Nutritional Content Dynamics and Correlation of Bacterial Communities and Metabolites in Fermented Pickled Radishes Supplemented With Wheat Bran.

Wheat bran supplementation in cereal food processing improves the nutritional value and quality of the final products. However, whether wheat bran has the potential as a biofortifier to enhance nutritional and flavor of fermented vegetables remains unknown. The study aimed to evaluate the potential of wheat bran supplementation for nutrition and flavor fortification during radish fermentation, and to explore the role of microorganisms in nutritional and flavor development. Using high-throughput sequencing coupled with high-performance liquid chromatography and headspace solid-phase microextraction-gas chromatography-mass spectrometry, the microbial community profiles and nutritional and flavor changes of wheat bran-treated samples were analyzed and compared with control samples. Correlation analysis between bacteria taxa with metabolites were also performed. The results showed that wheat bran treatment increased the content of most free amino acids (FAAs), α-linolenate, thiamine, and riboflavin in the samples (p < 0.05). In addition, the increased consumption of reducing sugar and glutamate in the wheat bran-treated samples was due to the production of secondary metabolites such as lactic acid, ethanol, acetic acid, and GABA (p < 0.05). Moreover, compared with control samples, the flavor of the wheat bran-treated pickled radish was preferable. Wheat bran increased the amount of alcohol, ester, acid, and ketones compounds but reduced the number of sulfides, which increased the aroma but decreased the pungent flavor. Additionally, the correlation analysis suggested that Lactobacillus, the most dominant genus, was boosted by wheat bran and was positively associated with most of FAAs, GABA, and lactate, while negatively associated with most sulfides. Therefore, compared with the control, wheat bran treatment could improve the nutritional values and sensorial properties of radish pickles. New areas of research should explore the co-fermentation of other vegetables with wheat bran, and the potential of this processing technique to provide consumers with products of high nutritional quality.

Comparative Evaluation of the Phytochemical Profiles and Antioxidant Potentials of Olive Leaves from 32 Cultivars Grown in China.

Olives (Olea europaea L.) are a significant part of the agroindustry in China. Olive leaves, the most abundant by-products of the olive and olive oil industry, contain bioactive compounds that are beneficial to human health. The purpose of this study was to evaluate the phytochemical profiles and antioxidant capacities of olive leaves from 32 cultivars grown in China. A total of 32 phytochemical compounds were identified using high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry, including 17 flavonoids, five iridoids, two hydroxycinnamic acids, six triterpenic acids, one simple phenol, and one coumarin. Specifically, olive leaves were found to be excellent sources of flavonoids (4.92-18.29 mg/g dw), iridoids (5.75-33.73 mg/g dw), and triterpenic acids (15.72-35.75 mg/g dw), and considerable variations in phytochemical content were detected among the different cultivars. All tested cultivars were classified into three categories according to their oil contents for further comparative phytochemicals assessment. Principal component analysis indicated that the investigated olive cultivars could be distinguished based upon their phytochemical profiles and antioxidant capacities. The olive leaves obtained from the low-oil-content (<16%) cultivars exhibited higher levels of glycosylated flavonoids and iridoids, while those obtained from high-oil-content (>20%) cultivars contained mainly triterpenic acids in their compositions. Correspondingly, the low-oil-content cultivars (OL3, Frantoio selection and OL14, Huaou 5) exhibited the highest ABTS antioxidant activities (758.01 ± 16.54 and 710.64 ± 14.58 mg TE/g dw, respectively), and OL9 (Olea europaea subsp. Cuspidata isolate Yunnan) and OL3 exhibited the highest ferric reducing/antioxidant power assay values (1228.29 ± 23.95 mg TE/g dw and 1099.99 ± 14.30 mg TE/g dw, respectively). The results from this study may be beneficial to the comprehensive evaluation and utilization of bioactive compounds in olive leaves.

Citrobacter freundii causing Ginger (Zingiber officinale Rosc.) Rot in Tangshan, China.

