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Bifidobacteria in the infant faecal microbiota have been the focus of much interest, especially during the exclusive milk-feeding period and in relation to the fortification of infant formulae to better mimic breast milk. However, longitudinal studies examining the diversity and dynamics of the Bifidobacterium population of infants are lacking, particularly in relation to the effects of weaning. Using a polyphasic strategy, the Bifidobacterium populations of breast-and formula-fed infants were examined during the first 18 months of life. Bifidobacterium-specific denaturing gradient gel electrophoresis demonstrated that breast-fed infants harboured greater diversity than formula-fed infants and the diversity of the infants' Bifidobacterium populations increased with weaning. Twenty-seven distinctive banding profiles were observed from ~ 1100 infant isolates using ribosomal intergenic spacer analysis, 14 biotypes of which were confirmed to be members of the genus Bifidobacterium. Two profiles (H, Bifidobacterium longum subsp. infantis; and I, Bifidobacterium bifidum) were common culturable biotypes, seen in 9/10 infants, while profile E (Bifidobacterium breve) was common among breast-fed infants. Overall, inter- and intra-individual differences were observed in the Bifidobacterium populations of infants between 1 and 18 months of age, although weaning was associated with increased diversity of the infant Bifidobacterium populations. Breast-fed infants generally harboured a more complex Bifidobacterium microbiota than formula-fed infants. DOI 10.1099/mic.0.043224-0

Necrotizing enterocolitis (NEC) is a devastating intestinal disease of neonates, and clinical studies suggest the beneficial effect of probiotics in NEC prevention. Recently, we have shown that administration of Bifidobacterium bifidum protects against NEC in a rat model. Intestinal apoptosis can be suppressed by activation of cyclooxygenase-2 (COX-2) and increased production of prostaglandin [E.sub.2] ([PGE.sub.2]). The present study investigates the effect of B. bifidum on intestinal apoptosis in the rat NEC model and in an intestinal epithelial cell line (IEC-6), as a mechanism of protection against mucosal injury. Premature rats were divided into the following three groups: dam fed, hand fed with formula (NEC), or hand fed with formula supplemented with B. bifidum (NEC + B. bifidum). Intestinal Toll-like receptor-2 (TLR-2), COX-2, [PGE.sub.2], and apoptotic regulators were measured. The effect of B. bifidum was verified in IEC-6 cells using a model of cytokine-induced apoptosis. Administration of B. bifidum increased expression of TLR-2, COX-2, and [PGE.sub.2] and significantly reduced apoptosis in the intestinal epithelium of both in vivo and in vitro models. The Bax-to-Bcl-w ratio was shifted toward cell survival, and the number of cleaved caspase-3 positive cells was markedly decreased in B. bifidum-treated rats. Experiments in IEC-6 cells showed anti-apoptotic effect of B. bifidum. Inhibition of COX-2 signaling blocked the protective effect of B. bifidum treatment in both in vivo and in vitro models. In conclusion, oral administration of B. bifidum activates TLR-2 in the intestinal epithelium. B. bifidum increases expression of COX-2, which leads to higher production of [PGE.sub.2] in the ileum and protects against intestinal apoptosis associated with NEC. This study indicates the ability of B. bifidum to downregulate apoptosis in the rat NEC model and in IEC-6 cells by a COX-2-dependent matter and suggests a molecular mechanism by which this probiotic reduces mucosal injury and preserves intestinal integrity. epithelial homeostasis; enteral nutrition; mucosal inflammation; probiotics doi: 10.1152/ajpgi.00131.2010.

Bifidobacterium animalis subsp, lactis lives in the gastrointestinal tract of most mammals, including humans. Recently, for the probiotic strain B. animalis subsp, lactis BIO7, a dose-dependent plasminogen-binding activity was demonstrated and five putative plasminogen-binding proteins were identified. Here we investigated the role of surface DnaK as a B. animalis subsp. lactis BI07 plasminogen receptor. DnaK was visualized on the bacterial cell surface by transmission electron microscopy. The His-tagged recombinant DnaK protein showed a high affinity for human plasminogen, with an equilibrium dissociation constant in the nanomolar range. The capability to tolerate physiological concentrations of bile salts is a crucial feature for an intestinal symbiont micro-organism. By proteome analysis we demonstrated that the long-term exposure of B. animalis subsp, lactis BIO7 to bile salts results in the upregulation of important surface plasminogen receptors such as DnaK and enolase. Moreover, adaptation of B. animalis subsp, lactis BIO7 to physiological concentrations of bile salts significantly increased its capacity to interact with the host plasminogen system. By enhancing the bacterial capacity to interact with the host plasminogen, the gut bile environment may facilitate the colonization of the human host by B. animalis subsp, lactis BIO7. DOI 10.1099/mic.0.038307-0

