Different utilization of glucose and raffinose in Bifidobacterium breve and Bifidobacterium animalis.

Growth of 2 strains of Bifidobacterium breve and 4 strains of Bifidobacterium animalis was evaluated with glucose, raffinose or a mixture of glucose and raffinose as substrates. All strains of B. animalis and one strain of B. breve grew more slowly on glucose than on raffinose or the mixture of glucose and raffinose; one strain of B. breve grew more rapidly on the mixture of glucose and raffinose than on raffinose while 2 strains of B. animalis grew faster on raffinose than on the mixture of raffinose and glucose. Both strains of B. breve utilized glucose and raffinose simultaneously. In contrast, all strains of B. animalis strains displayed atypical growth with rapid utilization of raffinose followed by slow utilization of glucose. The cell morphology of all strains of B. animalis was affected by the sugar used for cultivation: tiny and rather spherical cells were observed on glucose while on media with raffinose the cells were large and had the species-specific shape. Description of preferential utilization of various saccharides by bifidobacteria can contribute to the development of new synbiotic preparations and new cultivation media for bifidobacteria.

Distribution of bifidobacteria in the gastrointestinal tract of calves.

Development of gastrointestinal microflora of calves with special reference to bifidobacteria was investigated; fecal bacteria were enumerated in calves aged 3 days to 7 weeks. Bacteria were detected by using selective media, bifidobacteria using modified TPY agar with an addition of mupirocin and acetic acid and by fluorescence in situ hybridization (FISH). Bifidobacteria were dominant group of fecal flora of calves after 7 d of life, constituting 10 % of total bacterial counts. The highest bacterial concentrations were observed in rumen, cecum, and colon, the lowest in abomasum and duodenum. Bifidobacteria and lactobacilli exhibited the highest survival ability during stomach passage and dominated in all parts of the digestive tract. Bifidobacteria counts determined by FISH were significantly higher than those provided by cultivation. Modified TPY agar was highly selective and suitable for bifidobacteria isolation but FISH was shown to be a more precise method for their enumeration. Our results show that gastrointestinal microflora of calves in the milk-feeding period is similar to breast-fed infants with respect to the occurrence of bifidobacteria as a dominant bacterial group. The use of Bifidobacterium strains offers a promising way for providing beneficial effectors for calves in the milk-feeding period.

Detection of infant faecal bifidobacteria by enzymatic methods.

An enzyme-based assay was developed for the detection of bifidobacteria in infant faeces. Ninety-five samples from 51 breast-fed infants in the age between 3 and 276 days were investigated. Bifidobacteria and other bacterial groups were determined by cultivation and fluorescence in situ hybridisation (FISH). Faecal samples were examined for the activity of fructoso-6-phosphate phosphoketolase (F6PPK) and for other enzymatic reactions using the API-ZYM kit. Twenty-nine infants had high numbers of bifidobacteria (usually higher than 9 log CFU/g) in their faeces. Seventeen infants (35%) did not contain detectable amounts of bifidobacteria in their faecal samples. The remaining five individuals had low counts of bifidobacteria (3-6 log CFU/g). Most negative infants possessed major amounts of clostridia in their faecal flora. There were no significant differences among bifidobacterial counts obtained by cultivation and FISH, detection of F6PPK, alpha-galactosidase and alpha-glucosidase activities could routinely be used for the rapid and simple detection of bifidobacteria in infant faecal samples. Bifidobacterial colonies were identified using enzymatic tests and PCR procedure based on 16S rRNA gene sequences species-specific primers. In 14 samples, the identifications of individual isolates were compared with direct analyses of faeces using the nested PCR-denaturing gradient gel electrophoresis (nested DGGE) procedure. The results obtained in several cases are not identical. Bifidobacterium longum and Bifidobacterium breve were most frequently identified. Bifidobacteria-positive samples had high activities of alpha-galactosidase and alpha-glucosidase. On the contrary, negative samples missed either one or both of these enzymatic activities. While all positive samples tested showed distinctive fructose-6-phosphate phosphoketolase activity (F6PPK), none of the negative samples expressed F6PPK activity.

The bifidogenic effect of Taraxacum officinale root.

The infusion of dandelion root (Taraxacum officinale) stimulated in vitro the growth of 14 strains of bifidobacteria. The utilization of oligofructans, glucose, fructose and total saccharides was determined by enzymatic and phenol-sulfuric methods. Dandelion oligofructans were important source of carbon and energy for bifidobacteria tested.