婴儿源益生性双歧杆菌的筛选及肠道定殖性研究

本研究旨在从婴儿粪便中筛选出具有潜在益生特性的双歧杆菌,并探究其肠道定殖情况,为双歧杆菌的产品开发提供优良的菌株。采用MRS培养基对样品进行分离纯化,菌株经F6PPK检测及16S r DNA测序鉴定,之后进行模拟胃肠液、胆盐耐受性、对食源性致病菌(大肠杆菌、沙门氏菌、单增李斯特菌等)的抑制及对HT-29细胞的粘附能力测定,将筛选出的菌株进行动物实验,测定其肠道定殖能力。分离到的27株双歧杆菌,经分子生物学鉴定为7个不同的种:Bifidobacterium longum、Bifidobacterium breve、Bifidobacterium bifidum、Bifidobacterium pseudocatenulatum、Bifidobacterium infantis、Bifidobacterium animalis和Bifidobacterium adolescentis。体外实验表明,B.longum A9、B.breve A4、B.bifidum B6、B.longum C6、B.adolescentis F8和B.infantis H6等具有较强的潜在益生特性;动物实验表明,B.infantis H6和B.longum C6具有较强的肠道定殖能力。B.longum C6和B.infantis H6有望作为优良的益生性菌株,应用于双歧杆菌的产品开发。     

Use of tuf gene-based primers for the PCR detection of probiotic Bifidobacterium species and enumeration of bifidobacteria in fermented milk by cultural and quantitative real-time PCR methods

Due to the increasing use of bifidobacteria in probiotic products, it is essential to establish a rapid method for the qualitative and quantitative assay of the bifidobacteria in commercial products. In this study, partial sequences of the tuf gene for 18 Bifidobacterium strains belonging to 14 species were determined. Alignment of these sequences showed that the similarities among these Bifidobacterium species were 82.24% to 99.72%. Based on these tuf gene sequences, 6 primer sets were designed for the polymerase chain reaction (PCR) assay of B. animalis subsp. animalis, B. animalis subsp. lactis, B. bifidum, B. breve, B. longum subsp. infantis, B. longum subsp. longum, and the genus of Bifidobacterium, respectively. These Bifidobacterium species are common probiotic species present in dairy and probiotic products. When each target Bifidobacterium spp. was assayed with the designed primers, PCR product with expected size was generated. In addition, for each target species, more than 70 bacterial strains other than the target species, including strains of other Bifidobacterium species, strains of Lactobacillus spp., Enterococcus spp., and other bacterial species, all generated negative results. PCR assay with primers specific to B. animalis subsp. lactis and B. longum subsp. longum confirmed the presence of these Bifidobacterium species in commercial yogurt products. In addition, for each product, enumeration of the bifidobacteria cells by culture method with BIM-25 agar and the quantitative real-time PCR showed similar cell counts. Such results indicated that within 15-d storage (4 °C) after manufacture, all the bifidobacteria cells originally present in yogurt products were viable and culturable during the storage.     

Production of oligosaccharides in yogurt containing bifidobacteria and yogurt cultures

Yogurts were prepared by using yogurt cultures combined to mixed cultures of bifidobacteria (Bifidobacterium animalis, Bifidobacterium bifidum, Bifidobacterium breve, Bifidobacterium infantis, and Bifidobacterium longum) and by adding a preincubation step (1.5 h at 50 degrees C) with bifidobacteria to the conventional method of manufacture in order to produce oligosaccharides. The survival of bifidobacteria was drastically affected during storage of yogurts, except for products containing B. animalis, in which viable counts remained at >10(6) cfu/g after 28 d of storage at 4 degrees C. Oligosaccharides with a degree of polymerization of 3 were produced during the preincubation step (0.31 to 0.68%), and the amount in the final products varied according to the species of bifidobacteria inoculated during the preincubation step or the concentration of bifidobacteria used as second inoculum during the fermentation process. In fact, the higher concentration of oligosaccharides measured at the end of the fermentation process (0.72%) and the 28 d-storage period (0.67%) was obtained for yogurts containing B. infantis. However, yogurts containing B. breve showed higher beta-galactosidase activities and had lower lactose concentrations after the fermentation process and the storage period than the other yogurts. The use of a mixed cultures of bifidobacteria (B. animalis, B. infantis, or B. breve) thus allows the production of yogurts in which bifidobacteria can survive in relatively high cell numbers and contain appreciable amount of oligosaccharides.     