The effect of four sugars (glucose, galactose, lactose and fructose) on exopolysaccharide (EPS) production by Bifidobacterium longum subsp, longum CRC 002 was evaluated. More EPS was produced when CRC 002 was grown on lactose in the absence of pH control, with a production of 1080 [+ or -] 120 mg EPS [I.sup-1] (P DOI 10.1099/mic.0.033720-0

Previous studies indicate that certain probiotic bacterial strains or their soluble products can alleviate proinflammatory cytokine secretion by intestinal epithelial cells (IEC), but their impact on epithelial chloride ([Cl.sup.-]) secretion remains elusive. To further decipher the mechanisms of the cross-talk between bacteria/soluble factors and epithelial cells, we analyzed the capacity of the probiotic strain Bifidobacterium breve C50 (Bb C50), its conditioned medium, and other commensal Gram (+) bacteria to modulate epithelial [Cl.sup.-] secretion. The effect of Bb C50 on carbachol- (CCh) or forskolin (Fsk)-induced [Cl.sup.-] secretion was measured in an IEC line in Ussing chambers. The mechanisms involved in the regulation of [Cl.sup.-] secretion were assessed by measuring intracellular [Ca.sup.2+] concentration, phosphatase activity, protein kinase (PK) C and PKA activation, and cystic fibrosis transmembrane conductance regulator (CFTR) expression. CCh- or Fsk-induced [Cl.sup.-] secretion [short-circuit current (Isc): 151 [+ or -] 28 and 98 [+ or -] 14 [micro]A/[cm.sup.2], respectively] was inhibited dose-dependently by Bb C50 (Isc 33 [+ or -] 12 and 49 [+ or -] 7 [micro]A/[cm.sup.2] at multiplicity of infection 100; P < 0.02). Fsk-induced [Cl.sup.-] secretion was also inhibited by Lactobacillus rhamnosus 10893. No other inhibitory effect was recorded with the other Gram (+) bacteria tested. The inhibitory effect of Bb C50 on CCh-induced [Cl.sup.-] secretion targeted a step downstream of epithelial [Ca.sup.2+] mobilization and was associated with decreased PKC activity. Thus, Bb C50 and secreted soluble factors, by inhibiting phosphorylation processes, may promote intestinal homeostasis by controlling [Cl.sup.-] secretion. J. Nutr. 140: 7-11, 2010. doi: 10.3945/jn.109.114553.

Members of the genus Bifidobacterium are gram-positive bacteria that commonly are found in the gastrointestinal tract (GIT) of mammals, including humans. Because of their perceived probiotic properties, they frequently are incorporated as functional ingredients in food products. From probiotic production to storage and GIT delivery, bifidobacteria encounter a plethora of stresses. To cope with these environmental challenges, they need to protect themselves through stress-induced adaptive responses. We have determined the response of B. breve UCC2003 to various stresses (heat, osmotic, and solvent) using transcriptome analysis, DNA-protein interactions, and GusA reporter fusions, and we combined these with results from an in silico analysis. The integration of these results allowed the formulation of a model for an interacting regulatory network for stress response in B. breve UCC2003 where HspR controls the SOS response and the CIgR regulon, which in turn regulates and is regulated by HrcA. This model of an interacting regulatory network is believed to represent the paradigm for stress adaptation in bifidobacteria. doi: 10.1128/JB.00897-09

