium ions. We noticed that the pectin network in these beads with a diameter of approximately 500 microns, allow the formation of spherical microcolonies (biofilm-like) with a diameter of 25 microns. An increase of 3 Log CFU in the bacterial concentration of L. paracasei ATCC334 is observed after 24 hours of growth of the immobilized bacteria, while the observed concentration in these beads reaches more than 10 Log of CFU/g wet. We also noticed that the microcolonies within the beads are homogeneously distributed and the bacteria within the microcolonies are well structured. Moreover, a bacterial adhesion to the pectin matrix is observed as well as the presence of polymeric substances that bind the bacteria to each other. Our results suggest that interaction phenomenon may take place between pectin network and bacteria within beads. We also showed that biofilms of L. paracasei ATCC334 formulated in these pectin beads exhibit increased resistance to the gastric stress (pH 2) and to the freeze-drying process. In addition, the adhesion capacity of the formulated bacteria to epithelial cells is conserved and pectin seems to stimulate this adhesion to host cells. In-vivo results using a murine model presenting intestinal inflammation showed that L. paracasei ATCC334 biofilms are released in the intestinal level and are specifically implanted in the colon. Moreover, microcolonies of sizes approaching 20 ÎŒm are found in the colon suggesting that the bacteria are released in their biofilm form. In addition, the administration of pectinate beads containing probiotic biofilms to mice which have received a DSS treatment (inducing intestinal inflammation) resulted in: less weight loss of mice, improved their overall health status, less injured colonic mucosa and a decrease in the inflammatory response
Exopolysaccharide produced by Weissella confusa: Chemical characterisation, rheology and bioactivity
International audienceThe purpose of this study was to characterise the production of exopolysaccharide (EPS) by indigenous lactic acid bacteria (LAB) isolated from traditional Algerian dairy products and to evaluate their possible use in agri-foods. Among the collection of isolated strains, the strain Weissella confusa (W4) was selected for its ability to produce EPS once exposed to a sucrose culture medium. EPS produced were first isolated with a standardised method and further characterised in terms of molecular size, antioxidant activity, and rheological properties. Its direct implication in the texture and syneresis of acid milk gel was evaluated offering interesting industrial applications for its use during processes dealing with dairy products
Resveratrol Favors Adhesion and Biofilm Formation of Lacticaseibacillus paracasei subsp. paracasei Strain ATCC334
Bacterial strains of the Lactobacillaceae family are widely used as probiotics for their multifaceted potential beneficial properties. However, no official recommendations for their clinical use exist since, in many cases, oral administrations of these bacteria displayed limited beneficial effects in human. Additional research is thus needed to improve the efficiency of existing strains with strong potential. In this context, we assess in vitro the effects of nine polyphenols to stimulate biofilm formation by lactobacilli, a feature enhancing their functionalities. Among these polyphenols, we identify trans-Resveratrol (referred to hereafter as Resveratrol) as a potent inducer of biofilm formation by Lacticaseibacillus paracasei (formerly designated as Lactobacillus paracasei) ATCC334 strain. This effect is strain-dependent and relies on the enhancement of L. paracasei adhesion to abiotic and biotic surfaces, including intestinal epithelial cells. Mechanistically, Resveratrol modify physico-chemical properties of the bacterial surface and thereby enhances L. paracasei aggregation, subsequently facilitating adhesion and biofilm development. Together, our in vitro data demonstrate that Resveratrol might be used to modulate the behavior of Lactobacilli with probiotic properties. Combination of probiotics and polyphenols could be considered to enhance the probiotic functionalities in further in vivo studies
Intestinal release of biofilm-like microcolonies encased in calcium-pectinate beads increases probiotic properties of Lacticaseibacillus paracasei
International audienceIn this study, we show that calcium pectinate beads (CPB) allow the formation of 20 ”m spherical microcolonies of the probiotic bacteria Lacticaseibacillus paracasei (formerly designated as Lactobacillus paracasei) ATCC334 with a high cell density, reaching more than 10 log (CFU/g). The bacteria within these microcolonies are well structured and adhere to a three-dimensional network made of calcium-pectinate through the synthesis of extracellular polymeric substances (EPS) and thus display a biofilm-like phenotype, an attractive property for their use as probiotics. During bacterial development in the CPB, a coalescence phenomenon arises between neighboring microcolonies accompanied by their peripheral spatialization within the bead. Moreover, the cells of L. paracasei ATCC334 encased in these pectinate beads exhibit increased resistance to acidic stress (pH 1.5), osmotic stress (4.5 M NaCl), the freeze-drying process and combined stresses, simulating the harsh conditions encountered in the gastrointestinal (GI) tract. In vivo, the oral administration of CPB-formulated L. paracasei ATCC334 in mice demonstrated that biofilm-like microcolonies are successfully released from the CPB matrix in the colonic environment. In addition, these CPB-formulated probiotic bacteria display the ability to reduce the severity of a DSS-induced colitis mouse model, with a decrease in colonic mucosal injuries, less inflammation, and reduced weight loss compared to DSS control mice. To conclude, this work paves the way for a new form of probiotic administration in the form of biofilm-like microcolonies with enhanced functionalities