Bifidobacterium Longum Strains Research Articles

Improvement of Lactose Digestion in Humans by Ingestion of Unfermented Milk Containing Bifidobacterium longum

Fifteen lactose malabsorbers were studied to evaluate the effects of consumption of milk containing different strains of Bifidobacterium longum on lactose digestion. Influences of different growth substrates, bile sensitivity, and lactose transport on lactose digestion by bifidobacteria were also investigated. Lactose malabsorption was determined by measuring breath hydrogen excretion of subjects fed four different test milks (three of which contained 5 × 108 cfu/ml of B. longum) on 4 different d using a randomized, double-blinded trial. Test milks included 1) 400ml of lowfat milk (control), 2) 400ml of milk containing B. longum B6 that had been grown with lactose, 3) 400ml of milk containing B. longum B6 grown with lactose plus glucose, or 4) 400ml of milk containing B. longum ATCC 15708 grown with lactose. β-Galactosidase activity was highest in milk containing B6 grown with lactose but was extremely low in milk containing B6 grown with lactose and glucose. Consumption of milk containing B6 grown with lactose resulted in significantly less hydrogen production and flatulence than occurring after consumption of control milk or the milk containing B6 grown with both lactose and glucose. Hydrogen production after ingestion of 15708 was also significantly lower than hydrogen production after ingestion of the control milk. We concluded that milks containing B. longum might reduce breath hydrogen response and symptoms from lactose malabsorption when the culture is grown in a medium containing only lactose to induce a higher β-galactosidase level and increase rate of lactose uptake.

Characterisation of a complex restriction/modification system detected in a Bifidobacterium longum strain

Two type-II restriction endonucleases, BloI and BloII, have been detected in a Bifidobacterium longum strain. BloI is influenced by dam methylation: it cleaves dam − but not dam + DNA. It shows a temperature and pH optimum of 45°C and pH 7.5. Restriction analysis and cloning experiments showed that the recognition sequence is RGATCY and that the enzyme cuts 5′ to the guanine residue. It is an isoschizomer of commercial enzymes, Bst YI and XhoII. The second activity is not inhibited by dam methylation. It has a temperature optimum between 25°C and 30°C and shows a broad pH optimum between 4.5 and 7.0. The activity is thermolabile and can be heat-killed by a 5 min incubation at 60°C. Cloning and sequencing experiments revealed that its recognition sequence is CTGCAG and that it cuts 5′ to the second guanine residue in the sequence. This enzyme is the first described isoschizomer of PstI.

Bifidobacteria and probiotic effects: action of Bifidobacterium species on conjugated bile salts.

The effect of six different conjugated bile salts (two trihydroxyconjugated bile salts: tauro and glycocholic acids; and four dihydroxyconjugated bile salts: tauro- and glycochenodeoxycholic, tauro- and glycodeoxycholic acids) on eight bifidobacteria strains were studied. A strong growth-inhibitory effect was observed (80% at 0.95 mM) for each bile salt and strain. This phenomenon was explained by the production of deconjugated bile salt during bifidobacteria growth. The deconjugation phenomenon was concurrent with biomass production, and deconjugated bile salts were the sole compound produced during bifidobacteria biotransformation. In resting cell experiments, differences appeared between the strains and the kind of bile salts, particularly concerning taurocholic acid. The Bifidobacterium longum strains were the most efficient among the bacteria tested.

Suppressive Effects of the Methanol Extracts from Soybean Products on SOS Response of Salmonella typhimurium Induced by Mutagens and Their Contents of Isoflavones.

The suppressive effects on SOS response of Salmonella typhimurium TA 1535/pSK 1002 induced by MNNG and Trp-P-1 of the methanol extracts prepared from soybeans and soy products were investigated. The content of isoflavones in the extract was also determined. The extracts of soybean and soymilk scarcely suppressed SOS response by mutagens. The suppression by the extracts of fermented product was stronger than that by the unfermented products. However, the percentage suppression in the extracts of natto and soy sauce was similar to that in the unfermented products. The extracts of tempeh and miso having strong suppression contained much daidzein and genistein. On the other hand, the extracts of unfermented product and such fermented product as natto and soy sauce having weak suppression contained much isoflavone glycoside. The percentage suppression of the extracts from soymilks fermented by a strain of Lactobacillus bulgaricus or Streptococcus thermophilus was lower than that by a strain of Bifidobacterium longum or a mixture of three strains.

