Functional, bioactive, biochemical, and physicochemical properties of the Dolichos lablab bean.

The underutilized Kenyan variety of Dolichos lablab bean seeds serves as a good source of nutrients. This study was undertaken for the first time to address the limited knowledge regarding the bioactive, biochemical, physicochemical, and functional properties of Dolichos lablab beans. Proximate analysis, mineral, total and free amino acid profiles, total protein, total dietary and profile of fiber, carotenoids and fat soluble vitamins, total phenolics, and total flavonoids were evaluated. The results clearly show that Dolichos lablab beans contain many health-promoting components, such as fiber, proteins, minerals, and numerous phytochemicals endowed with useful biological activities, that allow it to contribute in a relevant way to the daily intake of these nutrients.

Classification of a moderately oxygen-tolerant isolate from baby faeces as Bifidobacterium thermophilum.

BACKGROUND: Bifidobacteria are found at varying prevalence in human microbiota and seem to play an important role in the human gastrointestinal tract (GIT). Bifidobacteria are highly adapted to the human GIT which is reflected in the genome sequence of a Bifidobacterim longum isolate. The competitiveness against other bacteria is not fully understood yet but may be related to the production of antimicrobial compounds such as bacteriocins. In a previous study, 34 Bifidobacterium isolates have been isolated from baby faeces among which six showed proteinaceous antilisterial activity against Listeria monocytogenes. In this study, one of these isolates, RBL67, was further identified and characterized. RESULTS: Bifidobacterium isolate RBL67 was classified and characterized using a polyphasic approach. RBL67 was classified as Bifidobacterium thermophilum based on phenotypic and DNA-DNA hybridization characteristics, although 16S rDNA analyses and partial groEL sequences showed higher homology with B. thermacidophilum subsp. porcinum and B. thermacidophilum subsp. thermacidophilum, respectively. RBL67 was moderately oxygen-tolerant and was able to grow at pH 4 and at a temperature of 47 degrees C. CONCLUSION: In order to assign RBL67 to a species, a polyphasic approach was used. This resulted in the classification of RBL67 as a Bifidobacterium thermophilum strain. To our knowledge, this is the first report about B. thermophilum isolated from baby faeces since the B. thermophilum strains were related to ruminants and swine faeces before. B. thermophilum was previously only isolated from animal sources and was therefore suggested to be used as differential species between animal and human contamination. Our findings may disapprove this suggestion and further studies are now conducted to determine whether B. thermophilum is distributed broader in human faeces. Furthermore, the postulated differentiation between human and animal strains by growth above 45 degrees C is no longer valid since B. thermophilum is able to grow at 47 degrees C. In our study, 16S rDNA and partial groEL sequence analysis were not able to clearly assign RBL67 to a species and were contradictory. Our study suggests that partial groEL sequences may not be reliable as a single tool for species differentiation.

Effect of Bifidobacterium thermacidophilum probiotic feeding on enterohemorrhagic Escherichia coli O157:H7 infection in BALB/c mice.

The effectiveness of Bifidobacterium thermacidophilum RBL 71 as a probiotic against enterohemorrhagic Escherichia coli O157:H7 infection was studied using a murine model. BALB/c mice were fed the probiotic for 7 days before or after single challenge with E. coli O157:H7. Fecal B. thermacidophilum RBL 71 and E. coli O157:H7 counts obtained by selective culturing methods were assessed for 1 week before and after infection while feed intake, body weight and composition were monitored during 1 week after infection. Histology of gut tissue (jejunum, ileum and colon) and production of fecal IgA antibodies and serum IgG+IgM antibodies to E. coli O157:H7 were analyzed until 1 and 2 weeks post-infection, respectively. The pathogenicity of E. coli O157:H7, marked by body weight loss and intestinal histopathological changes in the infected group, was significantly reduced in the B. thermacidophilum-treated group. Feeding B. thermacidophilum RBL 71 for 7 days before infection resulted in greater post-challenge feed intake and weight gain and lower fecal levels of E. coli O157:H7. Post-infection levels of anti-E. coli O157:H7-specific IgA in feces and IgG+IgM in serum were higher in mice fed bifidobacteria. Intestinal injuries were also attenuated and reaction of the lymphoid component in the mucosa of the ileum was greater in the bifidobacteria-fed group. A lesser degree of protection against E. coli O157:H7 infection was observed when bifidobacteria were given during the 7 days after E. coli O157:H7 infection. These results demonstrate that feeding the probiotic B. thermacidophilum RBL 71 to mice can reduce the severity of E. coli O157:H7 infection, and suggest that this strain represents a good candidate for the prevention of enteric infections in human.

In vitro inhibition of Escherichia coli O157:H7 by bifidobacterial strains of human origin.

The ability of bifidobacteria isolated from infant feces to inhibit enterohemorrhagic Escherichia coli serotype O157:H7 in vitro and reduce its adhesion to human enterocyte-like Caco-2 cells was evaluated in comparison to American Type Culture Collection bifidobacterial reference strains. Five Bifidobacterium isolates from infant feces were identified and characterized by morphology, fructose-6-phosphate phosphoketolase (F6PPK) assay, polymerase chain reaction using bifidobacterial 16S rDNA specific primers, carbohydrate fermentation patterns, resistance to lysozyme, acid, bile and hydrogen peroxide as well as their ability to inhibit E. coli O157:H7 using the agar spot technique. Infant isolates showed greater resistance to bile, acid, lysozyme and more antimicrobial activity against E. coli O157:H7 than ATCC strains. Two infant isolates identified as B. bifidum RBL 71 and B. bifidum RBL 460 showed good adhesion and significant potential for reducing adhesion of E. coli O157:H7 to Caco-2 cells. This effect was dependent on bifidobacterial cell concentration. These results show that bifidobacteria isolated from infants may be useful for improving probiotic formulae with respect to protection against E. coli O157:H7 infection.