The interaction with the host plasminogen/plasmin system represents a novel component in the molecular cross-talk between bifidobacteria and human host. Here, we demonstrated that the plasminogen-binding bifidobacterial species B. longum, B. bifidum, B. breve and B. lactis share the key glycolytic enzyme enolase as a surface receptor for human plasminogen. Enolase was visualized on the cell surface of the model strain B. lactis BI07. The His-tagged recombinant protein showed a high affinity for human plasminogen, with an equilibrium dissociation constant in the nanomolar range. By site-directed mutagenesis we demonstrated that the interaction between the B. lactis BI07 enolase and human plasminogen involves an internal plasminogen-binding site homologous to that of pneumococcal enolase. According to our data, the positively charged residues Lys-251 and Lys-255, as well as the negatively charged Glu-252, of the B. lactis BIO7 enolase are crucial for plasminogen binding. Acting as a human plasminogen receptor, the bifidobacterial surface enolase is suggested to play an important role in the interaction process with the host. DOI 10.1099/mic.0.028795-0

Host--bacteria interactions are often mediated via surface-associated proteins. The identification of these proteins is an important goal of bacterial proteomics. To address how bile can influence the cell-envelope proteome of Bifidobacterium Iongum biotype Iongum NCIMB 8809, we analysed its membrane protein fraction using stable isotope labelling of amino acids in cell culture (SlLAC). We were able to identify 141 proteins in the membrane fraction, including a large percentage of the theoretical transporters of this species. Moreover, the envelope-associated soluble fraction was analysed using different subfractionation techniques and differential in-gel fluorescence electrophoresis (DIGE). This approach identified 128 different proteins. Some of them were well-known cell wall proteins, but others were highly conserved cytoplasmic proteins probably displaying a 'moonlighting' function. We were able to identify 11 proteins in the membrane fraction and 6 proteins in the envelope-associated soluble fraction whose concentration varied in the presence of bile. Bile promoted changes in the levels of proteins with important biological functions, such as some ribosomal proteins and enolase. Also, oligopeptide-binding proteins were accumulated on the cell surface, which was reflected in a different tripeptide transport rate in the cells grown with bile. The data reported here will provide the first cell-envelope proteome map for B. longum, and may contribute to understanding the bile tolerance of these bacteria.

Bifidobacteria represent one of the most important health-promoting bacterial groups of the intestinal microbiota. The binding of plasminogen to species of Bifidobacterium has been recently reported. To further explore the interaction between bifidobacteria and plasminogen, we investigated the role of Bifidobacterium lactis BI07 plasminogen-dependent proteolytic activity in the degradation of host-specific substrates. Our experimental data demonstrate that the recruitment of plasminogen on the bacterial cell surface and its subsequent conversion into plasmin by host-derived plasminogen activators provide B. lactis BI07 with a surface-associated plasmin activity effective in degradation of physiological substrates such as extracellular matrix, fibronectin and fibrinogen. The ability of bifidobacteria to intervene in the host plasminogen/ plasmin system may contribute to facilitating colonization of the host gastrointestinal tract.

One of the two Bifidobacterium asteroides strains containing plasmids are selected for analysis of its replication functions and for construction of Escherichia coli-Bifidobacterium shuttle vectors. The results have shown that these shuttle vectors are capable of transforming various bifidobacteria with an efficiency of up to [10.sup.6] tranformants/[micro]g DNA.

The functions of the enzymes encoded by the lnpB, lnpC, and lnpD genes, located downstream of the lacto-N-biose phosphorylase gene (lnpA) are determined in Bifidobacterium longum JCM1217. The results of the study suggest that the gene operon InpABCD encodes an undescribed lacto-N-biose I/galacto-N-biose metabolic pathway.

Acid response and adaptation in a Bifidobacterium longum biotype longum and its acid-pH-resistant mutant are studied. The adaptation and response to low pH in Bifidobacterium longum biotype longum involve changes in the glycolytic flux and in the ability to regulate the internal pH.

Bifidobacteria constitute up to 3% of the total microbiota and represent one of the most important health-promoting bacterial groups of the human intestinal microflora. The presence of Bifidobacterium in the human gastrointestinal tract has been directly related to several health-promoting activities; however, to date, no information about the specific mechanisms of interaction with the host is available. In order to provide some insight into the molecular mechanisms involved in the interaction with the host, we investigated whether Bifidobacterium was able to capture human plasminogen on the cell surface. By using flow cytometry, we demonstrated a dose-dependent human plasminogen-binding activity for four strains belonging to three bifidobacterial species: Bifidobacterium lactis, B. bifidum, and B. longum. The binding of human plasminogen to Bifidobacterium was dependent on lysine residues of surface protein receptors. By using a proteomic approach, we identified five putative plasminogen-binding proteins in the cell wall fraction of the model strain B. lactis BI07. The data suggest that plasminogen binding to B. lactis is due to the concerted action of a number of proteins located on the bacterial cell surface, some of which are highly conserved cytoplasmic proteins which have other essential cellular functions. Our findings represent a step forward in understanding the mechanisms involved in the Bifidobacterium-host interaction.

