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Metabolizing ellagic acid (EA) to urolithin A with numerous bioactivities significantly improve the nutritional value of food rich in EA. In the present study, Streptococcus thermophilus FUA329 was applied to prepare pomegranate juice yogurt. The best process formula was investigated through single-factor experiments and response surface methodology. With S. thermophilus CGMCC1.8748 as control, the viability of strain, rheological properties and antioxidant activity of pomegranate juice yogurt fermented with strain FUA329 were evaluated. The content of urolithin A in pomegranate juice yogurt fermented with strain FUA329 were analyzed by high-performance liquid chromatography. The results showed that the optimal fermentation conditions for preparing pomegranate juice yogurt by S. thermophilus FUA329 were 15.79% pomegranate juice content, 7.08% sucrose content and 3.04% starter inoculum size, fermentation at 37 °C for 7 h and comprehensive sensory score was 79.4 points. Under the optimal conditions, the results of basic indicators showed that yogurt acidity was (82.5±1.3)°T, whey precipitation was 9.6%±0.97%, color difference was 68.17±2.75, bacterial activity was 2.01±0.31 (OD600). In terms of antioxidant activity, DPPH radical, ABTS+ radical and superoxide anion radical scavenging rates of fermented pomegranate juice yogurt by strain FUA329 were 82.87%±1.48%, 88.20%±2.10% and 76.92%±1.02%, respectively, which was significantly better than plain yogurt fermented by strain FUA329 and pomegranate juice yogurt fermented by S. thermophilus CGMCC1.8748. In addition, urolithin A content was 3.31 μmol/L in fermented pomegranate juice yogurt by strain FUA329 after 7 h. The results of this study would provide a theoretical basis for fermenting a functional pomegranate juice yogurt, and lay a foundation for the development and utilization of S. thermophilus FUA329. [ABSTRACT FROM AUTHOR]

In order to evaluate the effect of Streptococcus thermophilus fermentation on green tea extract and its storage characteristics, this study used Streptococcus thermophilus FUA329 and S. thermophilus ST1.8748 (control group) to conduct experiments on green tea extracts. After fermentation and storage at 4 °C for 0, 30, 60, 120 and 180 d, pH, viable bacterial count, tea polyphenol content, ellagic acid content, and urolithin A content were used as the main evaluation indicators, combined with anti-oxidation activity to evaluate the storage quality of fermented green tea extract. The results showed that compared with the S. thermophilus ST1.8748 control group, the pH of S. thermophilus FUA329 fermented green tea extract during the storage period was between 5.39 and 5.71. The highest number of viable bacteria at 48 h was 9.97x108 CFU/mL. The content of tea polyphenols gradually decreased and the ellagic acid content tended to be stable. Urolithin A was produced at 48 h, and its concentration was 0.664 μmol/L. The antioxidant activity was always maintained at a high level. In summary, S. thermophilus FUA329 fermented green tea extract can significantly delay the quality decline and nutrient loss of green tea extract during storage. [ABSTRACT FROM AUTHOR]

Urolithin A, a metabolite of ellagic acid, has many beneficial biological activities for people. Strains capable of producing urolithin A from ellagic acid have the hope of becoming the next-generation probiotics. However, only a few species of these strains have been reported. In this study, FUA329, a strain capable of converting ellagic acid to urolithin A in vitro, was isolated from the breast milk of healthy Chinese women. The results of morphological observation, physiological and biochemical tests, and 16S rRNA gene sequence analysis confirmed that the strain FUA329 was Streptococcus thermophilus. In addition, the S. thermophilus FUA329 growth phase is consistent with the degradation of ellagic acid, and urolithin A was produced in the stationary phase, with a maximum concentration of 7.38 μM at 50 h. The corresponding conversion efficiency of urolithin A from ellagic acid was 82%. In summary, S. thermophilus FUA329, a novel urolithin A-producing bacterium, would be useful for the industrial production of urolithin A and may be developed as a next-generation probiotic. [ABSTRACT FROM AUTHOR]

Dietary polyphenol ellagic acid has anti-cancer and anti-inflammatory activities, and these biological activities require the conversion of ellagic acid to urolithins by intestinal microbes. However, few gut microbes are capable of metabolizing ellagic acid to produce urolithins, limiting the beneficial effects of ellagic acid on health. Here, we describe an intestinal bacterium Lactococcus garvieae FUA009 isolated from the feces of a healthy volunteer. It was demonstrated via HPLC and UPLC-MS analysis that the end product of ellagic acid metabolism of FUA009 was urolithin A. In addition, we also examined the whole genome sequence of FUA009 and then assessed the safety and probiotic properties of FUA009 based on a complete genome and phenotype analysis. We indicated that FUA009 was safe, which was confirmed by FUA009 being sensitive to multiple antibiotics, having no hemolytic activity, and being free of aggressive putative virulence factors. Moreover, 19 stress-responsive protein genes and 8 adhesion-related genes were predicted in the FUA009 genome. Furthermore, we demonstrated that FUA009 was tolerant to acid and bile salt by determining the cell viability in a stress environment. In summary, Lactococcus garvieae FUA009, as a novel UA-producing bacterium, not only contributes to the study of the metabolic pathway of ellagic acid but is also expected to be a novel probiotic candidate. [ABSTRACT FROM AUTHOR]

Streptococcus thermophilus FUA329, a urolithin A-producing bacterium, is isolated from human breast milk. The complete genome sequence of FUA329 did not contain any plasmids and at least 20 proteins were related to extreme environment resistance. Phenotypic assay results demonstrated that FUA329 was susceptible to 12 kinds of antibiotics and did not exhibit any hemolytic or nitrate reductase activity. Three free radical scavenging assays revealed that FUA329 have high antioxidant capability. FUA329 exhibited a cell surface hydrophobicity of 52.58 ± 1.17% and an auto-aggregation rate of 18.69 ± 2.48%. Moreover, FUA329 demonstrated a survival rate of over 60% in strong acid and bile salt environments, indicating that FUA329 may be stable colonization in the gastrointestinal tract. Additionally, we firstly found 3 potential proteins and 11 potential genes of transforming ellagic acid to urolithins in FUA329 genome. The above results indicate that FUA329 has credible safety and probiotic properties, as well as the potential to be developed as a new generation of urolithin A-producing probiotics. [Display omitted] • The genome of S. thermophilus FUA329 was sequence and analyzed. • The genome sequence of FUA329 includes safety and probiotic characteristics-related genes. • Phenotypic assay revealed FUA329 has credible safety and good tolerance to extreme environments. • Eleven potential genes for transforming ellagic acid to urolithins are located in the FUA329 genome. [ABSTRACT FROM AUTHOR]