In vitro fermentability of human milk oligosaccharides by several strains of bifidobacteria

This study was conducted to investigate the catabolism and fermentation of human milk oligosaccharides (HMO) by individual strains of bifidobacteria. Oligosaccharides were isolated from a pooled sample of human milk using solid-phase extraction, and then added to a growth medium as the sole source of fermentable carbohydrate. Of five strains of bifidobacteria tested (Bifidobacterium longum biovar infantis, Bifidobacterium bifidum, Bifidobacterium longum biovar longum, Bifidobacterium breve, and Bifidobacterium adolescentis), B. longum bv. infantis grew better, achieving triple the cell density then the other strains. B. bifidum did not reach a high cell density, yet generated free sialic acid, fucose and N-acetylglucosamine in the media, suggesting some capacity for HMO degradation. Thin layer chromatography profiles of spent fermentation broth suggests substantial degradation of oligosaccharides by B. longum bv. infantis, moderate degradation by B. bifidum and little degradation by other strains. While all strains were able to individually ferment two monosaccharide constituents of HMO, glucose and galactose, only B. longum bv. infantis and B. breve were able to ferment glucosamine, fucose and sialic acid. These results suggest that as a potential prebiotic, HMO may selectively promote the growth of certain bifidobacteria strains, and their catabolism may result in free monosaccharides in the colonic lumen.     

婴儿粪便长双歧杆菌的分离与多样性分析

本研究旨在分析婴儿粪便长双歧杆菌的多样性,采用改良MRS培养基从哈尔滨地区健康婴儿粪便中分离双歧杆菌,采用生理生化实验结合16S rDNA和热应激蛋白60基因(heat-shock protein 60,hsp60)同源性分析鉴定分离株,利用同源性分析及随机扩增多态性DNA(random amplified polymorphism DNA,RAPD)、多位点序列分型(multilocus sequence typing,MLST)技术进一步分析长双歧杆菌多态性。实验从11个婴儿体内分离得到18株厌氧的细菌菌株,经形态学分析、生理生化实验、16S rDNA测序及hsp60测序实验发现,其中7株为长双歧杆菌长亚种,3株为长双歧杆菌婴儿亚种。RAPD和MLST结果表明:7株长双歧杆菌长亚种为6个基因型,3株长双歧杆菌婴儿亚种为2个基因型,上述结果说明不同人源婴儿粪便长双歧杆菌基因型差异较大。     

双歧杆菌抗消化道逆环境特性的研究

应用模拟胃液pH、胃液、肠液、肠胆盐环境 ,研究青春双歧杆菌、婴儿双歧杆菌、长双歧杆菌和短双歧杆菌的抗消化道逆环境特性。在pH1 5酸性条件下作用 1 5h ,存活率分别为 0 14 %、17 86%、49 0 9%和 9 5 3 %。在加有胃蛋白酶的模拟胃液中作用 1 5h ,存活率分别为 :45 3 9%、97 2 7%、84 5 3 %和 85 5 1%。在含胰蛋白酶的模拟肠液中作用 12h ,存活率分别为 :2 9 17%、47 97%、87 70 %和 77 2 7%。青春双歧杆菌、长双歧杆菌和短双歧杆菌的活菌数随胆盐浓度升高而下降 ,2 %胆盐浓度条件下作用 12h ,三者的存活率分别为 5 92 %、13 96%和 61 2 4%。而婴儿双歧杆菌在各胆盐浓度条件下 ,均有生长趋势 ,这种趋势随胆盐浓度升高而下降。研究结果表明 ,消化道逆环境对双歧杆菌的存活有不同程度的影响 ,以婴儿双歧杆菌和长双歧杆菌的耐性最好。     

