人体肠道菌群的试验模型的研究进展

肠道菌群与人体健康密切相关,肠内菌群可以参与人体发育、消化吸收、代谢等生理过程,因此,肠道菌群的平衡对我们的健康和疾病有着重要的影响。但是,肠道菌群数量及种类庞大,且与人体相互组成了非常复杂的生态系统,因此研究人体肠道菌群存在很多困难。文章综述了研究人体肠道菌群的体内和体外的具有代表性的试验模型方法,并概述了各模型方法的特点和问题,为完善和开发新的技术及方法提供基础与思路。     

Effectiveness of probiotics,prebiotics, and prebiotic‐like components in common functional foods

The bioactive ingredients in commonly consumed foods include, but are not limited to, prebiotics, prebiotic‐like components, probiotics, and postbiotics. The bioactive ingredients in functional foods have also been associated with beneficial effects on human health. For example, they aid in shaping of gut microflora and promotion of immunity. These functional components also contribute in preventing serious diseases such as cardiovascular malfunction and tumorigenesis. However, the specific mechanisms of these positive influences on human health are still under investigation. In this review, we aim to emphasize the major contents of probiotics, prebiotics, and prebiotic‐like components commonly found in consumable functional foods, and we present an overview of direct and indirect benefits they provide on human health. The major contributors are certain families of metabolites, specifically short‐chain fatty acids and polyunsaturated fatty acids produced by probiotics, and prebiotics, or prebiotic‐like components such as flavonoids, polyphenols, and vitamins that are found in functional foods. These functional ingredients in foods influence the gut microbiota by stimulating the growth of beneficial microbes and the production of beneficial metabolites that, in turn, have direct benefits to the host, while also providing protection from pathogens and maintaining a balanced gut ecosystem. The complex interactions that arise among functional food ingredients, human physiology, the gut microbiota, and their respective metabolic pathways have been found to minimize several factors that contribute to the incidence of chronic disease, such as inflammation oxidative stress.     

Probiotics,prebiotics, and microencapsulation: A review

The development of a suitable technology for the production of probiotics is a key research for industrial production, which should take into account the viability and the stability of the organisms involved. Microbial criteria, stress tolerance during processing, and storage of the product constitute the basis for the production of probiotics. Generally, the bacteria belonging to the genera Lactobacillus and Bifidobacterium have been used as probiotics. Based on their positive qualities, probiotic bacteria are widely used in the production of food. Interest in the incorporation of the probiotic bacteria into other products apart from dairy products has been increasing and represents a great challenge. The recognition of dose delivery systems for probiotic bacteria has also resulted in research efforts aimed at developing probiotic food outside the dairy sector. Producing probiotic juices has been considered more in the recent years, due to an increased concern in personal health of consumers. This review focuses on probiotics, prebiotics, and the microencapsulation of living cells.     

Diet Effects in Gut Microbiome and Obesity

The 100 trillion microbes in human gut coevolve with the host and exert significant influences on human health. The gut microbial composition presents dynamic changes correlated with various factors including host genotypes, age, and external environment. Effective manipulation of the gut microbiota through diets (both long‐term and short‐term diet patterns), probiotics and/or prebiotics, and antibiotics has been proved being potential to prevent from metabolic disorders such as obesity in many studies. The dietary regulation exerts influences on microbial metabolism and host immune functions through several pathways, of which may include selectively bacterial fermentation of nutrients, lower intestinal barrier function, overexpression of genes associated with disorders, and disruptions to both innate and adaptive immunity. Discoveries in the interrelationship between diet, intestinal microbiome, and body immune system provide us novel perceptions to the specific action mechanisms and will promote the development of therapeutic approaches for obesity.     