Ginger (Zingiber officinale Rosc.) is an important economic crop and its rhizome can be used as seasoning agent and traditional medicine in China. During July 2018 and 2019, decay symptoms occurred in the ginger planting area of Tangshan City, Hebei Province, with incidence rates of 15%～20%. The pathogen infected the rhizomes and leaves. The symptoms included leaves chlorosis and gradually wilting, even the whole plant wilted, the rhizome became soft and presented light brown maceration. In serious cases, the interior of rhizome was completely eroded, gray-white juice overflowing the epidermis, and with foul smell. The rhizome surfaces of ginger plants were disinfected with 1% NaOCl, and colonies were isolated and purified on nutrient agar (NA) solid medium by streaking. Eight isolates were obtained from 15 diseased tissue samples. Further morphological, physiological and biochemical identification of the pure cultured bacteria were carried out. Three strains of bacteria were picked for further analysis. All of the three strains were gram-negative, short rod-shaped，nonmotile bacillus. Colonies were round and milky yellow, smooth raised, and moist after incubation at 28°C for 24h on NA. Physiological and biochemical test results showed that strains were facultatively anaerobic, negative for indole, methyl red, the Voges-Prauskauer test (V-P) and urease; positive for glucose, sucrose, sorbitol, inositol, mannitol, citrate utilization and hydrogen sulfide production; gelatin liquefaction. A typical hypersensitive reaction was induced on 12-week-old tobacco (Nicotiana benthamiana) leaves, which were inoculated by injecting suspensions of the isolated strain (108 CFU/mL) at 25 ℃ after 24h. These characteristics were consistent with Citrobacter freundii (Werkman and Gillen 1932). To further assess the identity of the strains, the genomic DNA was extracted from one bacterium（JXJ4）. The partial 16S rRNA region (Lane 1991) and specific rpoB and gyrB genes (Mollet et al. 1997, Brady et al. 2013) were amplified and sequenced with primers 27F/1492R, CM7/CM31b and UP1f/UP2r, respectively. The obtained 16S, rpoB and gyrB sequences (GenBank accession MN148645, MN158728 and MW199734) of the isolate showed 99.93%, 99.51% and 99.82% identity to the corresponding sequences of C. freundii in GenBank (CP024679.1, CP024677.1 and KM509081.1). Maximum likelihood analysis was performed, and the phylogenetic tree clustered with C. freundii (MEGAX, Bootstrap n=1000). The pathogenicity of the isolates was tested on ginger plants and rhizomes tissue. The bacterial suspensions (108 CFU/mL) of three isolates were injected into the basal stem and rhizomes center of 9 healthy ginger seedlings respectively, and Control groups were treated with sterile water. The inoculated plants were kept in a moist chamber (28°C, 16-h light and 8-h dark period) and ginger rhizomes were placed in the incubator (30°C, 16-h light and 8-h dark period). Seven days after inoculation, the ginger tubers showed symptoms of decay, and 20 to 25 days later, the ginger plant leaves browned and died. The pathogenicity test was repeated 4 times and all controls were healthy. Pathogens were reisolated from symptomatic plants and rhizomes and identified as C. freundii based on the morphological, biochemical and molecular methods described previously, fulfilling Koch's hypothesis. To our knowledge, this is the first report of ginger rot caused by C. freundii in China.

Effect of chitooligosaccharides on human gut microbiota and antiglycation.

Chitooligosaccharides (COS) have garnered great attention in the field of human healthcare. The prebiotic activities and antiglycation of COS were investigated using a combination of in vitro and in vivo studies. COS supplementation dramatically increased the levels of acetic acid, while reducing the concentrations of propionic and butyric acids. It also decreased the total bacterial population; however, it did not affect diversity and richness of the gut microbiota. In addition, COS modulated the gut microbiota composition by increasing Bacteroidetes, decreasing Proteobacteria and Actinobacteria, and lowering the Firmicutes/Bacteroidetes ratio. COS promoted the generation of beneficial Bacteroides and Faecalibacterium genera, while suppressing the pathogenic Klebsiella genus. The antiglycation activity of COS and acetic acid was dose-dependent. Furthermore, COS prevented the decrease of serum Nε-(carboxymethyl) lysine (CML) level caused by CML ingestion in a mouse model of diet-induced obesity. To improve host health, COS could be potential prebiotics in food products.

Treatment with Subcritical Water-Hydrolyzed Citrus Pectin Ameliorated Cyclophosphamide-Induced Immunosuppression and Modulated Gut Microbiota Composition in ICR Mice.

