Quorum sensing effect of chiral d-glutamine on the modulation of the intestinal microbiota of mice by Lactiplantibacillus plantarum A3.

BACKGROUND: Amino acids (AAs) are the building blocks of proteins, but they also serve as biological compounds in biochemical processes, and d-AA isomers are increasingly being recognized as important signaling molecules. As the main organic substrate used by cells in the intestinal tract, the role of the chiral specificity of glutamine is still largely ignored. RESULTS: In a previous study, we found that d-glutamine affected the quorum sensing of Lactiplantibacillus plantarum A3, promoted the release of signaling molecule AI-2 and up-regulated the expression of the LuxS gene. The results showed that when d-glutamine and L. plantarum A3 were simultaneously applied to a mouse model, the diversity and abundance of intestinal flora in both male and female mice were increased. Interestingly, the simultaneous effect of d-glutamine and L. plantarum A3 on the bacterial diversity and abundance of male mice was significantly higher than that of female mice. In addition, the combination of d-glutamine and L. plantarum A3 can improve the host microecology by enhancing the population of Firmicutes such as Lactobacillus and Lachnospiraceae, reducing the population of Fusobacterium and Bacteroides and affecting metabolic pathways such as AA metabolism and transporter transport. CONCLUSION: d-Glutamine, as a signaling molecule, can better stimulate the endogenous d-glutamine synthesis in mice and be utilized by L. plantarum A3. Furthermore, sex differences in the changes of intestinal microflora are also found in this research. This research sheds some light on the adoption of d-AAs combined with lactic acid bacteria in intestinal tract health treatment. © 2024 Society of Chemical Industry.

Enhancement of gum Arabic/casein microencapsulation on the survival of Lactiplantibacillus plantarum in the stimulated gastrointestinal conditions.

Probiotic products that contain lactobacilli have long histories of safe use as Lactobacillus strains have many physiological functions in the gastrointestinal tract (GIT). However, the viability of probiotics can be affected by food processing and the adverse environment. This study investigated the O/W (Oil-in-water emulsions) emulsions formed by coagulation of casein/GA (Gum Arabic) complexes for Lactiplantibacillus plantarum microencapsulation, and the stability of the strains during gastrointestinal environment were also determined. The results showed that the particle size of the emulsion decreased from 9.72 µm to 5.48 µm when the GA concentration increased from 0 to 2 (w/v), and the emulsion particles were found to be more uniform as observed by CLSM (Confocal Laser Scanning Microscope). The surface of this microencapsulated casein/GA composite forms smooth, dense agglomerates and has high viscoelasticity, which effectively improved casein's emulsifying activity (8.66 ± 0.17 m2/g). After the casein/GA complexes microencapsulation, a higher viable count was detected after gastrointestinal digestion in vitro, and the activity of L. plantarum is more stable (about 7.51 log CFU/mL) during 35 days of storage at 4 °C. The results of study will help to design lactic acid bacteria encapsulation systems based on the GIT environment for the oral delivery strategy.

Anti-inflammation and gut microbiota regulation properties of fatty acids derived from fermented milk in mice with dextran sulfate sodium-induced colitis.

The by-products of milk fermentation by lactic acid bacteria provide potential health benefits to the balance of host intestinal microflora. In this study, the anti-inflammatory properties of fatty acids from monoculture-strain (Lactiplantibacillusplantarum A3) and multiple-strain (Streptococcus thermophilus, Lactobacillus bulgaricus, and L. plantarum A3 1:1:2) fermented milk were evaluated in a mouse model of dextran sulfate sodium-induced colitis, and the gut microbiota regulation properties of the fatty acids were also investigated. Results showed that fatty acids can attenuate the inflammatory response by inhibiting the expression of inflammatory factors IL-6 and tumor necrosis factor-α, and blocking the phosphorylation of the JNK in MAPK signal pathway. In addition, the relative abundance of the taxa Akkermansia and Lactobacillus were both enriched after the fatty acid intervention. This finding suggests that fatty acids from the milk fermentation with mixed lactic acid bacteria starters can reduce the severity of dextran sulfate sodium-induced colitis and enhance the abundance of the probiotics in the mice intestinal tract.

Effect of acid and alkali stress on extracellular metabolite profile of Lactobacillus plantarum ATCC 14917.

As a multifunctional lactic acid bacterium, Lactobacillus plantarum has been proved to survive in the human gastrointestinal tract, and it can also colonize this tract. In this study, the effects of L. plantarum ATCC 14917 metabolic profile caused by initial acid-base (pH 5.5 and 8.5) stress were investigated using 1 H nuclear magnetic resonance spectroscopy and multivariate data analysis. The results showed that the metabolome mainly consisted of 14 metabolites, including the components like amino acids, sugars, organic acids, and alkaloids. According to the nontargeted principal component analysis, there was a decrease in most of the metabolites in the alkali-treated group (mainly change in PC1) except acetate, whereas the production of lactate and glycine was increased in the acid-treated group (mainly change in PC2). Furthermore, the initial alkali stress inhibits the secretion of lactic acid, as a decrease was observed in the activity of lactate dehydrogenase and acetic dehydrogenase of L. plantarum ATCC 14917 in the alkali group. All these findings revealed that alkali stress could limit the acid environment formation of L. plantarum 14917 in the fermentation process; however, low acid pH is more suitable for the growth of L. plantarum.

Effects of oligosaccharides on the fermentation properties of Lactobacillus plantarum.

