One-step duplex RT-droplet digital PCR assay for the detection of norovirus GI and GII in lettuce and strawberry.

The study was designed to develop a sensitive one-step duplex reverse transcription droplet digital polymerase chain reaction (RT-ddPCR) to detect norovirus genogroup I and II (NoV GI and GII) in lettuce and strawberry. The specificity, sensitivity, repeatability and robustness of the assay was compared with RT-qPCR. The lowest concentration detected by RT-ddPCR for NoV GI and NoV GII were 4.68 and 8.47 copies/µL respectively, much lower than that of RT-qPCR with a number of 46.8 and 84.7 copies/µL, respectively. Lettuce and strawberry samples were artificially contaminated with NoV GI and GII suspensions, with inoculum size of 3.00 × 106 to 1.70 × 108 copies and 4.80 × 105 to 2.50 × 107 copies, respectively. Strawberry spiked with low inoculum size revealed positive results by RT-ddPCR, while recorded negative by RT-qPCR. Meanwhile, RT-ddPCR also showed a higher average recovery rate for NoV in lettuce and strawberry than RT-qPCR.The limit of detection (LoDs) of RT-ddPCR for NoVs in lettuce was 2.32 × 104 copies/25g (NoV GI) and 2.36 × 104 ciopies/25g (NoV GII), and that in strawberry was 2.56 × 104 copies/25g (NoV GI) and 2.64 × 104 ciopies/25g (NoV GII), which were 10 folds lower than that of RT-qPCR. The developed duplex RT-ddPCR assay exhibited stability and increased capacity to resist inhibitors in food samples with low concentration of NoV, making it a reliable method to avoid false negative result as opposed to RT-qPCR. In conclusion, one-step RT-ddPCR method developed in this study is pertinent in detecting foodborne virus such as NoV.

Substrate Use Prioritization by a Coculture of Five Species of Gut Bacteria Fed Mixtures of Arabinoxylan, Xyloglucan, ß-Glucan, and Pectin.

Dietary fiber provides growth substrates for bacterial species that belong to the colonic microbiota of humans. The microbiota degrades and ferments substrates, producing characteristic short-chain fatty acid profiles. Dietary fiber contains plant cell wall-associated polysaccharides (hemicelluloses and pectins) that are chemically diverse in composition and structure. Thus, depending on plant sources, dietary fiber daily presents the microbiota with mixtures of plant polysaccharides of various types and complexity. We studied the extent and preferential order in which mixtures of plant polysaccharides (arabinoxylan, xyloglucan, ß-glucan, and pectin) were utilized by a coculture of five bacterial species (Bacteroides ovatus, Bifidobacterium longum subspecies longum, Megasphaera elsdenii, Ruminococcus gnavus, and Veillonella parvula). These species are members of the human gut microbiota and have the biochemical capacity, collectively, to degrade and ferment the polysaccharides and produce short-chain fatty acids (SCFAs). B. ovatus utilized glycans in the order ß-glucan, pectin, xyloglucan, and arabinoxylan, whereas B. longum subsp. longum utilization was in the order arabinoxylan, arabinan, pectin, and ß-glucan. Propionate, as a proportion of total SCFAs, was augmented when polysaccharide mixtures contained galactan, resulting in greater succinate production by B. ovatus and conversion of succinate to propionate by V. parvula Overall, we derived a synthetic ecological community that carries out SCFA production by the common pathways used by bacterial species for this purpose. Systems like this might be used to predict changes to the emergent properties of the gut ecosystem when diet is altered, with the aim of beneficially affecting human physiology.IMPORTANCE This study addresses the question as to how bacterial species, characteristic of the human gut microbiota, collectively utilize mixtures of plant polysaccharides such as are found in dietary fiber. Five bacterial species with the capacity to degrade polymers and/or produce acidic fermentation products detectable in human feces were used in the experiments. The bacteria showed preferential use of certain polysaccharides over others for growth, and this influenced their fermentation output qualitatively. These kinds of studies are essential in developing concepts of how the gut microbial community shares habitat resources, directly and indirectly, when presented with mixtures of polysaccharides that are found in human diets. The concepts are required in planning dietary interventions that might correct imbalances in the functioning of the human microbiota so as to support measures to reduce metabolic conditions such as obesity.

