Effect of production conditions on the stability of a human bifidobacterial species Bifidobacterium longum in yogurt

Aims:  Human bifidobacteria are more sensitive to external environmental factors than animal bifidobacteria, and it is difficult to ensure their stable survival in yogurt. The purpose of this investigation was to observe the survival of human bifidobacteria in yogurts produced under various production conditions.
Methods:  Frozen or lyophilized bifidobacteria starters containing Bifidobacterium longum BB536 originally isolated from an infant, and commercial lyophilized yogurt starters were used for yogurt preparation. After producing yogurts under various conditions, the survival of bifidobacteria in these yogurts over various storage periods was observed.
Results:  Although there were some differences in bifidobacterial survival in yogurt between various production conditions, more than 1·0 × 10⁷ CFU g⁻¹ of Bif. longum survived in yogurt after 35 days' storage at 5°C. Lower fermentation temperature (37°C) and inclusion of Lactococcus lactis in the starter significantly ( P  < 0·05) improved survival of Bif. longum in the yogurt.
Conclusion:  In this investigation, the human bifidobacterial strain Bif. longum survived adequately in yogurt, although the fermentation temperature and starter composition affect bifidobacterial survival.
Significance and Impact of the Study:  This investigation indicates that stable probiotic yogurt using human bifidobacteria can be produced by choosing optimal production conditions.     

Bifidobacterium breve M-16V alters the gut microbiota to alleviate OVA-induced food allergy through IL-33/ST2 signal pathway

There has been a marked increase in life-threatening food allergy (FA). One hypothesis is that changes in bacterial communities may be key to FA. To better understand how gut microbiota regulates FA in humans, we established a mouse model with FA induced by ovalbumin. We found that the mice with FA had abnormal bacterial composition, accompanied by increased immunoglobulin G, immunoglobulin E, and interleukin-4/interferon-γ, and there existed a certain coherence between them. Interestingly, Bifidobacterium breve M-16V may alter the gut microbiota to alleviate the allergy symptoms by IL-33/ST2 signaling. Our results indicate that gut microbiota is essential for regulating FA to dietary antigens and demonstrate that intervention in bacterial community regulation may be therapeutically related to FA.     

Cloning and characterization of a novel α-galactosidase from Bifidobacterium breve 203 capable of synthesizing Gal-α-1,4 linkage

A novel α-galactosidase gene ( aga2 ) was cloned from Bifidobacterium breve 203. It contained an ORF of 2226-bp nucleotides encoding 741 amino acids with a calculated molecular mass of 81.5 kDa. The recombinant enzyme Aga2 was heterogeneously expressed, purified and characterized. Regarding substrate specificity for hydrolysis, Aga2 was highly active towards p -nitrophenyl-α- d -galactopyranoside ( p NPG). The K _m value for p NPG was estimated to be 0.27 mM and for melibiose it was estimated to be 4.3 mM. Aga2 was capable of catalyzing transglycosylation as well as hydrolysis. The enzyme synthesized a trisaccharide (Gal-α-1, 4-Gal-α-1, 6-Glc) using melibiose as a substrate. It was a new oligosaccharide produced by glycosidase and contained Gal-α-1,4 linkage, a novel galactosidic link formed by microbial α-galactosidase. In the presence of p NPG as a donor, Aga2 was able to catalyze glycosyl transfer to various acceptors including monosaccharides, disaccharides and sugar alcohols.     

Analysis of the genome of the five Bifidobacterium breve strains: plasmid content, pulsed-field gel electrophoresis genome size estimation and rrn loci number

Abstract The genomes of the five Bifidobacterium breve strains available from culture collections were compared by restriction endonuclease analysis. Electrophoretic migration of undigested DNA allowed us to detect a 5.6-kb circular plasmid in two of these strains. A restriction map of this plasmid was constructed using 10 enzymes. With Dra I endonuclease, pulsed-field gel electrophoresis has allowed the determination of the five B. breve genome sizes to 2.1 Mb. This estimation was further confirmed for CIP 6469 (type strain) and ATCC 15698 using Xba I and Spe I enzymes. In addition, rRNA gene regions were used as probes for strain characterization and suggest that there are at least three rrn loci in B. breve .