The 16S rRNA-based analyses are applied to the intestinal microbiota of chimpanzees in the wild and in captivity in order to estimate their similarities and differences in individual chimpanzees in both locations. Several bacteria such as the Clostridium leptum subgroup bacteria, Lactobacillus gasseri-like bacterium and Bifidobacterium pseudocatenulatum- or B. catenulatum-like bacteria are found to be common for both wild and captive chimpanzees.

In silico analysis of the Bifidobacterium breve UCC2003 genome has helped in identifying the four genetic loci, each of which has specified a putative enzyme II (EII) protein of a phosphoenolpyruvate:sugar phosphotransferase system. Biochemical studies have shown that FruA has phosphorylated fructose at the C-6 position.

Pre- and/or probiotics can cause changes in the ecological balance of intestinal microbiota and hence influence microbial metabolic activities. In the present study, the influence of oligofructose-enriched inulin (OF-IN), Lactobacillus casei Shirota, and Bifidobacterium breve Yakult on the colonic fate of N[H.sub.3] and p-cresol was investigated. A randomized, placebo-controlled, crossover study was performed in 20 healthy volunteers to evaluate the influence of short- and long-term administration of OF-IN, L. casei Shirota, B. breve Yakult, and the synbiotic L. casei Shirota + OF-IN. The lactose[[sup.15]N, [sup.15]N]ureide biomarker was used to study the colonic fate of N[H.sub.3]. Urine and fecal samples were analyzed for [sup.15]N content by combustion-isotope ratio mass spectrometery and for p-cresol content by gas chromatography-mass spectrometry. RT-PCR was applied to determine the levels of total bifidobacteria. Both short- and long-term administration of OF-IN resulted in significantly decreased urinary p-cresol and [sup.15]N content. The reduction of urinary [sup.15]N excretion after short-term OF-IN intake was accompanied by a significant increase in the [sup.15]N content of the fecal bacterial fraction. However, this effect was not observed after long-term OF-IN intake. In addition, RT-PCR results indicated a significant increase in total fecal bifidobacteria after long-term OF-IN intake. Long-term L. casei Shirota and B. breve Yakult intake showed a tendency to decrease urinary [sup.15]N excretion, whereas a significant decrease was noted in p-cresol excretion. In conclusion, dietary addition of OF-IN, L. casei Shirota, and B. breve Yakult results in a favorable effect on colonic N[H.sub.3] and p-cresol metabolism, which, in the case of OF-IN, was accompanied by an increase in total fecal bifidobacteria. ammonia; p-cresol; bifidobacteria; biomarker

The effects of [O.sub.2] on Bifidobacterium species was investigated using liquid shaking cultures under various [O.sub.2] concentrations. It was observed that [H.sub.2]O-forming NADH oxidase activities were detected dominantly in cell extracts of B. boum and B. thermophilum under acidic reaction conditions.

The effect of Bifidobacterium lactis (Bb-12) and Lactobacillus salivarius (UCC500) on the formation of carboxylic acids (CAs) was studied in the hindgut of rats fed pectin, inulin of low solubility, and lactitol. When the pectin diet was supplemented with Bb-12, the formation of CAs was larger throughout the colon of rats, due to increased formation of acetic acid (P < 0.01) and, in the distal part of the colon, also because of propionic and butyric acids (P < 0.01). In rats fed pectin and UCC500, there was a shift in the formation of CAs from the cecum to the distal colon. Thus, the cecal pool of CAs in the rats was lower (P < 0.05), whereas the concentration of CAs in the distal part of colon was larger (P < 0.01) than without this strain. Concerning the slowly fermentable inulin, there was a greater formation of CAs in the cecum (P < 0.05) of rats, especially propionic acid, and a lower formation in the distal part of the colon (P < 0.01) when the diets were supplemented with Bb-12, whereas UCC500 had no effect except for a lower proportion of acetic acid in the distal part of the colon (P < 0.001). In rats fed lactitol and Bb12, the concentration of CAs was lower in the distal part of colon (P < 0.001) than without this strain, whereas the cecal pool of CAs was greater in rats supplemented with UCC500 (P < 0.001). We conclude that the probiotic bacteria affect the amount, the pattern, and the site of release of CAs in the hindgut of rats, but the combination of pre- and probiotics is of great importance for the outcome.