Quantitative Fluorometric Assay for Rapid Enzymatic Characterization of Bifidobacterium longum and Related Bifidobacteria

The quantitative, semi-automated assay described here is an alternative characterization method allowing for highly sensitive and specific detection of bifidobacterial enzymes. Twenty strains of Bifidobacterium longum, including the type strain ATCC 15707, and type strains of 15 other Bifidobacterium species were enzymatically characterized using 20 4-methylumbelliferyl conjugated substrates. Enzyme activities were determined by directly measuring the intensity of fluorescence derived from 4-methylumbelliferone, a fluorescent metabolic by-product. For this method, a Titertek Fluoroskan II fluorometer was used. Enzymes included glycosidases, an esterase, phosphatase, sulphatase, and neuraminidase. B. longum showed strong activity (greater than 1,000 absolute fluorescence units, afu) for alpha-L-Arabinopyranosidase and alpha-L-Arabinofuranosidase, beta-D-Fucosidase, alpha- and beta-D-Galactosidase, alpha-D-Glucosidase, and alpha-D-Mannosidase. No activity (less than or equal to 50 afu) was observed for beta-D-Cellobiosidase, alpha- and beta-L-Fucosidase, beta-D-Glucuronidase, beta-D-Mannosidase, Neuraminidase and Sulphatase. Enzymatic activity profiles in other bifidobacteria were different according to the species. This assay is simple and rapid (6 hr). Special cultural requirements are unnecessary. Results are objective and quantitative. This assay may be a useful tool for bifidobacterial taxonomy.

Detection ofBifidobacteriurn longumin faecal samples after orogastric intubation using immunological test systems

A simple method based on a sandwich-ELISA was developed to study the passage and the viability of a bifidobacterial species after oral application of lyophilized preparation. Rabbits were immunized with a formaldehyde-inactivated strain of the species Bifidobacterium longum resulting in a highly specific antiserum. The cross-reaction of most of 46 selected, representative strains of 14 bifidobacterial species from animal and human sources was negligibly low. Only two strains of B. angulatum and some strains of B. longum isolated from breast-fed infants showed cross-reactions greater than 10 per cent, which was not reflected by biochemical characteristics such as murein type and DNA-DNA homology grouping. Western blot analyses indicated a 60-KDa protein as the major immunogen of the strain used for the immunization procedure. The detection limit of the sandwich-ELISA developed on the basis of the antiserum was about 10 3 cells/ml test buffer. Viable B. longum could be detected strain specifically in faeces of minipigs after oral application of a pharmaceutical product containing B. longum and two additional non-bifidobacterial species. The viable B. longum was determined by a combination of selective cultivation from faecal samples and immunological techniques based on the specific anti- B. longum antibody. Keywords: Bifidobacterium longum ; Sandwich-ELISA; Immunoblot; Western blot; Cross-reaction.

Differential Characteristics of Bifidobacterium longum and Bifidobacterium animalis

Twenty five strains, which belong to Bifidobacterium animalis on the basis of their carbohydrate fermentation patterns, were isolated from human and calf feces. The DNAs of these strains were, however, completely homologous to the DNA of the type strain of Bifidobacterium longum . In this study, the phenotypic characteristics for differentiating B. longum from B. animalis were investigated. B. longum showed mostly very elongated and relatively thin cells with slightly irregular contours, while B. animalis consisted of relatively short rods with a slightly enlarged central portion. Strains of B. longum failed to grow in the presence of 4.2% NaCl at 37°C or 3.0% NaCl at 45 °C, and possessed N-acetyl-β-glucosaminidase, while B. animalis strains grew in either culture condition, possessed β-glucosidase and phosphoamidase, but not N-acetyl-β-glucosaminidase.