Development of a recombinase polymerase amplification assay for Vibrio parahaemolyticus detection with an internal amplification control.

A novel RPA-IAC assay using recombinase polymerase and an internal amplification control (IAC) for Vibrio parahaemolyticus detection was developed. Specific primers were designed based on the coding sequence for the toxR gene in V. parahaemolyticus. The recombinase polymerase amplification (RPA) reaction was conducted at a constant low temperature of 37 °C for 20 min. Assay specificity was validated by using 63 Vibrio strains and 10 non-Vibrio bacterial species. In addition, a competitive IAC was employed to avoid false-negative results, which co-amplified simultaneously with the target sequence. The sensitivity of the assay was determined as 3 × 103 CFU/mL, which is decidedly more sensitive than the established PCR method. This method was then used to test seafood samples that were collected from local markets. Seven out of 53 different raw seafoods were detected as V. parahaemolyticus-positive, which were consistent with those obtained using traditional culturing method and biochemical assay. This novel RPA-IAC assay provides a rapid, specific, sensitive, and more convenient detection method for V. parahaemolyticus.

Multiplex enrichment quantitative PCR (ME-qPCR): a high-throughput, highly sensitive detection method for GMO identification.

Among all of the high-throughput detection methods, PCR-based methodologies are regarded as the most cost-efficient and feasible methodologies compared with the next-generation sequencing or ChIP-based methods. However, the PCR-based methods can only achieve multiplex detection up to 15-plex due to limitations imposed by the multiplex primer interactions. The detection throughput cannot meet the demands of high-throughput detection, such as SNP or gene expression analysis. Therefore, in our study, we have developed a new high-throughput PCR-based detection method, multiplex enrichment quantitative PCR (ME-qPCR), which is a combination of qPCR and nested PCR. The GMO content detection results in our study showed that ME-qPCR could achieve high-throughput detection up to 26-plex. Compared to the original qPCR, the Ct values of ME-qPCR were lower for the same group, which showed that ME-qPCR sensitivity is higher than the original qPCR. The absolute limit of detection for ME-qPCR could achieve levels as low as a single copy of the plant genome. Moreover, the specificity results showed that no cross-amplification occurred for irrelevant GMO events. After evaluation of all of the parameters, a practical evaluation was performed with different foods. The more stable amplification results, compared to qPCR, showed that ME-qPCR was suitable for GMO detection in foods. In conclusion, ME-qPCR achieved sensitive, high-throughput GMO detection in complex substrates, such as crops or food samples. In the future, ME-qPCR-based GMO content identification may positively impact SNP analysis or multiplex gene expression of food or agricultural samples. Graphical abstract For the first-step amplification, four primers (A, B, C, and D) have been added into the reaction volume. In this manner, four kinds of amplicons have been generated. All of these four amplicons could be regarded as the target of second-step PCR. For the second-step amplification, three parallels have been taken for the final evaluation. After the second evaluation, the final amplification curves and melting curves have been achieved.

Critical Intermediates Reveal New Biosynthetic Events in the Enigmatic Colibactin Pathway.

Colibactin is a potent genotoxin that induces DNA double-strand breaks; it is produced by Escherichia coli strains harboring a pks+ island. However, the structure of this compound remains elusive. Here, using transformation-associated recombination (TAR) cloning to perform heterologous expression, we took advantage of the significantly increased yield of colibactin pathway-related compounds to determine and isolate a series of vital (pre)colibactin intermediates. The chemical structures of compounds 8, 10 and 11 were identified by NMR and MS(n) analyses. The new 1H-pyrrolo[3,4-c]pyridine-3,6(2H,5H)-dione- and thiazole-containing compound 10 provides new insights regarding the biosynthetic pathway to (pre)colibactin and establishes foundations for future investigation of the intriguing (pre)colibactin structures and its modes of action.