The genetic characterization of the Bifidobacterium breve UCC 2003 hrcA-dnaJ2 genes, which appear to represent a third pattern of controlled expression of chaperone-encoding genes in the genus Bifidobacterium, is described. The observed induction pattern is unlike those of other characterized dnaJ genes and it might be indicative of a unique stress adaptation strategy by this commensal microorganism.

Nine pure or mixed broth media are evaluated for their suitabilities to investigate MICs in a microdilution test of 19 antibacterial agents for lactic acid bacteria (LAB) of the genera Lactobacillus, Pediococcus, Lactococcus and Bifidobacterium. The LAB susceptibility test medium has provided the most optimal medium basis in terms of growth support of nonenterococcal LAN and correct indication of MICs of international control strains.

The first complete cloning, purification and characterization of a proteolytic enzyme in Bifidobacterium animalis subsp. lactis to utilize milk proteins and milk-derived peptides are reported. The activity of B. animalis subsp. lactis endopeptidase (PepO) is found with oligopeptide substrates of many amino acid residues and the predominant peptide bond is on the N-terminal side of phenylalanine residues.

Five clp genes (clpC, clpB, clpP1, clpP2, and clpX), representing chaperone- and protease-encoding genes, were previously identified in Bifidobacterium breve UCC 2003. In the present study, we characterize the B. breve UCC 2003 clpP locus, which consists of two paralogous genes, designated clpP1 and clpP2, whose deduced protein products display significant similarity to characterized ClpP peptidases. Transcriptional analyses showed that the clpP1 and clpP2 genes are transcribed in response to moderate heat shock as a bicistronic unit with a single promoter. The role of a clgR homologue, known to control the regulation of clpP gene expression in Streptomyces lividans and Corynebacterium glutamicum, was investigated by gel mobility shift assays and DNase I footprint experiments. We show that ClgR, which in its purified form appears to exist as a dimer, requires a proteinaceous cofactor to assist in specific binding to a 30-bp region of the clpP promoter region. In pull-down experiments, a 56-kDa protein copurified with ClgR, providing evidence that the two proteins also interact in vivo and that the copurified protein represents the cofactor required for ClgR activity. The prediction of the ClgR three-dimensional structure provides further insights into the binding mode of this protein to the clpP1 promoter region and highlights the key amino acid residues believed to be involved in the protein-DNA interaction.

A traditional table olive was used and investigated as a vehicle for incorporating probiotic bacterial species at room temperature to develop new functional foods. The results showed that bifidobacteria and one strain of Lactobacillus rhamnosus (Lactobacillus GG) showed a good survival rate with a recovery of about 10(super 6)CFUg(super -1) after 30 days.

A new approach combining a flow cytometric in situ viability assessment with 16S rRNA gene analysis was developed to obtain insight into the genetic diversity and activity of the fecal microbiota. Phylogenetic analysis of the live, dead and injured cells revealed a remarkable physiological heterogeneity within the bacterial populations, Bifidobacterium longum and B. infantis were retrieved from all sorted fractions, while B. adolescentis was recovered mostly from the sorted dead fraction.

Adaptation to and tolerance of bile stress are among the main limiting factors to ensure survival of bifidobacteria in the intestinal environment of humans. The effect of bile salts on protein expression patterns of Bifidobacterium longum was examined. Protein pattern comparison of strains grown with or without bile extract allowed us to identify 34 different proteins whose expression was regulated. The majority of these proteins were induced after both a minor (0.6 g [liter.sup.-1]) and a major (1.2 g [liter.sup.-1]) exposure to bile. These include general stress response chaperones, proteins involved in transcription and translation and in the metabolism of amino acids and nucleotides, and several enzymes of glycolysis and pyruvate catabolism. Remarkably, xylulose 5-phosphate/fructose 6-phosphate phosphoketolase, the key enzyme of the so-called bifidobacterial shunt, was found to be upregulated, and the activity on fructose 6-phosphate was significantly higher for protein extracts of cells grown in the presence of bile. Changes in the levels of metabolic end products (acetate and lactate) were also detected. These results suggest that bile salts, to which bifidobacteria are naturally exposed, induce a complex physiological response rather than a single event in which proteins from many different functional categories take part. This study has extended our understanding of the molecular mechanism underlying the capacity of intestinal bifidobacteria to tolerate bile.