In the present work, we studied the effects of different oligosaccharides on Lactobacillus plantarum ATCC14917, focusing on growth and adhesion characteristics and fermented milk flavor. The results showed that mannan-oligosaccharide (MOS) had the greatest proliferative effect on L. plantarum ATCC14917 in vitro. In terms of adhesive properties, the autoaggregation rate of L. plantarum cultured in MOS was 23.76%, adhesion to mucin was 24.65%, and adhesion to Caco-2 cells was 14.71%. These results for L. plantarum cultured with MOS were higher than those for L. plantarum cultured in fructo-oligosaccharides (FOS) or galacto-oligosaccharides (GOS). Furthermore, the surface consistency and viscosity scores of fermented milk of the MOS group was higher than that of milks cultured with FOS or GOS, although MOS had the lowest scores for fermented milk flavor.

Adhesion-Related Immunomodulatory Activity of the Screened Lactobacillus plantarum from Sichuan Pickle.

Lactic acid bacteria are the majority fermentation starter in the traditional fermented foods. In this research, a promising Lactobacillus plantarum was isolated from Sichuan pickle and its adhesion properties were analyzed in simulated gastrointestinal fluid with different methods. Meanwhile, the immunomodulatory effect of this strain was also evaluated in the Caco-2 cells. Results found that adhesion-related mub genes and other genes like lsp and tuf were upregulated in different culture times. Furthermore, L. plantarum cultured at alkaline environment revealed some anti-inflammation activity through inhibited expression of cytokine IL-8 and increased expression of anti-inflammatory cytokine IL-10 in Caco-2 cells. The texture of yogurt after fermented by this kind of isolated strain was also investigated, which provides the foundation for the further development and application of this kind of strain in food production. More investigations need to be carried out to determine whether this probiotic contributes to regulation of intestinal flora and prevention of gut inflammation.

Structure and immunomodulatory activity of a recombinant mucus-binding protein of Lactobacillus acidophilus.

AIM: The role of mucus-binding protein (MUB) on the adhesion activity and immunomodulatory effect of Lactobacillus acidophilus. MATERIALS & METHODS: The current research mainly focuses on the adhesion and immune function of MUB from L. acidophilus. The structural characteristics and adhesion properties of MUB were analyzed in the intestinal cell models. RESULTS: MUB can promote the aggregation and formation of a membrane-like morphology in L. acidophilus, which could increase the survival rate of L. acidophilus in gastrointestinal tract (GIT). Furthermore, MUB could trigger immune regulation and intestinal protection through the Toll-like receptor 4 (TLR4) signaling pathway and inhibit the activation of mitogen-activated protein kinase (MAPK) signaling pathway. CONCLUSION: MUB of L. acidophilus is an important component involved in bacterial-mucus interactions and immunomodulatory effect in gastrointestinal tract.

Metabolomics analysis of Lactobacillus plantarum ATCC 14917 adhesion activity under initial acid and alkali stress.

The adhesion ability of Lactobacillus plantarum affects retention time in the human gastro-intestinal tract, as well as influencing the interaction with their host. In this study, the relationship between the adhesion activity of, and metabolic changes in, L. plantarum ATCC 14917 under initial acid and alkali stress was evaluated by analyzing auto-aggregation, protein adhesion and cell adhesion in vitro. Based on scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis, the morphology of the bacteria became thickset and the thickness of their cell walls decreased under initial alkali stress. The fold changes of auto-aggregation, adhere to mucin and HT-29 cell lines of L. plantarum ATCC 14917 in the acid group were increased by 1.141, 1.125 and 1.156, respectively. But decreased significantly in the alkali group (fold changes with 0.842, 0.728 and 0.667). Adhesion-related protein increased in the acid group but declined in the alkali group at the mRNA expression level according to real time polymerase chain reaction (RT-PCR) analysis. The changes in the metabolite profiles of L. plantarum ATCC 14917 were characterized using Ultra-Performance Liquid Chromatography-Electrospray ionization-Quadrupole-Time of Flight-mass spectrometry (UPLS-ESI-Q-TOF-MS). In the alkali group, the content of a lot of substances involved in the energy and amino acid metabolism decreased, but the content of some substances involved in the energy metabolism was slightly increased in the acid group. These findings demonstrate that energy metabolism is positively correlated with the adhesion ability of L. plantarum ATCC 14917. The amino-acids metabolism, especially the amino acids related to pH-homeostasis mechanisms (lysine, aspartic acid, arginine, proline and glutamic acid), showed an obvious effect on the adhesion ability of L. plantarum ATCC 14917. This investigation provides a better understanding of L. plantarum's adhesion mechanisms under initial pH stress.

Proteomics Analysis of the Adhesion Activity of Lactobacillus acidophilus ATCC 4356 Upon Growth in an Intestine-Like pH Environment.

Many health effects of Lactobacillus acidophilus are desirable among these the adhesion ability is vital to enhance the possibility of colonization and stabilization associated with the gut mucosal barrier. In this study, the growth characteristics and the adhesion activity of L. acidophilus in the intestine-like pH environment (pH 7.5) are identified. The number of bacteria adhering to the HT-29 cells is found with a gradual increase trend (pH 5.5-7.5). This also leads to the morphological changes of L. acidophilus after exposure to different pH environments. Furthermore, with the help of the isobaric tags for relative and absolute quantification (iTRAQ) proteomic analysis, 207 proteins are detected differentially expressed at pH of 7.5. The use of GO analysis and KEGG analysis indicates three essential pathways related to the cell envelope peptide-glycan biosynthesis, carbohydrate metabolism, and amino acid metabolism are obviously changed. Adhesion related surface protein fmtB and PrtP are upregulated in pH 7.5 group. While the moonlight proteins like pyruvate kinase, which binds specifically to the mucin layer and inhibits the adhesive activity of L. acidophilus, is found downregulated. These results could be useful to understand the adhesion mechanism of L. acidophilus adapting for the gut mucosal barrier in the intestinal environment.