Milk-derived Lactobacillus with high production of short-chain fatty acids relieves antibiotic-induced diarrhea in mice.

Antibiotic-associated diarrhea (AAD) is a common side effect during antibiotic treatment, and this has warranted research into alternative protocols. In this study, we investigated the potential therapeutic effects of three cohorts, Lactobacillus plantarum KLDS 1.0386, Lactobacillus acidophilus KLDS 1.0901 and a mixed strain of both, on intestinal inflammation, the intestinal mucosal barrier, and microbial community in mice with ampicillin-induced diarrhea. The results showed that Lactobacillus inhibited the activation of the TLR4/NF-κB signaling pathway, decreased the expression of pro-inflammatory cytokines, increased the expression of anti-inflammatory cytokines in the murine intestine, and alleviated the intestinal barrier damage and inflammation induced by ampicillin. In addition, Lactobacillus ameliorates intestinal epithelial barrier damage by increasing the expression of tight junction proteins and aquaporins. After Lactobacillus treatment, the diversity of gut microbiota increased significantly, and the composition and function of gut microbiota gradually recovered. In the gut microbiota, Bacteroidetes and Escherichia Shigella related to the synthesis of short-chain fatty acids (SCFAs) were significantly affected by ampicillin, while Lactobacillus regulates the cascade of the microbial-SCFA signaling pathway, which greatly promoted the generation of SCFAs. Collectively, Lactobacillus showed better results in treating AAD, especially in mixed strains.

Effect of Lactobacillus helveticus exopolysaccharides molecular weight on yogurt gel properties and its internal mechanism.

The processing characteristics of yogurt are closely related to the composition and arrangement of exopolysaccharides (EPS) in lactic acid bacteria (LAB). To fully understand and develop the functional properties of EPS and to study the effect of EPS molecular weight on yogurt and its mechanism, the physicochemical properties of high molecular weight EPS-LH43, medium molecular weight EPS-LH13, and low molecular weight EPS-LH23, as well as the gel properties and protein conformation of yogurt, were determined and analyzed in this experiment. The results indicate that EPS-LH43 and EPS-LH13 are both composed of mannose, rhamnose, galacturonic acid, glucose, and galactose. EPS-LH23 is composed of mannose, galacturonic acid, glucose, and galactose. Their Number-average Molecular Weight is 5.21 × 106 Da, 2.39 × 106 Da and 3.76 × 105 Da, respectively. In addition, all three types of EPS have good thermal stability and can improve the stability of casein. In addition, the analysis of the texture, particle size, potential, water holding capacity, rheology, low field nuclear magnetic resonance, microstructure, and flavor characteristics of yogurt confirmed the relationship between the molecular weight of LAB EPS and the gel properties of yogurt. Fluorescence spectrophotometer and circular dichroism analysis indicate that the different molecular weights of LAB EPS have different effects on protein structure, which is an intrinsic factor leading to significant differences in the gel properties of the three types of fermented milk. These findings provide new references for enhancing the understanding of the structure-activity relationship of EPS and indicate that EPS-LH43 can be used to improve the gel properties of dairy products.

Effect of exopolysaccharides yield and addition concentration of Lactobacillus helveticus on the processing characteristics of fermented milk and its mechanism.

Exopolysaccharides (EPS) yield and added concentration of lactic acid bacteria can greatly affect the processing characteristics of fermented milk. In order to investigate the effects and mechanisms of EPS yield and added concentration on fermented milk, researchers extracted EPS from 50 strains of Lactobacillus helvedicus (L. helvedicus) and selected the two strains with the largest difference in EPS yield (L. helvedicus LH18 and L. helvetigus LH33) for subsequent experiments. The physicochemical properties of EPS-LH18 and EPS-LH33 were analyzed. The gel characteristics and protein conformation of fermented milk were studied by means of texture analyzer, rheometer, scanning electron microscopy, nuclear magnetic resonance machine, fluorescence spectrophotometer and circular dichroism. The results indicate that the monosaccharide compositions of EPS-LH18 and EPS-LH33 are the same and have good thermal stability. The texture and rheological properties of L. helveticus LH18 fermented milk are significantly superior to other fermented milk. The reason is that L. helveticus LH18 EPS has the highest yield, which leads to a denser gel structure, lower surface hydrophobicity and free sulfhydryl content of its fermented milk. According to circular dichroism analysis, ß- sheet and random coil are the internal factors leading to the difference in fermented milk gel. In addition, the fermented milk improved even more favorably as the concentration of the two EPS additions increased. As described above, L. helveticus LH18 has the potential to be an excellent yogurt starter, and both of the above EPS can be used as probiotic stabilizer alternatives for fermented dairy products.

Exopolysaccharides of lactic acid bacteria: Structure, biological activity, structure-activity relationship, and application in the food industry: A review.