Although the ability of Bifidobacterium spp. to grow on fructose as a unique carbon source has been demonstrated, the enzyme(s) needed to incorporate fructose into a catabolic pathway has hitherto not been defined. This work demonstrates that intracellular fructose is metabolized via the fructose-6-P phosphoketolase pathway and suggests that a fructokinase (Frk; EC 2.7.1.4) is the enzyme that is necessary and sufficient for the assimilation of fructose into this catabolic route in Bifidobacterium longum. The B. longum A10C fructokinase-encoding gene (frk) was expressed in Escherichia coli from a pET28 vector with an attached N-terminal histidine tag. The expressed enzyme was purified by affinity chromatography on a C[O.sub.2+]-based column, and the pH and temperature optima were determined. A biochemical analysis revealed that Frk displays the same affinity for fructose and ATP ([K.sub.m.sup.fructose] = 0.739 [+ or -] 0.18 mM and [K.sub.m.sup.ATP] = 0.756 [+ or -] 0.08 mM), is highly specific for D-fructose, and is inhibited by an excess of ATP (>12 mM). It was also found that frk is inducible by fructose and is subject to glucose-mediated repression. Consequently, this work presents the first characterization at the molecular and biochemical level of a fructokinase from a gram-positive bacterium that is highly specific for D-fructose.

A genomic library of Bifidobacterium bifidum constructed in Escherichia coli was screened for the ability to hydrolyze the [alpha]-(1 [right arrow] 2) linkage of 2'-fucosyllactose, and a gene encoding 1,2-[alpha]-L-fucosidase (AfcA) was isolated. The afcA gene was found to comprise 1,959 amino acid residues with a predicted molecular mass of 205 kDa and containing a signal peptide and a membrane anchor at the N and C termini, respectively. A domain responsible for fucosidase activity (the Fuc domain; amino acid residues 577 to 1474) was localized by deletion analysis and then purified as a hexahistidine-tagged protein. The recombinant Fuc domain specifically hydrolyzed the terminal [alpha]-(1 [right arrow] 2)-fucosidic linkages of various oligosaccharides and a sugar chain of a glycoprotein. The stereochemical course of the hydrolysis of 2'-fucosyllactose was determined to be inversion by using [sup.1]H nuclear magnetic resonance. The primary structure of the Fuc domain exhibited no similarity to those of any glycoside hydrolases (GHs) but showed high similarity to those of several hypothetical proteins in a database. Thus, it was revealed that the AfcA protein constitutes a novel inverting GH family (GH family 95).

The strains of the genus Bifidobacterium was isolated and genomically characterized, by using pulsed-field gel electrophoresis, from infant feces so that the genetically distinct strains could be assessed for their ability to produce the beneficial fatty acid conjugated linoleic acid (CLA) from free linoleic acid. The ability of particular strains to efficiently produce CLA influences the choice of bifidobacteria for supplementation in neonatal infants at risk of necrotizing enterocolitis.

The effect of lactic acid and commensal Gram positive (+) bacteria conditioned media (CM) on tumour necrosis factor alpha (TNF-alpha) release is examined. An anti-THF-alpha effect is exerted in vitro by the commensal Gram positive bacteria and the probiotic bacteria Bifidobacterium breve and Streptococcus thermophilus.

The kinetics of a dairy probiotic Bifidobacterium strain called Bifidobacterium animalis DN-173 010 with different carbohydrates belonging to the insulin-type fructans was examined and the data about the degradation of the inulin-type fructans during the fermentation process was collected using gas chromatography. Bifidobacterium animalis DN-173 010 was responsible for preferentially metabolizing short fractions of oligofructose.

