Yanping Wang

Lactobacillus kefiranofaciens, a lactic acid bacterium isolated from kefir grains, has various probiotic functions, including antioxidant activity, improvement of intestinal health, and immunomodulation. However, the effect of its postbiotic on immune modulation has been rarely reported. In this study, the immunomodulatory activities of the Lactobacillus kefiranofaciens ZW18 postbiotic (Post-ZW18) were investigated both in vitro and in vivo. We discovered that Post-ZW18 increased the phagocytosis of RAW264.7 cells (P > 0.05) and promoted the secretion of cytokines, including NO, IL-6, and TNF-α (P < 0.05), thereby activating the immune response in macrophages in vitro. In vivo, Post-ZW18 reversed cyclophosphamide (CTX)-induced weight loss and organ damage in immunosuppressed mice (P < 0.05), and enhanced the immune response by activating the TLR2/NF-κB signaling pathway, promoting T cell activation and differentiation, and modulating the production of cytokines such as TNF-α, IL-6, and INF-γ (P < 0.05). Furthermore, Post-ZW18 remodeled the intestinal flora, increased the Firmicutes/Bacteroidetes (F/B) ratio (P > 0.05), and upregulated the abundance of bacteria associated with immune activation, specifically increasing unclassified_Lachnospiraceae, Odoribacter, and Lachnospiraceae_NK4A136_group (P < 0.05). In summary, this study provided evidence that Post-ZW18 may serve as a novel dietary supplement for immune regulation.

In this study, Lactiplantibacillus plantarum BC299, Lactobacillus delbrueckii subsp. bulgaricus 717 and Streptococcus thermophilus 176 were used as combined starter cultures to produce a fermented soy whey beverage. The results showed that the fermentation of the combined starter cultures increased the content of lactic acid, acetic acid, succinic acid, and malic acid, while decreased the content of citric acid, fumaric acid and propionic acid. Meanwhile, the fermentation also effectively changed the proportion of volatile flavor substances. The higher sensory score of the fermented soy whey also confirmed the flavor improvement effect of the combined starter cultures. In addition, the in vivo results of animal experiments showed that the fermented soy whey could significantly improve the disease activity index (DAI) and colon morphology in dextran sulfate sodium (DSS) induced colitis mice. This study showed that the combined lactic acid bacteria starter cultures had important value-added relevance on the effective reuse of the soy whey by-product.

Kombucha, which is rich in tea polyphenols and organic acid, is a kind of acidic tea soup beverage fermented by acetic acid bacteria, yeasts, lactic acid bacteria. Kombucha has been reported to possess anti-diabetic activity, but the underlying mechanism was not well understood. In this study, a high-fat, high-sugar diet combined with streptozotocin (STZ) injection was used to induce T2DM model in mice. After four weeks of kombucha intervention, the physiological and biochemical index were measured to determine the diabetes-related indicators. High-throughput sequencing technology was used to analyze the changes in gut microbiota from the feces. The results showed that four weeks of kombucha intervention increased the abundance of SCFAs-producing bacteria and reduced the abundance of gram-negative bacteria and pathogenic bacteria. The improvement in gut microbiota reduced the damage of intestinal barrier, thereby reducing the displacement of lipopolysaccharide (LPS) and inhibiting the occurrence of inflammation and insulin resistance in vivo. In addition, the increased levels of SCFAs-producing bacteria, and thus increasing the SCFAs, improved islet β cell function by promoting the secretion of gastrointestinal hormones (GLP-1/PYY). This study methodically uncovered the hypoglycemic mechanism of kombucha through gut microbiota intervention, and the result suggested that kombucha may be introduced as a new functional drink for T2DM prevention and treatment.

Non-alcoholic fatty liver disease (NAFLD) has become a highly concerned health issue in modern society. Due to the attentions of probiotics in the prevention of NAFLD, it is necessary to further clarify their roles. In this study, the methionine and choline-deficient (MCD) diet induced NAFLD rats model were constructed and treated with strain L. plantarum MA2 by intragastric administration once a day at a dose of 1 × 10⁸ cfu/g.bw. After 56 days of the therapeutic intervention, the lipid metabolism and the liver pathological damage of the NAFLD rats were significantly improved. The content of total cholesterol (TC) and total triglyceride (TG) in serum were significantly lower than that in the NAFLD group (p < 0.05). Meanwhile, the intestinal mucosal barrier and the structure of intestinal microbiota were also improved. The villi length and the expression of claudin-1 was significantly higher than that in the NAFLD group (p < 0.05). Then, by detecting the content of LPS in the serum and the LPS-TLR4 pathway in the liver, we can conclude that Lactobacillus plantarum MA2 could reduce the LPS by regulating the gut microecology, thereby inhibit the activation of LPS-TLR4 and it downstream inflammatory signaling pathways. Therefore, our studies on rats showed that L. plantarum MA2 has the potential application in the alleviation of NAFLD. Moreover, based on the application of the strain in food industry, this study is of great significance to the development of new therapeutic strategy for NAFLD.