Viability of lactic acid bacteria and bifidobacteria in fermented soymilk after drying, subsequent rehydration and storage

To develop a probiotic dietary adjunct, soymilk fermented with various combinations of lactic acid bacteria (Streptococcus thermophilus and Lactobacillus acidophilus) and bifidobacteria (Bifidobacterium longum and Bifidobacterium infantis) was subjected to freeze-drying and spray-drying. Survival of the starter organisms during the drying process, subsequent rehydration at different temperatures and during a 4-month period of storage under different storage conditions was examined. After freeze-drying, lactic acid bacteria and bifidobacteria exhibited a survival percent of 46.2-75.1% and 43.2-51.9%, respectively, higher than that noted after spray-drying. Regardless of the drying condition, S. thermophilus showed a higher percentage of survival than L. acidophilus, while B. longum survived better than B. infantis. Further study with soymilk fermented with S. thermophilus and B. longum revealed that the freeze-dried and spray-dried fermented soymilk rehydrated at 35-50 degrees C and 20 degrees C, respectively, was optimum for the recovery of the starter organisms. Both S. thermophilus and B. longum survived better in the freeze-dried than the spray-dried fermented soymilk during storage. A higher percent of survival was also noted for both the starter organisms when the dried fermented soymilk was stored at 4 degrees C than 25 degrees C. Holding the dried fermented soymilk in the laminated pouch enabled S. thermophilus and B. longum to exhibit a higher percentage of survival than in the deoxidant- and desiccant-containing glass or polyester (PET) bottle. Among all the packaging materials and storage temperatures tested, starter organisms were most stable in the dried fermented soymilk held in laminated pouch and stored at 4 degrees C. Under this storage condition, S. thermophilus and B. longum showed a survival percentage of 51.1% and 68.8%, respectively, in the freeze-dried fermented soymilk after 4 months of storage. Meanwhile, S. thermophilus and B. infantis in the spray-dried fermented soymilk showed a survival percent of 29.5% and 57.7%, respectively.     

Use of chemical mutagenesis for the isolation of food grade beta-galactosidase overproducing mutants of bifidobacteria, lactobacilli and Streptococcus thermophilus

A classical chemical mutagenesis protocol was evaluated for increasing beta-galactosidase production by probiotic bacteria to improve their potential to treat symptoms of lactose malabsorption in humans. Two Bifidobacterium species (B. breve and B. longum) and one strain each of Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus were tested by a single exposure to two chemical mutagens, ethyl methanesulfonate (EMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). To screen for beta-galactosidase (beta-gal) overproducing mutants, optimized EMS and MNNG mutant pots for each strain were plated on BHI agar containing 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-gal). Colonies that exhibited a blue color were selected for quantitative beta-gal activities using the o-nitrophenyl-beta-galactoside (ONPG) assay. Seventy-five mutants were obtained out of more than 2 million colonies screened and showed increased beta-galactosidase activities compared with the wild-type strains. EMS gave a higher frequency of beta-gal overproducing mutants than MNNG for three of the four strains, S. thermophilus, B. breve, and B. longum, whereas the frequency of L. delbrueckii ssp. bulgaricus beta-gal mutants was similar with both mutagens. The highest beta-gal increases, when induced during growth in lactose, for mutants of each culture were 137% for L. delbrueckii ssp. bulgaricus; 104% for S. thermophilus; 70% for B. breve; and 222% for B. longum mutants. This food-grade classical approach has the ability to moderately increase beta-gal concentrations in probiotic cultures to improve their potential for treating the symptoms of lactose malabsorption in humans.     