[Virulence-related genes of Vibrio alginolyticus and its virulence in mice].

OBJECTIVE: We determinated the virulence factors of Vibrio alginolyticus strains isolated from the environment by multiplex PCRs and animal experiments, in order to compare the differences between the highly virulent strain and attenuated virulent strain, and to explore the virulent mechanism of V. alginolyticus in mammals. METHODS: The virulence-related genes of V. alginolyticus were investigated by multiplex PCRs. Hemolysin and pathogenic proteins were detected using Kanagawa phenomenon tests and enzyme activity tests. In vivo pathogenetic tests of V. alginolyticus were done through orogastric and intraperitoneal Kunming mouse. RESULTS: Amylase and lecithinase activities were observed in 100% of the strains, whereas lipase and gelatinase activities were found in only 70% and urease activity was not detected. In Kanagawa phenomenon tests 60% of the strains gave positive results. The related virulence genes such as toxR, Collagenase, tlh, FlaA, ompW, AspA and fur were distributed among 10 strains of V. alginolyticus collected, with the exception of toxS, trh, tdh and UreR. Among those 10 strains, VA009 has shown a strong pathogenesis to the mouse, which caused fluid accumulation and led the mortality rate as high as 80% within 7 days by intraperitoneal infection. CONCLUSION: This study indicates that there is a great difference in pathogenicity among V. alginolyticus strains to mouse. The cell toxicity of V. alginolyticus made more contribution than extracellular secretion, while the extracellular secretion of V. parahaemolyticus played a major role in its toxicity. The virulence gene profiles were consistent between the highly virulent and attenuated virulent strains, indicating that V. alginolyticus might have a different virulence system and different pathogenic mechanism compared with V. parahaemolyticus.

Differential effects of pectin-based dietary fibre type and gut microbiota composition on in vitro fermentation outcomes.

Interactions between human gut microbiota and dietary fibres (DF) are influenced by the complexity and diversity of both individual microbiota and sources of DF. Based on 480 in vitro fermentations, a full factorial experiment was performed with six faecal inocula representing two enterotypes and three DF sources with nanometer, micrometer, and millimeter length-scales (apple pectin, apple cell walls and apple particles) at two concentrations. Increasing DF size reduced substrate disappearance and fermentation rates but not biomass growth. Concentrated DF enhanced butyrate production and lactate cross-feeding. Enterotype differentiated final microbial compositions but not biomass or fermentation metabolite profiles. Individual donor microbiota differences did not influence DF type or concentration effects but were manifested in the promotion of different functional microbes within each population with the capacity to degrade the DF substrates. Overall, consistent effects (independent of donor microbiota variation) of DF type and concentration on kinetics of substrate degradation, microbial biomass production, gas kinetics and metabolite profiles were found, which can form the basis for informed design of DF for desired rates/sites and consequences of gut fermentation. These results add further evidence to the concept that, despite variations between individuals, the human gut microbiota represents a community with conserved emergent properties.

A fructan-type garlic polysaccharide upregulates immune responses in macrophage cells and in immunosuppressive mice.

The anti-inflammatory effects of plant polysaccharides are well known. However, the stimulatory effects of polysaccharides under immunosuppressive conditions and their link with the polysaccharide structure is underexplored. In this work, the immune modulatory effects of a garlic polysaccharide (GP) are investigated via in vitro and vivo methods. It is observed that GP enhance the immune response of macrophages (RAW264.7) as indicated by the elevated levels of nitric oxide, TNF-α and IL-6. The observation that GP are able to stimulate the immune response in vitro was then explored with the use of an immunosuppressed mouse model. Surprisingly, GP exhibited dose-dependent up-regulatory impacts on the cyclophosphamide (CTX) suppressed levels of cytokines such as IFN-γ and IL-6 and immunoglobulins (e.g. IgA and IgG). The GP intervention reversed histopathological damage to the small intestine and spleen and increased fecal short-chain fatty acid levels. Moreover, GP modulates the gut microbiota dysbiosis by increasing the abundance of immunogenic bacteria such as g__norank_f__Erysipelotrichaceae, while inhibiting the over-abundance of g_Bacteroides. Functional predictions indicated that gut biomarkers of GP possessed the functions of glycoside hydrolase family 32 (GH32) and ß-fructofuranosidase. It is concluded that GP is a promising immunostimulant for immune-compromised individuals.

