复合低聚糖对短双歧杆菌增殖作用的初步研究

以低聚异麦芽糖、低聚木糖及低聚异麦芽糖/低聚木糖(7:3)为碳源,在厌氧条件下增殖短双歧杆菌。研究表明,低聚异麦芽糖、低聚木糖及复合低聚糖对短双歧杆菌有明显的增殖作用,其最佳增殖浓度均为1.0%,且复合低聚糖之间没有协同效应。     

Preparation of Bifidobacterium breve encapsulated in low methoxyl pectin beads and its effects on yogurt quality

Yogurt is a popular product worldwide partly because of the health-promoting effects of the probiotics that it contains. Probiotics with high survivability constitute a promising direction for fortified yogurt products. This study aimed to prepare Bifidobacterium breve–loaded yogurt with the bacteria surviving transit to the lower part of small intestine or colon. Bifidobacterium breve beads were prepared through an ion-crosslinking method using low methoxyl pectin as the encapsulating material. Features such as encapsulation efficiency and stability during storage and passage through the simulated gastrointestinal tract were studied in vitro. A commercial starter was used for yogurt fermentation, and B. breve with or without encapsulation was added as a probiotic supplement with the starter or 3 to 4 h after fermentation. The effects of B. breve beads on yogurt characteristics were evaluated after different fermentation processes: BC, milk fermented with marketed yogurt starter; UBFF, unencapsulated B. breve added to fresh milk and then fermented; EBFF, encapsulated B. breve added to fresh milk and then fermented; UBAF, unencapsulated B. breve added after fermentation with the starter; and EBAF, encapsulated B. breve beads added 3 to 4 h after fermentation with the starter. Evaluation was based on texture, electronic nose, and electronic tongue analyses. The particle size analysis of B. breve beads showed that they were uniform, mostly spherical, 1 to 1.5 mm in diameter with encapsulating efficiency higher than 99%. Following treatment with the simulated gastrointestinal tract conditions, the number of B. breve decreased by 1.76 and 4.82 log cfu/g for B. breve beads and unencapsulated B. breve, respectively. The EBAF group showed the lowest viscosity (2,235.67 cP) at d 0, and the lower postfermentation degree was reflected by the slow increase in yogurt viscosity. All groups kept a relatively stable pH during storage. The cohesiveness values of the EBAF and UBAF groups were significantly higher than those of the other groups. The trends in texture changes within the BC, UBFF, and EBFF groups were similar, and the UBAF and EBAF groups showed similar trends. In conclusion, B. breve beads showed good stability in vitro and improved yogurt characteristics by increasing the survival rate of the encapsulated cells. Good compatibility of low methoxyl pectin beads with yogurt was also observed.     

Improving the storage stability of Bifidobacterium breve in low pH fruit juice

Bifidobacterial food applications are limited since bifidobacteria are sensitive to e.g. acidic conditions prevalent in many food matrices. The aim of the present study was to investigate whether a low pH selection step alone or combined to UV mutagenesis could improve the viability of an acid sensitive Bifidobacterium strain, B. breve 99, in low pH food matrices. Furthermore, the potential of carriers and an oat fibre preparation to further improve the stability was studied. The best performing low pH tolerant variants in the present study were generated by UV-mutagenesis with 70-700 μJ/cm² followed by incubation in growth medium at pH 4.5. The most promising variants regarding the low pH tolerance showed, in repeated tests with cells grown without pH control, about one Log-value better survival in pH 3.8 fruit juice after one week storage at 4 °C compared to wild-type B. breve 99. Cells grown with pH control, PDX formulated and then frozen showed poorer viability in low pH fruit juice than cells grown with no pH control. For frozen concentrates pH 3.8 was too stressful and no or small differences between the variants and the wild-type strain were seen. The differences detected at pH 3.8 with the cells grown without pH control were also seen with the frozen concentrates at pH 4.5. Some improvement in the stability could be achieved by using a combination of trehalose, vitamin C and PDX as a freezing carrier material, whereas a significant improvement in the stability was seen when oat fibre was added into the fruit juice together with the frozen cells. Due to the initial very poor fruit juice tolerance of B. breve 99 the obtained improvement in the stability was not enough for commercial applications. However, the same methods could be applied to initially better performing strains to further improve their stability in the fruit juice.     