Stability of bifidobacteria in powdered formula

Two stability tests of bifidobacteria in powdered formula were conducted. In a strain comparison test, three kinds of bifidobacterial powders; Bifidobacterium longum BB536, Bifidobacterium breve M-16V and Bifidobacterium infantis M-63 powders, admixed in follow-up formula were used. In a commercial product evaluation, powdered formulas for toddlers containing bifidobacteria sold in the Indonesian market were analysed. When the inactivation rate constant of each sample, which was used as an index of the loss rate, was determined from the stability tests, B. longum was the most stable strain. The mean inactivation rate constant of commercial products was significantly lower than those obtained in strain comparison, although the same strains ( B. longum BB536 and B. breve M-16V) were used. A possible reason was the lower water activity of commercial products compared to the follow-up formula. Also, higher storage temperature yielded lower stability in all strains or samples, which obeys the Arrhenius theory.     

Ingestion of yogurt containing Lactobacillus acidophilus and Bifidobacterium to potentiate immunoglobulin A responses to cholera toxin in mice

Lactic acid bacteria have been reported to have benefits for the prevention and treatment of some forms of diarrhea and related conditions. To determine whether these effects might involve direct stimulation of the gastrointestinal immune response, we administered yogurt to try to enhance mucosal and systemic antibodies against an orally presented immunogen, cholera toxin. Yogurts were manufactured with starter cultures containing different species and strains of lactic acid bacteria. Mice were fed these yogurts for 3 wk, during which they were also orally immunized twice with 10 micrograms of cholera toxin. Blood was collected on d 0 and 21, and fecal pellets were collected weekly. Mice that were immunized orally with cholera toxin responded by producing specific intestinal and serum immunoglobulin (Ig)A anti-cholera toxin. Antibody responses of the IgA isotype were significantly increased in mice fed yogurts made with starters containing the conventional yogurt bacteria Lactobacillus bulgaricus and Streptococcus thermophilus supplemented with Lactobacillus acidophilus, Bifidobacterium bifidum, and Bifidobacterium infantis. Yogurt that was manufactured with starters containing only conventional yogurt bacteria produced less IgA anti-cholera toxin than did the control group fed nonfat dry milk. Although strong responses were also observed for IgG anti-cholera toxin in serum, the responses did not differ among groups. Thus, administration of yogurt supplemented with L. acidophilus and Bifidobacterium spp. enhanced mucosal and systemic IgA responses to the cholera toxin immunogen.     

Relationship between oxygen sensitivity and oxygen metabolism of Bifidobacterium species.

Bifidobacteria, which are obligate anaerobes, were studied to determine the relationship between their sensitivity to oxygen and oxygen metabolism. Among the four species tested, Bifidobacterium infantis, Bifidobacterium breve, and Bifidobacterium longum differed from Bifidobacterium adolescentis in sensitivity to oxygen. The former three species showed marked growth under conditions of partial aeration, whereas the growth of B. adolescentis was suppressed by low concentrations of oxygen. Bifidobacteria express reduced NAD-oxidase and -peroxidase activities, which function in a pathway for two-electron reduction of molecular oxygen, producing hydrogen peroxide and, subsequently, water. Activities of reduced NAD-oxidase and -peroxidase were inversely correlated with their sensitivities to oxygen. Bifidobacterium adolescentis exhibited lowered activities of these two enzymes; the activities were 10 to 20% of those observed with B. infantis, B. breve, and B. longum. These observations are compatible with the hypothesis that reduced NAD-oxidase and reduced NAD-peroxidase in Bifidobacterium species play a role in prevention of oxygen toxicity. Superoxide dismutase activity was also detected in Bifidobacterium species. Superoxide dismutase is probably not involved in detoxification of oxygen, because the activity of this enzyme was extremely low, and the sensitivity to oxygen varied independently of superoxide dismutase activity.     

