β-果糖基转移酶的性质研究

目的研究低聚果糖产生菌黑曲霉 (Aspergillusniger)SIPI 6 0 2来源的 β 果糖基转移酶 (β FT)的性质。 方法经典的酶学研究方法。结果 β FT催化蔗糖转化成蔗果三糖的Km和Vmax分别为 2 6 8.37g L和 2 .37g (min·L) ;将蔗果三糖转化成蔗果四糖的Km和Vmax分别为 173.0 8g L和 0 .10g (min·L)。葡萄糖是 β FT的竞争性抑制剂 ,其Ki=2 4 5 .2 3g L。β FT反应的最适pH为 4 .5～ 6 .0 ,最适温度为 5 5℃。β FT在中性条件、5 0℃以下稳定性良好。β FT转化蔗糖生成低聚果糖的反应进程实验表明 ,高浓度的底物有利于提高反应速度和转化率 ,并且产物中果糖浓度较低浓度底物中低。结论黑曲霉SIPI 6 0 2来源的 β FT适合用于工业化生产低聚果糖     

Identification and Determination of Fructooligosaccharides in Snow Chrysanthemum (Coreopsis tinctoria Nutt.)

Objective: Small molecules in snow chrysanthemum such as flavonoids, phenolic compounds and amino acids have been extensively investigated. No study to date has focused on water-soluble oligosaccharides. The objective of this study is identification and determination of water-soluble oligosaccharides in snow chrysanthemum. Methods: The oligosaccharides in snow chrysanthemum were identified by high performance thin layer chromatography (HPTLC), liquid chromatography-massspectrometry (LC-MS) combined MS library and methylation analysis for the first time. Subsequently the oligosaccharides were determined by high performance liquid chromatography with a charged aerosol detector (HPLC-CAD). Results: The oligosaccharides in snow chrysanthemum were identified as inulin-type fructooligosaccharides (FOS). The yield of FOS (DP3~DP13) in the first extraction was over 97.6%. The RSDs of repeatability in three sample amount levels (0.08 g, 0.1 g, 0.12 g) are lower than 4.8% and the RSDs of stability are less than 3.5%. The recoveries of FOS (DP3~13) were ranging from 96.9% to 105.6%. The contents of FOS (DP3~DP13) in flowers of snow chrysanthemum from different regions of China were greatly variant. Conclusion: This is the first time to identify and quantify FOS in snow chrysanthemum which is helpful for its performance in the in the fields of biomedical, agriculture and functional food industry as well as development of the quality control methods. In addition, the identification approach developed in this work can also be used for screening potential natural sources containing FOS.     

Effect of probiotics on respiratory,gastrointestinal and nutritional outcomes in patients with cystic fibrosis: A systematic review

Background

An increasing body of research investigating the use of probiotics to improve health outcomes in patients with cystic fibrosis (CF) prompted the need to systematically assess and summarise the relevant literature.

In vitro fermentation characteristics of a mixture of Raftilose and guar gum by human faecal bacteria

Summary Background The therapeutic effects of indigestible carbohydrates in the human colon are well known. Most fermentation studies have examined only single carbohydrates. Considering the idiosyncratic actions of individual carbohydrates and the dose required, it is unlikely that any one carbohydrate will provide ideal physiological actions without having some undesirable effects. Little is known of how mixing non–digestible carbohydrates affects their fermentation. This necessitates fermentation studies using different carbohydrates in mixtures. Aim of the study The aim of this study was to test the effect of mixing Raftilose™ (R) and guar gum (G) on short chain fatty acid (SCFA) production in in vitro cultures of human faecal bacteria. Method The fermentation of the individual carbohydrates (10 mg/ml) was compared with that of a 50:50 mixture in anaerobic in vitro cultures of human faeces. Results Cultures of R/G mixtures produced significantly more n–butyrate than 100 mg G alone at 8 and 24 hours (p < 0.02). There was no significant difference in the production of n–butyrate between cultures of 100 mg R and the R/G mixture at 8 and 24 hours. R (100 mg) produced a propionic/butyric (p/b) acid ratio of 1.18 compared with 3.88 for 100 mg G, whereas R/G mixture produced a p/b ratio of 2.01. Conclusion The fermentation of R/G mixture was different compared with 100 mg of R or G alone. There was no loss of n–butyrate in the culture containing R/G (50 mg of each) mixture compared with the 100 mg R culture.     

离子交换树脂固定果糖转移酶

超声波破碎黑曲霉细胞提取游离果糖转移酶,然后选择D201大孔阴离子交换树脂为载体,通过先吸附后交联的方法固定果糖转移酶.优化的固定化条件:加酶量为每克湿树脂400U,吸附pH值为5.0～5.5,吸附温度为30℃,吸附时间为8h,交联剂戊二醛(终)质量浓度为0.01～0.05g/dL,交联时间为8h,交联温度为1～4℃.固定化酶活最高回收率为30.2%.     