Safety and intestinal microbiota modulation by the exopolysaccharide-producing strains Bifidobacterium animalis IPLA R1 and Bifidobacterium longum IPLA E44 orally administered to Wistar rats

Bifidobacterium animalis subsp. lactis IPLA R1 and Bifidobacterium longum IPLA E44 strains were tested for their safety and ability to modulate the intestinal microbiota in vivo. Chemically simulated gastrointestinal digestion showed considerably lower survival of E44 than R1 strain, the first microorganism also being more sensitive to refrigerated storage in 10% skimmed milk at 4 °C. Harmful glycosidic activities were absent, or at low levels, in the strains R1 and E44. Both strains were sensitive to most antibiotics and resistant to aminoglycosides, a common feature in bifidobacteria. Similar to several other bifidobacteria strains, B. animalis subsp. lactis IPLA R1 displayed a moderate resistance against tetracycline which correlated with the presence of tet(W) gene in its genome. The general parameters indicating well-being status, as well as translocation to different organs and histological examination of the gut tissues, revealed no changes induced by the administration of bifidobacteria to rats. Twelve-week-old male Wistar rats were distributed into three groups, eight rats in each. Two groups were administered daily over 10⁸ cfu of the corresponding strain suspended in 10% skimmed milk for 24 days, whereas rats in the placebo group received skimmed milk without microorganisms added. The microbiota and short chain fatty acids (SCFA) were monitored in faeces at different time points during treatment and in caecum content at the end of the assay. Quantitative PCR (qPCR) showed that faecal and caecal Bifidobacterium levels were higher in bifidobacteria-fed rats than in the placebo rats at the end of the intervention, whereas total anaerobic plate counts did not show significant differences. Quantification of B. animalis and B. longum by qPCR showed that, independent of the microorganism administered, treatment with bifidobacteria resulted in higher levels of B. animalis in the caecum. PCR-DGGE analysis of microbial populations revealed a higher diversity of bands in caecum content of rats fed B. animalis IPLA R1 than in the placebo group and rats fed B. longum IPLA E44. Remarkably, although no variations in the proportion of acetate, propionate and butyrate were found, at the end of the assay the total SCFA concentration in the faeces of rats fed bifidobacteria was significantly higher and those in caecum content significantly lower, than that of the placebo group. This suggests a displacement of the SCFA production to parts of the colon beyond the caecum in rats receiving bifidobacteria. Therefore, the oral administration of B. animalis IPLA R1 and B. longum E44 can be considered safe, these microorganisms having the ability to modulate the intestinal microbiota of rats by influencing SCFA and the bifidobacterial population levels.     

Calcium absorption in the small intestine in rats during hypokinesia

The method of averted and non-averted segments was used to assess calcium absorption in the small intestine of adult and young rats with hypokinesia. A certain decrease in the active (by 13.8%) and more manifest diminution of the total (by 26.3%) calcium transport was established in adult rats after 4 weeks of hypokinesia. In young rats a significant lowering of the active calcium transport was already noted after 1 week of hypokinesia, however, age-dependent shifts in the process were more significant than those induced by hypokinesia. Changes in the calcium-regulating hormones are considered as a possible cause of decreased calcium absorption in the intestine in relation to hypokinesia and age.     