Summary: It is well known that probiotics are effective in relieving inflammatory bowel disease (IBD). However, their exact mechanism is still unclear. Herein, we evaluated the effect of novel Lactobacillus plantarum BC299 on dextran sodium sulphate (DSS)‐induced colitis model mice and investigated the molecular mechanism. We found BC299 could regulate immune response and reduce immunosuppression by enhancing the expression of Th1 T cells in cyclophosphamide‐induced immunosuppressive model mice. Meanwhile, DSS‐induced colitis model mice were furtherly constructed. The results displayed BC299 can restore bodyweight and relieve colon morphology of colitis mice. Real‐time quantitative polymerase chain reaction results demonstrated BC299 can regulate immune response by reducing the expression of TNF‐α and IL‐1β mRNA and increasing the expression of IL‐10 and TGF‐β mRNA. Moreover, BC299 administration reshaped and increased the diversity of gut microbiota in IBD mice. Therefore, BC299 can alleviate colitis by regulating immune response and modulating gut microbiota.

Lactic acid bacteria are a kind of microorganisms that can ferment carbohydrates to produce lactic acid, and are currently widely used in the fermented food industry. In recent years, with the excellent role of lactic acid bacteria in the food industry and probiotic functions, their microbial metabolic characteristics have also attracted more attention. Lactic acid bacteria can decompose macromolecular substances in food, including degradation of indigestible polysaccharides and transformation of undesirable flavor substances. Meanwhile, they can also produce a variety of products including short-chain fatty acids, amines, bacteriocins, vitamins and exopolysaccharides during metabolism. Based on the above-mentioned metabolic characteristics, lactic acid bacteria have shown a variety of expanded applications in the food industry. On the one hand, they are used to improve the flavor of fermented foods, increase the nutrition of foods, reduce harmful substances, increase shelf life, and so on. On the other hand, they can be used as probiotics to promote health in the body. This article reviews and prospects the important metabolites in the expanded application of lactic acid bacteria from the perspective of bioengineering and biotechnology.

Summary: The Maillard reaction products (MRPs) from chicken protein hydrolysate were demonstrated to have intense umami and kokumi‐enhancing effects. To find the main flavour‐enhancing compounds in the chicken protein hydrolysate, the fractions with different molecular weights were obtained by ultrafitration. The evaluation of taste characteristics revealed that the fractions with molecular weights ranging from 1000 to 5000 Da predominantly contributed to the umami and kokumi‐enhancing effects. After further purification by using ultrafiltration, gel filtration chromatography, and ultra‐high performance liquid chromatography‐tandem mass spectrometry (UPLC‐MS/MS) in combination with sensory evaluation, three peptides were identified, an octapeptide (WVNEEDHL), a nonapeptide (NSLEGEFKG) and a decapeptide (KDLFDPVIQD). Sensory evaluation results showed that all three peptides could significantly enhance the meat flavour, umami taste and thickness of the chicken powder solution. The results indicate that the peptides have potential application as effective chicken flavour‐enhancing ingredients in the food industry.

Increasing evidence indicates that probiotics can effectively improve depression-like behavior. However, the underlying mechanism is still unclear. In this study, the antidepressant effect of Lactobacillus kefiranofaciens CGMCC2809 (ZW3) isolated from Tibetan Kefir grains was investigated using a mouse model of chronic unpredictable mild stress (CUMS). ZW3 improved depression-like behavior and independent exploration ability in the CUMS group. Moreover, ZW3 regulated biochemical disorders in the hypothalamic–pituitary–adrenal axis, immune system and tryptophan metabolism caused by stress. Furthermore, ZW3 could modulate the composition of the gut microbiota, and alleviate constipation by improving the fecal water content in stressed mice. We found that the probiotic strain was present in the whole intestine, even 7 days after its administration was stopped. These results suggest that L. kefiranofaciens ZW3 might improve depression by regulating the gut microbiota as a probiotic food.

The sensory characteristics of Maillard reaction products from chicken protein hydrolysates (MRP-CPHs) at different degrees of hydrolysis (DH) were evaluated using descriptive sensory analysis. Five characteristics (boiled chicken flavor, umami, mouthfulness, continuity and overall acceptance) of the MRP-CPHs were evaluated. In addition, the changes in free amino acid contents and molecular weight distribution of chicken protein hydrolysates (CPHs) were also determined. The results showed that the sensory attributes were affected by DH of the CPHs, there was a distinct difference among the MRP-CPHs of almost all sensory attributes. The Maillard reaction product with a hydrolysis time of 3 h showed the strongest in the mouthfulness, boiled chicken flavor, and overall acceptance. These results indicated that the CPHs with a DH range from 15.80% to 18.64% (hydrolysis time range from 3 to 6 h) might be a desirable precursor for the production of chicken flavor in the food industry.