新疆喀什地区维吾尔族母乳源双歧杆菌分离筛选及其益生特性分析

采用多重聚合酶链式反应指纹图谱结合16S rRNA基因测序技术对新疆喀什地区维吾尔族母乳分离的双歧杆菌进行鉴定和遗传差异分析,并检测常规生理生化和糖代谢表型特征,同时测试菌株对6 种常见病原菌和3 种母乳源条件致病菌的抑菌性能和对胃肠液的耐受性。结果显示,15 份母乳样品中共分离15 株双歧杆菌,测序结果将菌株归属于3 个种以及2 个亚种,包括8 株假小链双歧杆菌（Bifidobacterium pseudocatenulatum）、2 株短双歧杆菌（B. breve）、2 株长双歧杆菌长亚种（B. longum subsp. longum）和3 株长双歧杆菌婴儿亚种（B. longum subsp. infantis）。抑菌实验表明,15 株测试菌株中,隶属于B. pseudocatenulatum的4 株菌MY92、MY75-1、MY72、MY81的抑菌谱更广,抑菌能力更强;胃肠液耐受性实验表明菌株MY92无论在模拟胃液还是模拟肠液中存活率均最高,分别达到20.37%和0.302%。基于以上描述特性,MY92作为一株有效的益生菌株,具有潜在的利用价值,为后期进一步作为防止婴幼儿腹泻辅助制剂的开发提供参考。     

Effects of fructooligosaccharide and whey protein concentrate on the viability of starter culture in reduced-fat probiotic yogurt during storage

ABSTRACT:  Viability of yogurt starter cultures and Bifidobacterium animalis was assessed during 28 d storage in reduced-fat yogurts containing 1.5% milk fat supplemented with 1.5% fructooligosaccharide or whey protein concentrate. These properties were examined in comparison with control yogurts containing 1.5% and 3% milk fat and no supplement. Although fructooligosaccharide improved the viability of Streptococcus thermophilus , Lactobacillus delbrueckii subs. bulgaricus, and Bifidobacterium animalis , the highest growth was obtained when milk was supplemented with whey protein concentrate in reduced-fat yogurt ( P < 0.05). Supplementation with 1.5% whey protein concentrate in reduced-fat yogurt increased the viable counts of S. thermophilus , L. delbrueckii subs. bulgaricus, and B. animalis by 1 log cycle in the 1st week of storage when compared to control sample. Similar improvement in the growth of both yogurt bacteria and B. animalis was also obtained in the full-fat yogurt containing 3% milk fat and no supplement. Addition of whey protein concentrate also resulted in the highest content of lactic and acetic acids ( P < 0.05). A gradual increase was obtained in organic acid contents during the storage.     

Effects of milk products fermented by Bifidobacterium longum on blood lipids in rats and healthy adult male volunteers

The effects of milk products fermented by Bifidobacterium longum strain BL1, a probiotic strain, on blood lipids in rats and humans were studied. Rats were fed a cholesterol-enriched experimental diet, supplemented with lyophilized powders of 1) acid milk (control), 2) milk fermented with a mixed culture of ordinary yogurt starters composed of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (SL), and 3) bifidobacterium milk fermented with the probiotic B. longum strain BL1, respectively. The bifidobacterium milk feeding brought about significant lowering of the serum concentrations of total cholesterol, low-density lipoprotein cholesterol, and triglycerides, in comparison with the control, while no change in high-density lipoprotein cholesterol concentration was observed. On the other hand, supplementation with SL milk resulted in only slight, nonsignificant decreases in serum lipid concentrations in comparison with the control. In the human study, 32 subjects with serum total cholesterol ranging from 220 to 280 mg/dl were randomly assigned to two treatments: 1) intake of a low-fat drinking yogurt prepared with ordinary yogurt starters composed of S. thermophilus and L. delbrueckii subsp. bulgaricus (P-group) and 2) intake of a low-fat drinking yogurt prepared with the two ordinary yogurt starters plus B. longum strain BL1 (B-group). After intake for 4 wk at 3 x 100 ml/day, reduction of serum total cholesterol was observed in approximately half of the B-group subjects; a particularly significant decrease in serum total cholesterol was found among subjects with moderate hypercholesterolemia (serum total cholesterol > 240 mg/dl). However, the serum lipid concentrations in the P-group subjects were almost stable during the experimental periods. The present results indicate the potential of the probiotic B. longum strain BL1 in serum lipid improvement.     