A novel antifungal peptide, SP1.2, from Rhodopseudomonas palustris against the rice blast pathogen.

BACKGROUND: Rice blast has a significant detrimental impact on rice yields, so developing efficient biological control technologies is an effective means for rice blast prevention and control. The GroEL protein has proven to be effective at preventing and managing the pathogenicity of rice blast. RESULTS: Here, we analyzed the amino acid sequence of the GroEL protein and synthesized the '60 kDa chaperonin signature' (350-373 amino acids) peptide SP1.2, which has potent antifungal activity. Notably, the SP1.2 peptide exhibited potent fungicidal activity against Magnaporthe oryzae, effectively inhibiting appressorium germination. Electron microscopy revealed that SP1.2 disrupted the fungal plasma membrane and bound to multiple bioactive phosphoinositides in vitro, triggering the production of reactive oxygen species. Furthermore, it also caused an increase in the acetylation of M. oryzae and induced autophagy in cells. The spray application of SP1.2 significantly reduced the number of disease spots caused by the fungal pathogen M. oryzae in rice, enhancing the defense response of rice plants. Field trials showed that the control effect was 64.59% after spraying SP1.2. CONCLUSION: Our study illustrates the antifungal activity of the structurally unique SP1.2 peptide against plant fungal pathogens and paves the way for the future development of this class of peptides as antifungal agents. © 2024 Society of Chemical Industry.

Edible Packaging as a Functional Carrier of Prebiotics, Probiotics, and Postbiotics to Boost Food Safety, Quality, and Shelf Life.

The safety limitations of chemical preservatives led to an increasing trend among industries and customers toward preservative-free foods; hence, the necessity has arisen for developing innovative, safe antimicrobial elements to prolong the shelf life. Beneficial microorganisms that are described as probiotics and also their metabolites are increasingly being considered as bioprotective agents. These microorganisms could be beneficial for extending food shelf-life and boosting human health. During distribution and storage (25 °C or 4 °C), they could contribute to suppressing unwanted microbes and then improving food safety and quality. Also, by tolerating the harsh conditions of gastrointestinal tract (low pH (~3), presence of bile salts, digestive enzymes, competition with other microbes, etc.), probiotics could exert several biological effects at the host. Besides inclusion in foods and supplements, probiotics and their functional metabolites could be delivered via edible packaging (EP). Recent studies have demonstrated the strong potential of pre/pro/post-biotic EP in food biopreservation. These packaging systems may show different potency of food biopreservation. Among others, postbiotics, as metabolic by-products of probiotics, have gained tremendous attention among researchers due to their unique properties like presenting a variety of antimicrobial activities, convenience in use in different industrial stages and commercialization, extended shelf life, and stability in a wide range of pH and temperature. In addition to antimicrobial activities, various bio-EP could differently influence physical or sensorial attributes of food commodities, impacting their acceptance by consumers. Hence, this study is aimed at presenting a comprehensive review of the application of bio-EP, not only by providing a protective barrier against physical damage but also by creating a controlled atmosphere to improve the health and shelf life of food.

Protective Effects of Mulberry (Morus atropurpurea Roxb.) Leaf Protein Hydrolysates and Their In Vitro Gastrointestinal Digests on AAPH-Induced Oxidative Stress in Human Erythrocytes.