A study investigating the growth of Bifidobacterium in soy milk, using glucose and cysteine, is presented. Biotransformation of isoflavones in soy milk is studied.

Researchers describe a PCR technique based on the transaldolase gene in Bifidobacterium coupled with denaturing gradient gel electrophoresis that can distinguish between species. This is possible because bifidobacteria produce 14 or more different types of transaldolase. Because they produce different electrophoretic patterns, the transaldolase genes must have variable sequences.

Many bifidobacteria can adhere to starch granules, which could be used to microencapsulate the bacteria for use as probiotics. The adhesion appears to involve alpha-1,4-linked glucose sugars and is reduced by protease, pancreatin, and pH values of 3 or less.

Researchers have developed strain- and species-specific PCR primers to detect Bifidobacterium lactis in yogurt, infant formulas, and infant feces. This bacterium is a probiotic that is used in the food industry and an accurate test is necessary for quality control purposes and public health monitoring.

Researchers have produced galacto-oligosaccharides that differ from the commercial prebiotic product Oligomate 55 by using several species of Bifidobacterium to produce galacto-oligosaccharides from lactose. This will enhance their specificity when metabolized by colonic microorganisms.

Three beta-galactosidases from Bifidobacterium bifidum DSM20215 and one beta-galactosidase from B. infantis DSM20088 are all able to produce galactooligosaccharides from lactose even though they have very different amino acid sequences, molecular structure, and size. These bacteria are used as probiotics in food, and certain oligosaccharides can stimulate their growth.

A new study investigates the ability of bifidobacteria and lactic acid bacteria to grow when exposed to clover honey, sucrose and fructose.

Research into the binding of iron by probiotics is presented.

Commercial strains of Bifidobacterium spp in skim milk containing oligosaccharides and inulin were studied.

Oligofructose and inulin, selective fermentable chicory fructans, have been shown to stimulate the growth of bifidobacteria, which are regarded as beneficial strains in the colon. Studies were designed to evaluate inulin (Raftiline) and oligofructose (Raftilose) for their potential inhibitory properties against the development of colonic aberrant crypt foci (ACF) in rats. ACF are putative preneoplastic lesions from which adenomas and carcinomas may develop in the colon. The results of this study indicate that dietary administration of oligofructose and inulin inhibits the development of ACF in the colon, suggesting the potential colon tumor inhibitory properties of chicory fructans. The degree of ACF inhibition was more pronounced in animals given inulin than in those fed oligofructose. Because these prebiotics selectively stimulate the growth of bifidobacteria, omithine decarboxylase (ODC) activities, ras-p21 ontoprotein expressions and tumor inhibitory activity of lyophilized cultures of Bifidobacterium longum against chemically induced colon and mammary carcinogenesis and against colonic tumor cell proliferation were examined. Dietary administration of lyophilized cultures of B. longum strongly suppressed colon and mammary tumor development and tumor burden. Inhibition of colon carcinogenesis was associated with a decrease in colonic mucosal cell proliferation and activities of colonic mucosal and tumor omithine decarboxylase and ras-p21. Human clinical trials are likely to broaden our insight into the importance of the pre- and probiotics in health and disease. KEY WORDS: * colon cancer * oligofructose * inulin * Bifidobacterium longum

Evidence indicates that consumption of probiotic microorganisms such as bifidobacteria reduces the risk of colon cancer in animal models. Feeding certain fructans such as oligofructose and inulin, which are thought to selectively increase the growth of intestinal bifidobacteria (i.e., a prebiotic effect), also has been shown to reduce colon cancer risk. The objective of our study was twofold, i.e., to determine whether the combination of bifidobacteria and oligofructose would have an additive effect (i.e., synbiotic) in reducing colon cancer risk in rats, and to determine whether other oligosaccharides would also be effective as part of a synbiotic combination. The development of colonic preneoplastic lesions (aberrant crypts) was used as an index of colon cancer risk. In one series of experiments, rats were given the carcinogen 1,2-dimethylhydrazine (DMH) and administered one of the following treatments: skim milk (control), bifidobacteria (bifido), oligofructose (OF) or bifido + OF. Neither bifido nor OF alone significantly reduced aberrant crypt number. Bifido + OF reduced aberrant crypt number in five of six experiments, although the reduction was significant in only one. However, a paired comparison of the six experiments indicated a significant overall reduction in aberrant crypts by bifido + OF (P = 0.039). Soybean oligosaccharide (SBO) and wheat bran oligosaccharide (WBO) were also fed in combination with bifidobacteria. In two other experiments, SBO did not alter the number of aberrant crypts compared with the control, whereas WBO reduced aberrant crypt number in one experiment but not in another. Of OF, SBO and WBO, only SBO reduced the colonic mucosa proliferation compared with the control. These results suggest that the combination of bifidobacteria and oligofructose reduces colon cancer risk in carcinogen-treated rats, but the effect of other oligosaccharides is uncertain. KEY WORDS: * colon cancer * bifidobacteria * oligosaccharide * probiotics * rats * oligofructose