Immunogenicity of Bifidobacterium breve and change in antibody production in Peyer's patches after oral administration

Immunogenicity in the intestine of Bifidobacterium breve, included in fermented milk, was compared with that of Bacteroides thetaiotaomicron, also predominant in human intestine. In vivo, serum antibody to B. breve was detected first in mice fed the organism for 33 d; antibody decreased in mice fed these for more than 33 d. Serum antibody to Bact. thetaiotaomicron was detected in mice fed the organism for 7 d and was maintained at the same level in mice fed these for more than 7 d. From in vitro tests, the optimal doses of B. breve and Bact. thetaiotaomicron to induce antibody production by Peyer's patch cells, intestinal lymphoid tissue cells, were 5 x 10(8) and 5 x 10(7) bacteria/ml, respectively. Therefore, it was suggested that immunogenicity of B. breve is weaker than that of Bact. thetaiotaomicron. Furthermore, the change of antibody production to the organism by Peyer's patch cells in the mice administered B. breve orally was tested by the Peyer's patch cell culture method. Antibody production against B. breve by Peyer's patch cells in mice given B. breve for 25 and for 33 d increased and decreased, respectively, in comparison with the control. These results suggest that when serum antibody to B. breve increases significantly, anti-B. breve antibody production by Peyer's patch cells is suppressed, and thereafter, serum antibody to B. breve decrease and is not detected. These findings favor the view that serum antibody production to B. breve is regulated in Peyer's patches.     

Digestive function of the small intestine and pancreas in rats on artificial feeding

Full-value diets of similar composition were given to male rats weighing 207-230 g, by intravenous (group 1) or intragastric (group 2) routes. The proportion of amino acids, fats and carbohydrates was 9.9:15.7:74.4 (with regard to their calorific value). The diet calorific value comprised 60.6 kcal/rat/day. An average mass increase in group 1 was 2.44 +/- 0.14 g/day, in group 2 - 1.75 +/- 0.11 g/day. The protein content and activities of alpha- and gamma-amylase, invertase, maltase, and glycil-L-leucine dipeptidase were assayed in the intestinal mucosa of the proximal portion of the small intestine in group 1 rats, while a decreased alpha-amylase activity in the distal portion of the small intestine was recorded in the animals of group 2. The mass of the pancreas in the rats of group 1 and 2 was authentically lower than in the control rats which received oral feeding with natural foods. The lowest mass of the pancreas was observed in the rats of group 1. Specific activity of trypsin, lipase and RNase in the pancreatic tissues of rats in groups 1 and 2 was similar. The results of the study have evidenced a lowered function of the digestive system under conditions of artificial feeding, especially in case of intravenous nutrition.     

Changes in the mucosa of the small intestine in white rats in the process of digestion

Morphological and morphometric studies of the small intestine of albino rats have shown that its villi undergo cyclic changes. These changes involve the death, growth and maturation of the villi. Digestion intensifies proliferative processes in the small intestinal mucosa. The data obtained support the conception that the death of the villi is a morphological expression of secretion (excretion) and absorption in the small intestine.     

Growth promotion of Bifidobacterium and Lactobacillus species by proteinaceous hydrolysates derived from poultry processing leftovers

Bacterial growth media represent a high cost in industrial applications, and for this reason, it is economically important to find less expensive supplements to replace the traditional ones. In the present work, peptide hydrolysates obtained from poultry meat and bone residues (functional animal protein [FAP]) and from feathers (functional feather protein [FFP]) were studied to determine their ability for the production of microbial biomass with improved viability. The results obtained were compared with those obtained with other supplement nutritive compounds used in fermentation growth media. The molecular composition of the hydrolysates in terms of total and soluble nitrogen, molecular weight distribution, total and free amino acids, was determined. The growth and cellular state of Bifidobacterium and Lactobacillus strains were studied by turbidimetric measurements and direct count by fluorescence microscopy. Overall, this study suggested that by‐products from poultry industry provide a good alternative to substitute expensive supplements for growth of Lactobacillus and Bifidobacterium with a high level of viability.     