Mulberry leaf protein hydrolysates (HMP), and their in vitro gastrointestinal digests (GHMP), have shown favorable chemical antioxidant activities. The aim of this study is to investigate the potential protective effects of HMP and GHMP against 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced oxidative stress in human erythrocytes. The inhibition rate of hemolysis, the reactive oxygen species (ROS) level, the concentration of malondialdehyde (MDA), the reduced glutathione (GSH) and oxidized glutathione (GSSH), and the enzymatic activities of total superoxide dismutase (SOD), catalase (CAT), and cellular glutathione peroxidase (GSH-Px) were evaluated as the biomarkers of oxidative status in human erythrocytes. The results showed that HMP and GHMP effectively inhibit the occurrence of erythrocyte hemolysis in the range of 0.025-1.0 mg/mL, and the inhibition rates of HMP and GHMP reached 92% and 90% at concentrations of 0.4 mg/mL and 1.0 mg/mL, respectively. HMP and GHMP reduced the AAPH-induced oxidative hemolysis damage via suppressing the generation of ROS by inhibiting the formation of MDA, maintaining the balance of GSH/GSSG, and preserving the activities of the antioxidant enzymes, including SOD, GSH-Px, and CAT. Our findings revealed that both HMP and GHMP could be used as natural antioxidants, and have the potential for further application in the development of functional foods.

Overexpression of ATP Synthase Subunit Beta (Atp2) Confers Enhanced Blast Disease Resistance in Transgenic Rice.

Previous research has shown that the pathogenicity and appressorium development of Magnaporthe oryzae can be inhibited by the ATP synthase subunit beta (Atp2) present in the photosynthetic bacterium Rhodopseudomonas palustris. In the present study, transgenic plants overexpressing the ATP2 gene were generated via genetic transformation in the Zhonghua11 (ZH11) genetic background. We compared the blast resistance and immune response of ATP2-overexpressing lines and wild-type plants. The expression of the Atp2 protein and the physiology, biochemistry, and growth traits of the mutant plants were also examined. The results showed that, compared with the wild-type plant ZH11, transgenic rice plants heterologously expressing ATP2 had no significant defects in agronomic traits, but the disease lesions caused by the rice blast fungus were significantly reduced. When infected by the rice blast fungus, the transgenic rice plants exhibited stronger antioxidant enzyme activity and a greater ratio of chlorophyll a to chlorophyll b. Furthermore, the immune response was triggered stronger in transgenic rice, especially the increase in reactive oxygen species (ROS), was more strongly triggered in plants. In summary, the expression of ATP2 as an antifungal protein in rice could improve the ability of rice to resist rice blast.

Characterization of Purified Mulberry Leaf Glycoprotein and Its Immunoregulatory Effect on Cyclophosphamide-Treated Mice.

Mulberry leaf protein is a potentially functional food component and health care agent with antioxidant and anti-inflammatory properties. However, its composition, immunoregulatory effects, and gut microbial regulatory effects are unclear. Herein, ultra-filtrated and gel-fractionated mulberry leaf protein (GUMP) was characterized. Its effects on cyclophosphamide-induced immunosuppressed mice were further investigated. The results indicated that GUMP is a glycoprotein mainly containing glucose, arabinose, and mannose with 9.23% total sugar content. Its secondary structure is mainly ß-sheet. LC-MS/MS analysis showed that GUMP closely matched with a 16.7 kDa mannose-binding lectin and a 52.7 kDa Rubisco's large subunit. GUMP intervention significantly improved serous TNF-α, IL-6, and IL-2 contents; increased serum immunoglobulins (IgA and IgG) levels; and reversed splenic damage prominently. Moreover, GUMP administration increased fecal shot-chain fatty acid concentration and up-regulated the relative abundance of Odoribacter, which was positively correlated with SCFAs and cytokine contents. Overall, GUMP alleviated immunosuppression through the integrated modulation of the gut microbiota and immune response. Therefore, GUMP could be a promising dietary supplement to help maintain gut health.

Proteomics Analysis Reveals the Molecular Mechanism of MoPer1 Regulating the Development and Pathogenicity of Magnaporthe oryzae.