Culture-dependent and culture-independent qualitative analysis of probiotic products claimed to contain bifidobacteria

A total of 58 probiotic products obtained worldwide, which were claimed to contain Bifidobacterium strains (including 22 yoghurts, 5 dairy fruit drinks, 28 food supplements and 3 pharmaceutical preparations) were investigated in parallel using a culture-dependent and a culture-independent approach. Three isolation media previously reported as selective for Bifidobacterium were evaluated for their suitability in the quality analysis of these products. Subsequently, possible bifidobacterial colonies were picked from the best medium and identified by means of rep-PCR fingerprinting using the BOX primer (BOX-PCR). Bifidobacterium animalis subsp. lactis, formerly classified as Bifidobacterium lactis, was most frequently found, but strains belonging to Bifidobacterium longum biotypes longum and infantis, Bifidobacterium bifidum and Bifidobacterium breve were recovered also. In parallel, all products were also subjected to culture-independent analysis which involved a nested-PCR step on total bacterial DNA extracted directly from the product, followed by separation of the amplicons by Denaturing Gradient Gel Electrophoresis (DGGE) and subsequent identification of species from the band patterns. By conventional cultivation, 70.7% of the products analysed were found to contain culturable bifidobacteria whereas by culture-independent DGGE analysis members of the genus Bifidobacterium could be detected in 96.5% of the analysed products. Genotypic characterization of a number of bifidobacterial isolates at the strain level by means of Pulsed-Field Gel Electrophoresis (PFGE) revealed a relatively high degree of genomic homogeneity among the Bifidobacterium strains currently used in the probiotic industry.     

双歧杆菌对仔猪小肠黏液糖蛋白的粘附研究

通过扫描电镜观察细菌在仔猪肠黏膜的粘附状况，发现肠道茵群与黏膜表面的黏液层有密切联系。采用放射性代谢标记方法研究所拥有的双歧杆菌与仔猪肠黏膜黏液糖蛋白的粘附，发现青春双歧杆菌的粘附能力最强，为44．61%；其次是短双歧杆菌，为33．20％；婴儿双歧杆菌和长双歧杆菌分别是18．40％和11．78％。结果表明，所实验的糖、初乳粉以及婴儿双歧杆菌、长双歧杆菌、大肠杆菌和沙门氏茵上清均能导致青春双歧杆菌粘附下降，而青春双歧杆菌和短双歧杆菌上清却有促进其粘附的作用。     

Viability of Bifidobacteria Strains in Yogurt with Added Oat Beta-Glucan and Corn Starch during Cold Storage

Abstract: Probiotics must be consumed at a level of 10⁷ CFU/mL for successful colonization of the gut. In yogurts containing beneficial cultures, the survival of probiotic strains can quickly decline below this critical concentration during cold storage. We hypothesized that beta-glucan would increase the viability of bifidobacteria strains in yogurt during cold storage. Yogurts were produced containing 0.44% beta-glucan (concentrated or freeze-dried) extracted from whole oat flour and/or 1.33% modified corn starch, and bifidobacteria (B. breve or B. longum) at a concentration of at least 10⁹ CFU/mL. All yogurts were stored at 4 °C. Bifidobacteria and yogurt cultures, Streptococcus thermophilus and Lactobacillus delbureckii subsp. bulgaricus, were enumerated from undisturbed aliquots before fermentation, after fermentation, and once a week for 5 wk. S. thermophilus and L. bulgaricus maintained a concentration of at least 10⁸ CFU/mL in yogurts containing concentrated or freeze-dried beta-glucan regardless of starch addition, and in the control with no added beta-glucan or starch. Similarly, the probiotic, Bifidobacterium breve, survived above a therapeutic level in all treatments. The addition of beta-glucan prolonged the survival of Bifidobacterium longum at a concentration of at least 10⁷ CFU/mL by up to 2 wk on average beyond the control. Further, the inclusion of concentrated beta-glucan in yogurt improved survival of B. longum above 10⁷ CFU/mL by 1 wk longer than did freeze-dried beta-glucan. Study results suggest that beta-glucan has a protective effect on bifidobacteria in yogurt when stressed by low-temperature storage. Practical Application: This study suggests that beta-glucan (oat fiber) may improve bifidobacteria survival in yogurt during refrigerated storage.     