肠道微生物体外发酵模型研究进展及其在食品中的应用

随着分子微生态学,特别是高通量测序技术的快速发展,人们对肠道微生物的作用有了进一步认识。肠道不仅是消化吸收的场所,其微生物菌群现更被认为是一个高度特异化的\     

Evaluation of a gas in vitro system for predicting methane production in vivo

Methane production from ruminant livestock varies with the diet as a result of factors such as dry matter intake, diet composition, and digestibility. To estimate the effect of dietary composition and feed additives, CH₄ production can be measured in vitro as a first step because large numbers of samples can be incubated and analyzed at the same time. This study evaluated a recently developed in vitro method for prediction of in vivo CH₄ production by examining the relationship between predicted and observed CH₄ production values. A total of 49 different diets (observations), used in previous 13 in vivo studies, were selected to include diets varying in nutrient composition. Methane production was measured in all in vivo studies by respiration chambers or the GreenFeed system (C-Lock Inc., Rapid City, SD). Overall, the in vitro system predicted CH₄ production well (R² = 0.96), but the values obtained were slightly underestimated compared with observed in vivo values (mean 399 L/d compared with 418 L/d: root mean square prediction error = 51.6 L/d or 12.3% of observed mean). Further analysis of the effect on residuals showed no significant relationship between CH₄ production and most factors known to affect CH₄ production such as dry matter intake, digestibility, and dietary concentrations of fat and starch. However, some factors included in the model were not well predicted by the system, with residuals negatively related to neutral detergent fiber concentration and positively related to concentrate proportion. The in vitro system can thus be useful for screening diets and evaluation of feed additives as a first step that can be best interpreted when feeding cows at maintenance level.     

食品抗氧化评价体系及其选择使用

目前有许多食品抗氧化能力评价方法,但是对于特定的食品该选择何种抗氧化评价方法还不确定,为了解决这个问题,主要介绍不同抗氧化评价方法的机理及其特点,以及它们在食品抗氧化评价体系中的选择作用。从体外、体内两个方面对食品抗氧化评价特点进行具体地介绍,以达到对食品抗氧化性的全面分析。值得推荐的是从血浆脂质过氧化水平和氧化应激生物标志物对食品的抗氧化能力进行分析。     

黄精多糖体外消化特性及对Ⅱ型糖尿病小鼠肠道菌群的调节作用

本研究探讨黄精多糖体外消化特性、体外降血糖活性及对Ⅱ型糖尿病鼠肠道菌群的调节作用.以空白作对照,对黄精多糖进行体外消化,采用DNS法和凝胶色谱法测定黄精多糖在消化过程中还原糖含量和分子量的变化;对黄精多糖进行体外酵解实验,对酵解物进行16S rDNA分析,研究黄精多糖对糖尿病鼠肠道菌群的影响.研究结果表明,在胃部消化模...     

Intake of Pro- and/or Prebiotics as a Promising Approach for Prevention and Treatment of Colorectal Cancer

Colorectal cancer (CRC) is the third most common type of cancer, posing a serious threat to human life. It is widely believed that dietary factors may be crucial modifiers of CRC risk, with pro-and/or prebiotics being especially promising. In this review, a synthesis of CRC prevention and treatment of strategies relying on usage of pro- and/or prebiotics supplements is given, as well as discuss mechanisms underlying the contribution of pro-and/or prebiotics to the suppression of colonic carcinogenesis. Furthermore, a framework for personalizing such supplements according to the composition of an individual's gut microbiome is suggested. Various factors including diversity of one's intestinal microflora, integrity of their intestinal barrier, and the presence of mutagenic/carcinogenic/genotoxic and beneficial compounds are known to have a prominent influence on the development of CRC; thus, clarifying the role of pro- and/or prebiotics will yield valuable insight toward optimizing interventions for enhanced patient outcomes in the future.     

Influence of Intestinal Microbiota on the Catabolism of Flavonoids in Mice

Although in vitro studies have shown that flavonoids are metabolized into phenolic acids by the gut microbiota, the biotransformation of flavonoids by intestinal microbiota is seldom studied in vivo. In this study, we investigated the impact of the gut microbiota on the biotransformation of 3 subclasses of flavonoids (flavonols, flavones, and flavanones). The ability of intestinal microbiota to convert flavonoids was confirmed with an in vitro fermentation model using mouse gut microflora. Simultaneously, purified flavonoids were administered to control and antibiotic‐treated mice by gavage, and the metabolism of these flavonoids was evaluated. p‐Hydroxyphenylacetic acid, protocatechuic acid, p‐hydroxybenzoic acid, vanillic acid, hydrocaffeic acid, coumaric acid, and 3‐(4‐hydroxyphenyl)propionic acid were detected in the serum samples from the control mice after flavonoid consumption. The serum flavonoid concentrations were similar in both groups, whereas the phenolic metabolite concentrations were lower in the antibiotic‐treated mice than in the control mice. We detected markedly higher flavonoids excretion in the feces and urine of the antibiotic‐treated mice compared to the controls. Moreover, phenolic metabolites were upregulated in the control mice. These results suggest that the intestinal microbiota are not necessary for the absorption of flavonoids, but are required for their transformation.     