Glycosylphosphatidylinositol (GPI) anchoring the protein GPI modification post-transcriptionally is commonly seen. In our previous study, MoPer1, a GPI anchoring essential factor, has a critical effect on Magnaporthe oryzae growth, pathogenicity, and conidiogenesis, but its molecular mechanism is not clear. Here, we extracted the glycoproteins from the ΔMoper1 mutant and wild-type Guy11 to analyze their differential levels by quantitative proteomic analysis of TMT markers. After background subtraction, a total of 431 proteins, with significant changes in expression, were successfully identified, and these differential proteins were involved in biological regulation, as well as cellular process and metabolic process, binding, catalytic activity, and other aspects. Moreover, we found that MoPer1 regulates the expression of 14 proteins involved in growth, development, and pathogenicity of M. oryzae. The above findings shed light on MoPer1's underlying mechanism in regulating growth, development, and pathogenicity of M. oryzae.

Anti-inflammatory effects and molecular mechanisms of bioactive small molecule garlic polysaccharide.

Although garlic polysaccharides have been found to possess anti-inflammatory activities, anti-inflammatory study on small molecule water-soluble garlic polysaccharide (WSGP) is few. In this study, a novel WSGP with a molecular weight of 1853 Da was isolated by DEAE-52 and Sephadex G-100 column and the chemical composition was identified by monosaccharide composition and methylation analysis. Furthermore, the antioxidant effects of WSGP and the potential molecular mechanisms on LPS-induced inflammatory responses in RAW264.7 macrophage cells were investigated. The results showed that WSGP has strong antioxidant activity, such as DPPH, hydroxyl, superoxide anion, ABTS radical scavenging capacity, Fe2+ chelating ability and reducing power. Meanwhile, WSGP could considerably suppress the manufacturing of NO and the mRNA and protein expression degrees of IL-6, TNF-α, and IL-1ß in LPS inspired RAW264.7 macrophages WSGP could significantly suppress the production of NO and the mRNA and protein expression levels of IL-1ß, IL-6, and TNF-α in LPS stimulated RAW264.7 macrophage cells (p < 0.05). In addition, the phosphorylated IκB-α, p65, and STAT3 proteins were significantly increased in LPS-induced macrophages, while this trend was significantly reversed by WSGP treatment in a concentration-dependent manner (p < 0.05). Consequently, WSGP supplementation might reduce LPS-induced inflammatory responses by suppressing proinflammatory cytokines and NF-κB and STAT3 pathway activation. The finding of this research would give scientific guidelines for the judicious use of small molecular garlic polysaccharide in anti-inflammatory treatments.

Effects of enzymatic hydrolysis on physicochemical property and antioxidant activity of mulberry (Morus atropurpurea Roxb.) leaf protein.

To improve the antioxidant efficiency of mulberry leaf protein (MLP), alcalase, protamex, papain, flavourzyme, neutrase, and trypsin were used to hydrolyze MLP. The yield of soluble peptides, secondary structures, molecular weight distributions, and antioxidant activities of MLP hydrolysates (MLPHs) were investigated. Results showed that the native MLP was rich in the fraction above 6.5 kDa and was mainly composed of ß-sheets, while MLPHs were abundant in the fractions of 0.3-0.6 kDa and 0.6-6.5 kDa and were mainly composed of disordered coils and ß-folds. Limited hydrolysis of MLP could lead to better antioxidant activity than extensive hydrolysis. After enzymatic hydrolysis, the content of total sugar and total phenol in MLP increased significantly. MLP hydrolysates prepared with neutrase, alcalase, and protamex were preferable to other enzymes. Meanwhile, an enzyme to substrate level of 1% and a hydrolysis time of 2 hr were the optimum conditions to obtain higher antioxidant hydrolysates using neutrase.

GroEL protein from the potential biocontrol agent Rhodopseudomonas palustris enhances resistance to rice blast disease.