Subcritical water can effectively hydrolyze pectin into smaller molecules while still maintaining its functional regions. Pectic heteropolysaccharide can mediate immune regulation; however, the possible effects of subcritical water-hydrolyzed citrus pectin (SCP) on the immune response remain unclear. Therefore, the effects of SCP on immunomodulatory functions and intestinal microbial dysbiosis were investigated using a cyclophosphamide-induced immunosuppressed mouse model. In this research, immunosuppressed ICR mice were administrated with SCP at dosages of 300/600/1200 mg/kg.bw by oral gavage, and body weight, immune organ indexes, cytokines, and gut microbiota were determined. The results showed that subcritical water treatment decreased the molecular mass and increased the content of galacturonic acid in citrus pectin hydrolysates. Meanwhile, the treatment with SCP improved immunoregulatory functional properties and bioactivities over the original citrus pectin. For example, SCP protected immune organs (accelerated recovery of immune organ indexes) and significantly enhanced the expression of immune-related cytokines (IL-2, IL-6, IFN-γ, and TNF-α). The results of the 16S rDNA sequencing analysis on an IlluminaMiSeq platform showed that SCP normalized Cy-induced gut dysbiosis. SCP ameliorated Cy-dependent changes in the relative abundance of several taxa, shifting the balance back to normal status (e.g., SCP increased beneficial Muribaculaceae, Ruminococcaceae, Bacteroidaceae, and Prevotellaceae while decreasing pathogenic Brevundimonas and Streptococcus). The results of this study suggest an innovative application of citrus pectin as an immunomodulator.

Daily Supplementation with Fresh Angelica keiskei Juice Alleviates High-Fat Diet-Induced Obesity in Mice by Modulating Gut Microbiota Composition.

SCOPE: Angelica keiskei is associated with several health benefits, but little is known about the effect of A. keiskei juice (AKJ), which is rich in polyphenols, coumarins, and other healthful agents, on high-fat diet-induced obesity or its relationship with intestinal microbiota composition changes. METHODS AND RESULTS: C57BL/6 mice are fed either a normal diet (ND group; n = 8), a high-fat diet (HFD group; n = 8), or a high-fat diet supplemented with AKJ (AKJ group; n = 8) for 10 weeks. The results show that AKJ prevents weight gain, lowered fat accumulation, blood glucose, serum lipid levels, hepatic steatosis, and modulates the level of expression of genes involved in lipid metabolism in mice with obesity. AKJ is found to normalize HFD-induced gut dysbiosis. Particularly, AKJ ameliorates HFD-dependent changes in the relative abundance of several taxa back to normal status (e.g., AKJ increased Bacteroides and decreased Mollicutes_RF9, Ruminococcaceae_UCG-014, Faecalibacterium, and Lactobacillus). Spearman's correlation analysis reveals that those genera are closely correlated with body weight, fasting serum glucose, and serum lipid levels. CONCLUSION: The results show that consumption of phytochemical-rich AKJ may prevent HFD-induced obesity and metabolic disorders via changes in metabolic genes and gut microbiota composition.

Extract of ice plant (Mesembryanthemum crystallinum) ameliorates hyperglycemia and modulates the gut microbiota composition in type 2 diabetic Goto-Kakizaki rats.

Ice plant (Mesembryanthemum crystallinum) extract (IPE) is a rich source of d-pinitol, which is widely known to have potential anti-diabetic effects. In the present study, response surface methodology (RSM) was used to optimize d-pinitol extraction conditions with the Box-Behnken design. We then evaluated the anti-diabetic effects properties of IPE that was extracted under optimized conditions (53 °C, 119 min extraction time, and 1 : 11 dilution) in type 2 diabetic Goto-Kakizaki (GK) rats. IPE (400 mg kg-1 day-1) effectively controlled the increased fasting blood glucose level (decreased by 45% vs. GK-control rats) and impaired glucose tolerance (decreased area under curve (AUC) of glucose values by 24%, p < 0.05 vs. GK-control rats) after eight weeks of treatment. Furthermore, IPE significantly improved pancreatic islet morphology, ß-cell survival, and insulin secretion in diabetic rats, thus contributing to the antihyperglycemic effect. Finally, prebiotic effects of IPE on gut microbiota were observed and included increased abundance of the beneficial bacteria Bacteroidales_S24-7 and Ruminococcaceae_UCG-014 and decreased abundance of Treponema_2 and Lactobacillus. Overall, IPE has a substantial effect on attenuating hyperglycemia and modulating gut microbiota composition in diabetic GK rats. Therefore, IPE might be a promising functional food for the prevention of diabetes.