Gut microbiota modulation and immune boosting properties of prebiotic dragon fruit oligosaccharides

This is the first report of the evaluation of suitability for consumption of dragon fruit oligosaccharide (DFO) and its efficacy on gut microbiota modulation and in boosting the gut immune response in rats. The DFO produced significantly increased faecal bifidobacteria and lactobacilli but decreased bacteroides and clostridia. The DFO also showed immune-response boosting properties by significantly increasing the plasma immunoglobulin A and G concentrations. In addition, it was confirmed by blood chemistry analysis and histology of the colon of the rats that DFO is suitable for the consumption. These results suggest that DFO is a potentially novel source of prebiotic ingredients with probiotic-stimulation and immune boosting properties.     

In vitro activity on human gut bacteria of murta leaf extracts (Ugni molinae turcz.), a native plant from southern Chile

Despite the fact that murta infusions have been used to treat gut/urinary infections by native Chileans for centuries, the mechanisms promoting such effects still remain unclear. As a first attempt to unravel these mechanisms, human fecal samples were incubated in a medium containing water extract of murta leaves (ML) and the growth of different bacterial groups was evaluated. Control incubations were made in media containing fructooligosaccharides (FOS) and glucose as a carbon source. Phenolic compounds in the ML extract, likely promoters of bioactivity, were identified by HPLC-DAD-MS(n) . Concentrations (log(10) CFU/mL) of bifidobacteria and lactobacilli in media containing the extract and FOS were 7.33 ± 0.05/4.95 ± 0.20 and 6.44 ± 0.22/6.05 ± 0.06, respectively. Clostridia, anaerobes and Enterobacteriaceae grew to a similar extent in media containing murta extract and FOS. In vitro tests (disk diffusion) showed that Gram-positive (Bacillus and Paenibacillaceae) and Gram-negative (Enterobacteriaceae) bacteria isolated from fecal samples were sensitive to both water and 50/50 ethanol/water extracts of ML (28.4 μg gallic acid equivalents). At this concentration, the antimicrobial activity of ML extracts was significantly (P < 0.05) lower than that of penicillin (10 U), whereas the difference between activity of ML extracts and gentamicine (10 μg) was no significant (P > 0.05). No evidence of dependency between the antimicrobial activity of ML extracts and the enzymatic capability of the sensitive strains was found.     

OPO乳脂粉对肠道微生物体外发酵的影响

为进一步明晰1,3-二油酸-2-棕榈酸甘油三酯（1,3-dioleoyl-2-palmitoyl triglyceride,OPO）乳脂粉的营养机制,扩大OPO的食用范围,以健康大学生粪便为菌源,采用体外厌氧发酵模式,结合传统培养技术和气相色谱法,研究不同含量OPO乳脂粉24 h体外发酵过程中pH值、短链脂肪酸的变化,并分析肠道微生物,计算益生元指数和B/E（Bifidobacterium/Enterobacter）值。结果显示：OPO乳脂粉的添加,能迅速降低发酵液的pH值,下降幅度与OPO含量呈正比;能大幅度增加总短链脂肪酸含量,其中,乙酸和丁酸含量增加明显;能显著促进双歧杆菌和乳酸杆菌的生长,抑制肠杆菌和拟杆菌的生长,提高益生元指数和B/E值,其中OPO含量50 g/kg组在24 h发酵过程中益生元指数最高,在发酵12 h内双歧杆菌增加数量、B/E值均与OPO含量呈正比。因此,综合考虑益生效率,推荐添加组为50 g/kg组。     