Recent studies have identified several beneficial attributes of inulin (I) and oligofructose (OF) in human health. However, most of the studies pertaining to the physiologic role of these compounds have been conducted at higher concentrations (8-40 g/d) as a source of dietary fiber. There is growing interest in using I and OF as a substrate for the selective growth of beneficial gastrointestinal bacteria such as the bifidobacteria. In vitro fermentation studies using fecal inoculums have shown that I and OF are utilized rapidly and completely by intestinal microflora and that the degree of polymerization of the substrate influenced its rate of disappearance. In these and other studies, I and OF were shown to be efficient substrates for the growth of most strains of bifidobacteria compared with glucose. In vivo studies have also shown that when human volunteers ingested I or OF, the number of fecal bifidobacteria increased. However, when results from the reported studies are combined and analyzed, a dose-response relationship in terms of log increases in the count of bifidobacteria cannot be demonstrated. Initial numbers of bifidobacteria in the feces, independent of the dose of the fructo-oligosaccharides, seem to influence the results. Future investigations should consider this relationship carefully. KEY WORDS: * prebiotics * bifidobacteria * intestinal microflora * oligofructose * chicory oligofructose

Bifidobacterium longum strains were grown at pH 5.5, 6.0, 6.5 and 7.0 and examined for survival and bile tolerance during frozen and refrigerated storage in milk. Initial freezing did not lead to cell number reduction. Three of the four strains showed effects for strain, pH and storage at 5 degrees C in milk. Bifidobacterium longum S9 was the most stable and did not lose bile resistance during refrigerated storage.

Byline: Ana M. P. Gomes (1), M. Luz P. C. Silva (1), F. X. Malcata (1) Keywords: Key wordsaBifidobacteria; Cheese; Accelerated ripening; Proteolysis; Lipolysis Abstract: aThe effects of ripening temperature, relative humidity and time on chemical and textural characteristics of a 'probiotic' goat's milk cheese were examined. The experimental layout followed a 2.sup.3 factorial design, with all possible combinations of 5aadegC and 10aadegC (ripening temperature), 85% and 95% (ripening relative humidity) and 1 day and 70 days (ripening time). All proteolytic indices measured (water-soluble nitrogen, trichloroacetic acid-soluble nitrogen and phosphotungstic acid-soluble nitrogen) were enhanced with increased ripening temperature to a greater extent than with increased ripening relative humidity the increase in phosphotungstic acid-soluble nitrogen was the most significant. Free fatty acid concentrations in cheeses were not influenced by ripening relative humidity but increased with ripening temperature and time. A higher ripening temperature and a lower relative humidity gave rise to firmer cheeses. Postulated empirical models have provided a good fit to the experimental data set generated such models were able to predict a decrease of 25 days in ripening time with no impairment of either proteolytic or lipolytic indices if a cheese were to be ripened at 10aadegC (rather than 5aadegC) and 95% relative humidity. Author Affiliation: (1) Escola Superior de Biotecnologia, Universidade Catolica Portuguesa, Rua Dr. Antonio Bernardino de Almeida, P-4200 Porto, Portugal, PT Article note: Received: 23 March 1998

Research was conducted to examine alginate encapsulated and free cell bifidobacteria survival in mayonnaise under refrigerated storage of ~ 5 degrees C. Another objective would be to analyze their influence on any microbiological changes and the quality of the mayonnaise. Results demonstrate that the addition of encapsulated bifidobacteria caused an improvement in the sensory characteristics of mayonnaise.