Nitric oxide (NO) production in mammalian non-tumorigenic epithelial cells of the small intestine and macrophages induced by individual strains of lactobacilli and bifidobacteria

Nitric oxide (NO) affects multiple gastrointestinal functions, including mucosal inflammation and antimicrobial activity. The aim of this study was to screen the ability of probiotic bacteria to stimulate NO production in porcine intestinal epithelial cells and macrophages in the presence and absence of interferon gamma (INF-γ). Production of NO in intestinal epithelium was stimulated by individual strains of lactobacilli without INF-γ priming. While none of the tested bifidobacteria were capable of inducing NO production, most constitutively secreted NO. Most tested strains induced a significant increase in NO production compared with the control cells in the macrophage cell line 3D4/21. Results support the protective role of the individual strains of the genera Lactobacillus and Bifidobacterium and may lead to new approaches for manipulating and regulating immune responses at the mucosal surfaces of the gastrointestinal tract.     

Hydrolysis and absorption of lysozyme in the small intestine]

Preparations of chicken small intestine were used in the experiment in vitro simulating processes of membranous digestion (inverted intestinal segments) and absorption (inverted intestinal myasis). It was established that lysozyme was hydrolyzed on the internal mucosa surface regardless of its concentration in the gastro-intestinal tract, and only insignificant quantity of lysozyme (0.027%) penetrates the intestinal wall. The method of lysozyme determination through its action on the cellular wall of Micrococcus lisodeicticus, and highly efficient liquid chromatography were used to study the transport process. The data presented have evidenced that lysozyme is well hydrolyzed under the action of intestinal peptide hydrolyses, and only insignificant amounts of non-splitted lysozyme can penetrate the blood.     

Structural characteristics of the small intestine mucosa of rats on diets with varying amounts of protein

The small bowel mucosa of rats fed diets containing 4 and 35% of protein in terms of caloricity over 1 month demonstrated, as compared with control (18% of protein), alterations in the nuclei, in the degree of lymphoid infiltration, number of mitoses and gobiet cells in the epithelium, pointing to changes or impairment of maturation and differentiation of the cells of the epithelial layer. The degree of mucosa plasmatization was also discovered to be reduced as compared with control. The rearrangements in question attest to a decrease in the resistance of the mucosa. These rearrangements are more demonstrable in the intestine of rats which received low-protein diets, being far more pronounced in the distal parts.     

Effect of enterally administrated oxygenated water on electrical activity of the small intestine in early postoperative period in rats

The effect of oxygen, structurally-binded with water (oxygen water), on electrical activity of rat jejunum in early postoperative period. It was shown, that in contrast to effect of 0.9% NaCl, there is normalization of electrical activity parameters (frequency and slow wave amplitude) of jejunum in early postoperative period under the influence of oxygen water.     

青春双歧杆菌的耐氧驯化及不同低聚糖对其增殖效果的影响

为改善青春双歧杆菌在发酵产品中活菌数低、菌种功效弱的情况,对厌氧青春双歧杆菌进行耐氧驯化,采用无氧有氧交替驯化法,在驯化过程中逐渐增加青春双歧杆菌培养液的氧分压,测定青春双歧杆菌驯化前后生理特性,并对比大豆低聚糖、低聚木糖、低聚麦芽糖对青春双歧杆菌增殖的影响。结果表明,青春双歧杆菌在耐氧驯化后对氧气的敏感程度下降,有氧条件下生长能力达标,产酸能力得到提升,菌体驯化前后形态基本一致,耐氧青春双歧杆菌代谢产生的乙酸与乳酸比值较厌氧青春双歧杆菌更适宜发酵,在3种低聚糖中,低聚木糖对青春双歧杆菌增殖作用明显,可作为青春双歧杆菌良好的双歧因子。耐氧驯化后的青春双歧杆菌有着优良的生理特性,能够作为潜在的益生菌菌种深入研究其功能并可应用于发酵食品中。     

Cathepsin B and D activity in the mucous membrane of the small intestine of rats on a high-saccharose diet and added selenium

Selenium added to diets (700-750 micrograms per kg bw) enhanced the activity of cathepsins B and D; in this case, the protein content in the rat small intestine mucosa was found to be considerably reduced. High-sucrose diet did not directly influence the lysosomal proteinase activity, but enhanced selenium action on the proteolysis.