Over the past few decades, researchers have discovered that probiotics play an important role in our daily lives. With the further deepening of research, more and more evidence show that bacterial metabolites have an important role in food and human health, which opens up a new direction for the research of lactic acid bacteria (LAB) in the food and pharmaceutical industry. Many LAB have been widely studied because of the ability of exopolysaccharides (EPS). Lactic acid bacteria exopolysaccharides (LAB EPS) not only have great potential in the treatment of human diseases but also can become natural ingredients in the food industry to provide special qualitative structure and flavor. This paper has organized and summarized the biosynthesis, strain selection, production process parameters, structure, and biological activity of LAB EPS, filling in the monotony and incompleteness of previous articles' descriptions of LAB EPS. Therefore, this paper focuses on the general biosynthetic pathway, structural characterization, structure-activity relationship, biological activity of LAB EPS, and their application in the food industry, which will help to deepen people's understanding of LAB EPS and develop new active drugs from LAB EPS. Although the research results are relatively affluent, the low yield, complex structure, and few clinical trials of EPS are still the reasons that hinder its development. Therefore, future knowledge expansion should focus on the regulation of structure, physicochemical properties, function, higher production of EPS, and clinical trial applications, which can further increase the commercial significance and value of EPS. Furthermore, better understanding the structure-function relationship of EPS in food remains a challenge to date.

In vivo evidence of the prevents DSS-induced colitis of Lactiplantibacillus plantarum L15.

Ulcerative colitis (UC) is challenging to treat and severely impacts patients and families. A previous study reported immunomodulatory and reduction of pro-inflammatory properties for the Lactiplantibacillus plantarum L15. This study aimed to analyze the preventive properties and mechanistic actions in an in vivo colitis model. The histopathological alteration, inflammation cytokines, and intestinal barrier function were analyzed. Subsequently, the cecal gut microbiota contents and products from different groups were detected. Finally, gene expressions related to the NF-κB signaling process were evaluated. L. plantarum L15 significantly decreased disease activity index (DAI), myeloperoxidase activity (MPO), pro-inflammatory cytokine (TNF-α, IL-1ß, and IL-6) level, and increased weight change, colon length, and production of inflammation-suppressing cytokines. Furthermore, this strain supplementation substantially increased ZO-1, Occludin, and Claudin-1, and MUC2 mRNA expression levels with a corresponding decrease in serum lipopolysaccharide and D-lactic acid contents. In addition, L. plantarum L15 improved gut microbiota composition and increased short-chain fatty acid (SCFAs) in the colon content, which significantly reduced the transfer of NF-κB p65 to the nucleus. Our findings provide a theoretical basis for L. plantarum L15 as a preventive candidate for UC.

Bifidobacterium longum BL-10 with Antioxidant Capacity Ameliorates Lipopolysaccharide-Induced Acute Liver Injury in Mice by the Nuclear Factor-κB Pathway.

Bifidobacterium longum is frequently utilized and has broad prospects for preventing liver injury. The current research assessed the antioxidant capacity of B. longum BL-10 and probed its mechanism for ameliorating lipopolysaccharide (LPS)-induced acute liver injury (ALI). B. longum BL-10-encoded 15 antioxidant genes showed strong reducing power activity and scavenging activity of DPPH, hydroxyl radicals, and superoxide anions. The intragastric administration of B. longum BL-10 resulting in a marked reduction in liver function indicators (alanine aminotransferase, aspartate aminotransferase, total bilirubin, and total bile acid) and proinflammatory cytokines (TNF-α, IFN-γ, and IL-6) was indicative of ALI recovery. Following 16s RNA analysis, B. longum BL-10 significantly altered the richness of genera, as for the Escherichia-Shigella, Lachnospiraceae_NK4A136_group, and Clostridia_UCG-014, dramatically contributing to the formation of acetic acid and butyric acid. Meanwhile, their metabolites regulated the TLR4/NF-κB signaling pathways to alleviate hepatic injury symptoms. Overall, all the results demonstrated that B. longum BL-10 had excellent efficiency in preventing LPS-induced ALI.

Immunomodulatory effects of mixed Lactobacillus plantarum on lipopolysaccharide-induced intestinal injury in mice.

The intestine is the largest digestive and immune organ in the human body, with an intact intestinal mucosal barrier. Lactobacillus plantarum is an important strain of probiotics in the intestine for boosting intestinal immunity to defend against intestinal injury. In the lipopolysaccharide-induced intestinal injury model, mixed L. plantarum (L. plantarum KLDS 1.0318, L. plantarum KLDS 1.0344, and L. plantarum KLDS 1.0386) was suggested to boost intestinal immunity. In detail, compared with LPS-induced mice, mice in the mixed L. plantarum group showed significantly reduced intestine (jejunum, ileum, and colon) tissue injury, pro-inflammatory cytokine (TNF-α, IL-6 and IL-12) levels, myeloperoxidase activities, and serum D-lactate (P < 0.05) content. Moreover, the mixed L. plantarum significantly increased the number of immunocytes (CD4+ T cells, IgA plasma cells) and the expression of tight junction proteins (Claudin1 and Occludin). The results also showed that the mixed L. plantarum significantly down-regulated (P < 0.05) the intestinal protein expression of TLR4, p-IκB, and NF-κB p65. The mixed L. plantarum group increased the relative abundance of the genera, including Lactobacillus, Lachnoclostridium, and Desulfovibrio, which are related to improving the levels of SCFAs (acetic acid, butyric acid) and total bile acid (P < 0.05). Overall, these results indicated that the mixed L. plantarum had great functionality in reducing LPS-induced intestinal injury.