BACKGROUND: GroEL, which is a chaperone, plays a key role in maintaining protein homeostasis and, among other functions, serves to prevent protein misfolding and aggregation. In addition, the GroEL protein also has a significant effect on enhancing plant resistance and inhibiting plant diseases. However, the function of the GroEL protein in the inhibition of rice blast remains unknown. RESULTS: Field experiment results show that photosynthetic bacteria PSB-06 have a good control effect on Magnaporthe oryzae. PSB-06 also can promote rice growth and enhance stress resistance. A GroEL protein which was separated and purified from photosynthetic bacteria had a significant antagonistic effect on appressorial formation and pathogenicity of Magnaporthe oryzae, meanwhile transcriptional analysis demonstrated that the GroEL protein could improve the expression of defense gene of rice. CONCLUSION: Our results show that the photosynthetic bacteria Rhodopseudomonas palustris significantly controls rice blast disease. Its action involves an extracellular GroEL protein, which inhibits appressoria formation, antagonizes the pathogenicity of Magnaporthe oryzae and promotes a host defense response. The research results provide evidence of the potential of this photosynthetic bacterium as a biocontrol agent at least for rice blast control. © 2021 Society of Chemical Industry.

Structural characterization and functional activity of an exopolysaccharide secreted by Rhodopseudomonas palustris GJ-22.

One water exopolysaccharide, designated G-EPS, was secreted by Rhodopseudomonas palustris GJ-22 culture media. The structure of G-EPS was characterized with HPGPC, GC-MS, methylation, 1D and 2D NMR, along with UV and FT-IR spectrum. The G-EPS molecular weight was 10.026 kilodalton, and is composed of D-mannose (92.8%) and d-glucose (7.2%). The purified G-EPS promoted plant growth and induced systemic resistance against TMV in Nicotiana benthamiana. These results suggested that G-EPS is an important active component of the bio-control capacity of GJ-22.

[Fermentation of two insoluble dietary fibers by colonic microflora in vitro].

OBJECTIVE: To investigate the rule of insoluble dietary fiber fermentation in intestinal tract. METHODS: Using destarched wheat bran and sugarcane residue as substrates for the fermentation of colonic microflora in vitro in anaerobic conditions. Samples were collected at 0, 4, 8, 12 and 24 h after fermentation, and the pH value, selective plate colony counts were measured and the content of SCFAs were detected with GC. RESULTS: After fermenting for pH 5.43. The change of colony counts of Bifidobacterium, Lactobacillus, Enterococci, Enterobacter, Bacteroides and total anaerobic bacterium was not significant in two media with different substrates at different fermentation periods. Both destarched wheat bran and sugarcane residue could be utilized by colon microbials to produce SCFAs, most of which was propionate at the amount of 0.58 mg/ml and 0.56 mg/ml respectively. During the fermentation process, lactic acid was accumulated and promptly consumed by colonic microflora. CONCLUSION: Insoluble dietary fiber could be fermented by intestinal microflora. The growth succession of colonic microflora might be varied during fermentation.

The effects of bioactive compounds from blueberry and blackcurrant powders on the inhibitory activities of oat bran pastes against α-amylase and α-glucosidase linked to type 2 diabetes.

The α-amylase and α-glucosidase inhibitory activities by extracts of oat bran, blueberry and blackcurrant powders, as well as oat bran pastes supplemented 25% of blueberry and blackcurrant powder, were studied by measuring their half inhibitory (IC50) concentrations. Addition of blueberry or blackcurrant powder into oat bran paste increased α-amylase and α-glucosidase inhibitory activities with a decrease in IC50 values. The main anthocyanidin content was measured by pH differential method and the potential inhibitory mechanisms of these extracts were also investigated by detailed inhibition kinetics and docking simulations. The results showed that: (1) cyanidin and delphinidin were the main anthocyanidin profiles in extracts; (2) only blackcurrant powder was a competitive inhibitor, while other extracts were all mixed-type inhibitors against α-amylase; (3) both blueberry- and blackcurrant-enriched pastes were competitive inhibitors, while other extracts were all mixed-type inhibitors towards α-glucosidase; (4) the α-amylase and α-glucosidase inhibitory activities by extracts were potentially driven by hydrogen bonding, cyanidin-3-glucoside and delphinidin-3-glucoside had stronger binding affinity compared to malvidin-3-glucoside and cyanidin-3-rutinside. This study suggested supplementary of blueberry and blackcurrant with oat bran might be a potential source of bioactive products for antidiabetic activity.