Synthesis and utilisation of folate by yoghurt starter cultures and probiotic bacteria.

Thirty-two bacterial isolates from species commonly used in yoghurts and fermented milks were examined for their ability to synthesise or utilise folate during fermentation of skim milk. The organisms examined included the traditional yoghurt starter cultures, Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus, and probiotic lactobacilli, bifidobacteria, and Enterococcus faecium. Folate was synthesised by S. thermophilus, bifidobacteria, and E. faecium. S. thermophilus was the dominant producer, elevating folate levels in skim milk from 11.5 ng g(-1) to between 40 and 50 ng g(-1). Generally, lactobacilli depleted the available folate in the skim milk. Fermentations with mixed cultures showed that folate production and utilisation by the cultures was additive. Fermentations using a combination of Bifidobacterium animalis and S. thermophilus resulted in a six-fold increase in folate concentration. Although increased folate levels in yoghurts and fermented milks are possible through judicious selection of inoculum species, the folate levels remain relatively low in terms of recommended daily allowance.

Purification of food-grade oligosaccharides using immobilised cells of Zymomonas mobilis.

Immobilised cells of the bacterium Zymomonas mobilis were used to remove glucose, fructose, and sucrose from food-grade oligosaccharide mixtures. Unpurified fructo-, malto-, isomalto-, gentio-, and inulinoligosaccharides, containing total carbohydrate concentrations of 300 g l(-1), were added to immobilised cells, in 100 ml batch reactors. No pH control or nutrient additions were required. Contaminating glucose, fructose, and sucrose within the mixtures was completely fermented within 12 h. The fermentation end products were ethanol and carbon dioxide. A minor amount of sorbitol was also produced as a fermentation by-product in the inulin-oligosaccharide mixture. No degradation of the oligosaccharides in the mixtures was observed.

Cross correlation of the cosmic microwave background with radio sources: constraints on an accelerating universe.

We present a new limit on the cosmological constant based on the absence of correlations between the cosmic microwave background (CMB) and the distribution of distant radio sources. In cosmological constant, cold dark matter ( LambdaCDM) models, such correlations should have been produced via the integrated Sachs-Wolfe effect, assuming that radio sources trace the local ( z approximately 1) matter density. We find no evidence of correlations and obtain a 95% C.L. upper limit on the cosmological constant of Omega(Lambda)< or =0.74. If 0.6

Selection of a Bifidobacterium strain to complement resistant starch in a synbiotic yoghurt.

AIMS: To employ an in vitro screening regime to select a probiotic Bifidobacterium strain to complement resistant starch (Hi-maizetrade mark) in a synbiotic yoghurt. METHODS AND RESULTS: Of 40 Bifidobacterium isolates examined, only B. lactis Laftitrade mark B94 possessed all of the required characteristics. This isolate hydrolysed Hi-maizetrade mark, survived well in conditions simulating passage through the gastrointestinal tract and possessed technological properties suitable for yoghurt manufacture. It grew well at temperatures up to 45 degrees C, and grew to a high cell yield in an industrial growth medium. In addition to resistant starch, the organism was able to utilize a range of prebiotics including inulin, and fructo-, galacto-, soybean- and xylo-oligosaccharides. Pulse field gel electrophoresis of restriction enzyme cut chromosomal DNA revealed that B. lactis Laftitrade mark B94 was very closely related to the B. lactis Type Strain (DSM 10140), and to the commercial strains B. lactis Bb-12 and B. lactis DS 920. However, B. lactis Laftitrade mark B94 was the only one of these isolates that could hydrolyse Hi-maizetrade mark. This phenotypic difference did not appear to be due to the presence of plasmid encoded amylase. Bifidobacterium lactis Laftitrade mark B94 survived without substantial loss of viability in synbiotic yoghurt containing Hi-maizetrade mark during storage at 4 degrees C for six weeks. CONCLUSION: Bifidobacterium lactis Laftitrade mark B94 is a promising new yoghurt culture that warrants further investigation to assess its probiotic potential. SIGNIFICANCE AND IMPACT OF THE STUDY: In vitro screening procedures can be used to integrate complementary probiotic and prebiotic ingredients for new synbiotic functional food products.

In vitro adhesion and platelet aggregation properties of bacteremia-associated lactobacilli.

Eight bacteremia-associated Lactobacillus strains were evaluated in vitro for the ability to adhere to human intestinal mucosa and to aggregate platelets. Adherence varied significantly among the strains, and platelet aggregation was induced by three strains. In conclusion, strong binding ability does not appear to be a prerequisite for the involvement of lactobacilli in bacteremia or to their ability to aggregate platelets.