Antioxidant Vitamins and Prebiotic FOS and XOS Differentially Shift Microbiota Composition and Function and Improve Intestinal Epithelial Barrier In Vitro

Human gut microbiota (HGM) play a significant role in health and disease. Dietary components, including fiber, fat, proteins and micronutrients, can modulate HGM. Much research has been performed on conventional prebiotics such as fructooligosaccharides (FOS) and galactooligosaccharides (GOS), however, novel prebiotics or micronutrients still require further validation. We assessed the effect of FOS, xylooligosaccharides (XOS) and a mixture of an antioxidant vitamin blend (AOB) on gut microbiota composition and activity, and intestinal barrier in vitro. We used batch fermentations and tested the short-term effect of different products on microbial activity in six donors. Next, fecal inocula from two donors were used to inoculate the simulator of the human microbial ecosystem (SHIME) and after long-term exposure of FOS, XOS and AOB, microbial activity (short- and branched-chain fatty acids and lactate) and HGM composition were evaluated. Finally, in vitro assessment of intestinal barrier was performed in a Transwell setup of differentiated Caco-2 and HT29-MTX-E12 cells exposed to fermentation supernatants. Despite some donor-dependent differences, all three tested products showed beneficial modulatory effects on microbial activity represented by an increase in lactate and SCFA levels (acetate, butyrate and to a lesser extent also propionate), while decreasing proteolytic markers. Bifidogenic effect of XOS was consistent, while AOB supplementation appears to exert a specific impact on reducing F. nucleatum and increasing butyrate-producing B. wexlerae. Functional and compositional microbial changes were translated to an in vitro host response by increases of the intestinal barrier integrity by all the products and a decrease of the redox potential by AOB supplementation.     

Development of a Mixed Beverage with the Addition of Prebiotics: Consumer Acceptance and Focus Groups

ABSTRACT

A innovate cashew-based mixed fruit beverage incorporated with prebiotics was elaborated consumer acceptance and expectation were applied to evaluate the product; a possible package for the beverage was survey, using focal group, in order to verify the influence of this on consumer buying intention. Acceptance analyzes were performed in three sessions, along with the focus group technique. The beverage showed the greatest acceptance when mixed with mango or guava. The package chosen as most adequate for the 245 mL single dose had a layout with simple, practical colors, and for the larger volumes the packages was chosen made of glass and the Tetra Pak system, with an open-shut mechanism and 1 L volume. The format and type of package had an impact on the choice, but the decision to buy depended on the price of the final product, and their acceptance.     

Quantification of fructans,galacto‐oligosacharides and other short‐chain carbohydrates in processed grains and cereals

Background: Wholegrain grains and cereals contain a wide range of potentially protective factors that are relevant to gastrointestinal health. The prebiotics best studied are fructans [fructooligosaccharides (FOS), inulin] and galactooligosaccharides (GOS). These and other short‐chain carbohydrates can also be poorly absorbed in the small intestine (named fermentable oligo‐, di‐ and monosaccharides and polyols; FODMAPs) and may have important implications for the health of the gut. Methods: In the present study, FODMAPs, including fructose in excess of glucose, FOS (nystose, kestose), GOS (raffinose, stachyose) and sugar polyols (sorbitol, mannitol), were quantified using high‐performance liquid chromatography with an evaporative light scattering detector. Total fructan was quantified using an enzymic hydrolysis method. Results: Fifty‐five commonly consumed grains, breakfast cereals, breads, pulses and biscuits were analysed. Total fructan were the most common short‐chain carbohydrate present in cereal grain products and ranged (g per portion as eaten) from 1.12 g in couscous to 0 g in rice; 0.6 g in dark rye bread to 0.07 g in spelt bread; 0.96 g in wheat‐free muesli to 0.11 g in oats; and 0.81 g in muesli fruit bar to 0.05 g in potato chips. Raffinose and stachyose were most common in pulses. Conclusions: Composition tables including FODMAPs and prebiotics (FOS and GOS) that are naturally present in food will greatly assist research aimed at understanding their physiological role in the gut.     

Dietary fructooligosaccharides up-regulate immunoglobulin A response and polymeric immunoglobulin receptor expression in intestines of infant mice

We examined whether or not dietary fructooligosaccharides (FOS) in infancy can have a beneficial effect on the mucosal immune system. Newborn BALB/c mice, accompanied by their dams until 21 days of age, were fed either a control diet based on casein [FOS- diet group] or a FOS- diet supplemented with 5% (w/w) FOS [FOS+ diet group]. Total IgA levels in tissue extracts from the intestines of mice in the FOS+ diet group at 38 days of age were about twofold higher (P < 0.05) than those in the FOS- diet group in the jejunum, ileum and colon. Ileal and colonic polymeric immunoglobulin receptor (pIgR) expression in the FOS+ diet group at 36 days of age was 1.5-fold higher than in the FOS- diet group (P < 0.05). Consistent with these results, the ileal IgA secretion rate of the FOS+ diet group at 37 days of age was twofold higher than that of the FOS- diet group (P < 0.05). Moreover, the percentage of B220(+)IgA+ cells in Peyer's patches (PP) was significantly higher in the FOS+ diet group than in the FOS- diet group (6.2%versus 4.3%, P < 0.05), suggesting that isotype switching from IgM to IgA in PP B cells might be enhanced in vivo. Taken together, our findings suggest that dietary FOS increases the intestinal IgA response and pIgR expression in the small intestine as well as the colon in infant mice.