电子烟基因毒性评价方法概述

为了解电子烟的基因毒性及其评价方法,按照受试对象分类进行了综述。其中以细菌为受试对象的试验方法有细菌回复突变试验和DNA损伤分析等;以离体细胞为受试对象的试验方法有微核试验、DNA双链断裂试验、RNA转录测序试验、定向基因检测分析和Bhas细胞转化试验等;以模式动物为受试对象的试验方法有长期吸入毒性试验和生殖发育毒性试验等;以人体为受试对象的主要是临床试验和流行病学调查研究等。由于受试对象和试验方法的差异性,导致电子烟基因毒性结果的可信度和可比性较差,因此建议在评价电子烟基因毒性的过程中,应至少考虑细菌、离体细胞、模式动物和临床试验等4个层次的受试对象,通过回复突变试验、微核试验、长期吸入毒性试验和临床试验等多种试验方法获得多个基因毒性的试验终点,科学、客观和全面地综合评价电子烟的基因毒性。     

Progress in microencapsulation of probiotics: A review

The potential health benefits of probiotics may not be realized because of the substantial reduction in their viability during food storage and gastrointestinal transit. Microencapsulation can be used to enhance the resistance of probiotics to unfavorable conditions. A range of oral delivery systems has been developed to increase the level of probiotics reaching the colon including embedding and coating systems. This review introduces emerging strategies for the microencapsulation of probiotics and highlights the key mechanisms of their stress–tolerance properties. Recent in vitro and in vivo models for evaluation of the efficiency of probiotic delivery systems are also reviewed. Encapsulation technologies are required to maintain the viability of probiotics during storage and within the human gut so as to increase their ability to colonize the colon. These technologies work by protecting the probiotics from harsh environmental conditions, as well as increasing their mucoadhesive properties. Typically, the probiotics are either embedded inside or coated with food‐grade materials such as biopolymers or lipids. In some cases, additional components may be coencapsulated to enhance their viability such as nutrients or protective agents. The importance of having suitable in vitro and in vivo models to evaluate the efficiency of probiotic delivery systems is also emphasized.     

高链玉米淀粉-不饱和脂肪酸复合物的体外大肠发酵特性及其对肠道菌群的影响规律

该研究以高直链玉米淀粉（High-Amylose Maize Starch,HAMS）与四种饱和度不同的脂肪酸为原料,制备淀粉-不饱和脂肪酸复合物,研究不同复合物体外大肠发酵特性及菌群调控的影响。结果表明,随着脂肪酸不饱和度的增加,除淀粉-油酸复合物（34.87%）外,形成的复合物V型结晶越少（30.42%~32.93%）。淀粉-不饱和脂肪酸复合物在整个发酵过程中发酵速率无显著性差异（p>0.05）,最终产气量基本一致（13.8~14.2 mL）。淀粉-不饱和脂肪酸复合物产丁酸浓度（14.83~17.91 mmol/L）低于HAMS （22.42 mmol/L）,但产较多乙酸（60.25~63.73 mmol/L）和丙酸（21.22~24.81 mmol/L）。淀粉-不饱和脂肪酸复合物均能显著促进Prevotella的相对丰度,这与其较高的丙酸产量有关。综上,淀粉-不饱和脂肪酸复合物大肠发酵特性受脂肪酸饱和度的影响较小,主要与淀粉-脂质复合物自身结构有关,复合物中脂肪酸的饱和度对高链玉米淀粉-不饱和脂肪酸复合物菌群结构具有一定影响。     

The effect of prebiotics on adherence of probiotics

Prebiotics are generally considered to promote the function or viability of probiotics via their fermentation, but their effect on the adherence of probiotics is still unclear. In this study, we examined the effect of 4 commercially available prebiotics [Orafti GR, Orafti P95, and Orafti Synergy (Beneo GmbH, Mannheim, Germany), and Vivinal (Friesland Foods Domo, Amersfoort, the Netherlands)] and 3 simple saccharides (glucose, galactose, and lactose) on the adherence of 5 probiotic type strains, 2 lactococci starter cultures, and 5 potential dairy probiotic strains from the Culture Collection of Dairy Microorganisms (Tábor, Czech Republic). Adherence was tested in microtiter plates on the following types of substrate: polystyrene alone and polystyrene coated with either porcine mucus or cocultures of the human colon cell lines Caco2 and HT29-MXT (1:9 ratio of HT29-MXT:Caco2). Adherence was evaluated as a change in fluorescence in the well of a microtiter plate. The most commonly observed effect (with a few exceptions) of prebiotics was decreased adherence of the tested strains observed on all types of substrate. The tested saccharides, which are part of the residual compounds of the used prebiotics, had a very similar effect—eliciting a decrease in adherence ability in the majority of the probiotic strains.