An investigation of some properties of banana yogurts made with commercial ABT-2 starter culture during storage

Five yogurt batches were prepared with banana puree and sugar combinations and ABT-2 ( Streptococcus salivarius ssp. thermophilus, Lactobaccilus acidophilus and Bifidobacterium spp.) as starter culture. The addition of fruit influenced ( P <  0.05) the syneresis, titratable acidity and pH, whereas the viscosity value, and S. salivarius ssp. thermophilus, L. acidophilus and Bifidobacterium spp. counts were found to be insignificant. Storage time significantly ( P <  0.05) affected the syneresis, titratable acidity, pH value, and S. salivarius ssp. thermophilus counts, while the viscosity value and L. acidophilus and Bifidobacterium spp. counts were not affected. The sensory evaluations showed that the sample B was most preferred by panellists.     

Effects of ingestion of yogurts containing Bifidobacterium and Lactobacillus acidophilus on spleen and Peyer's patch lymphocyte populations in the mouse

Certain probiotic lactic acid bacteria have been reported to improve immune system function. Here, the effects of ingesting yogurts on lymphocyte populations in the spleens and Peyer's patches were determined in mice. Three probiotic-supplemented yogurts containing Streptococcus thermophilus, Lactobacillus bulgaricus, Bifidobacterium, and Lactobacillus acidophilus and one conventional yogurt containing only S. thermophilus and L. bulgaricus were prepared from commercial starter cultures and used in the study. B6C3F1 female mice were fed the four different types of yogurts mixed with an AIN-93G diet in a 50:50 (wt/wt) ratio. Nonfat dry milk mixed at a 50:50 (wt/wt) ratio with AIN-93G diet was used as the control. After a 14-day feeding period, spleen and Peyer's patches were removed and lymphocytes subjected to phenotype analysis by flow cytometry. Ingestion of the four yogurts had no effect on percentages of CD8+ (cytotoxic T cells), B220+ (B cells), IgA+, or IgM+ cells in spleen or Peyer's patches. The percentage of CD4+ (T helper) cells was significantly increased in the spleens from one group of mice fed a yogurt containing Bifidobacterium and L. acidophilus, and a similar trend was found in the remaining two probiotic-supplemented yogurts. Effects on CD4+ populations were not observed in spleens of mice fed conventional yogurt or in the Peyer's patches of any of the four yogurt groups. In total, the results suggested that ingestion of conventional or probiotic-supplemented yogurts for 2 weeks had very little effect on lymphocyte distribution in the systemic or mucosal immune compartments.     

Selection of phytate-degrading human bifidobacteria and application in whole wheat dough fermentation

Lately, whole wheat products are highly recommended from their healthy properties. However, the presence of phytic acid (InsP(6)) could partly limit their benefits because it decreases the mineral bioavailability due to its chelating properties. The objective of this work was to select strains with high phytate-degrading activity from human feces, and evaluate their suitability for the bread making process. Twenty-three different bifidobacterial strains (13 from infants and 10 from adults) were isolated, belonging to the species Bifidobacterium longum, Bifidobacterium breve and Bifidobacterium catenulatum. The phosphatase and phytase activities of these strains were evaluated as well as their ability to degrade InsP(6) during growth. Then, the fermentative ability of the strain showing the highest phytate-degrading activity (B. longum. BIF307) was determined in whole wheat breadmaking. The use of the selected bifidobacterial strain as starter during whole wheat fermentation resulted in bread with similar technological quality than the control (in absence of bifidobacteria) and crumb with lower levels of inositol phosphates. Therefore, the used of the selected Bifidobacterium strain in whole wheat breadmaking process could provide potential nutritional benefits by decreasing the antinutrient content of the product.