Preterm germ-free piglets were monoassociated with probiotic Bifidobacterium animalis subsp. lactis BB-12 (BB12) to verify its safety and to investigate possible protection against subsequent infection with Salmonella Typhimurium strain LT2 (LT2). Clinical signs of salmonellosis, bacterial colonization in the intestine, bacterial translocation to mesenteric lymph nodes (MLN), blood, liver, spleen, and lungs, histopathological changes in the ileum, claudin-1 and occludin mRNA expression in the ileum and colon, intestinal and plasma concentrations of IL-8, TNF-α, and IL-10 were evaluated. Both BB12 and LT2 colonized the intestine of the monoassociated piglets. BB12 did not translocate in the BB12-monoassociated piglets. BB12 was detected in some cases in the MLN of piglets, consequently infected with LT2, but reduced LT2 counts in the ileum and liver of these piglets. LT2 damaged the luminal structure of the ileum, but a previous association with BB12 mildly alleviated these changes. LT2 infection upregulated claudin-1 mRNA in the ileum and colon and downregulated occludin mRNA in the colon. Infection with LT2 increased levels of IL-8, TNF-α, and IL-10 in the intestine and plasma, and BB12 mildly downregulated them compared to LT2 alone. Despite reductions in bacterial translocation and inflammatory cytokines, clinical signs of LT2 infection were not significantly affected by the probiotic BB12. Thus, we hypothesize that multistrain bacterial colonization of preterm gnotobiotic piglets may be needed to enhance the protective effect against the infection with S. Typhimurium LT2.

• Keywords
• Bifidobacterium animalis subsp. lactis BB-12, Salmonella Typhimurium, immunocompromised, inflammatory cytokines, intestinal barrier, preterm host,
• Publication type
• Journal Article MeSH

The family Bifidobacteriaceae constitutes an important phylogenetic group that particularly includes bifidobacterial taxa demonstrating proven or debated positive effects on host health. The increasingly widespread application of probiotic cultures in the twenty-first century requires detailed classification to the level of particular strains. This study aimed to apply the glutamine synthetase class I (glnAI) gene region (717 bp representing approximately 50% of the entire gene sequence) using specific PCR primers for the classification, typing, and phylogenetic analysis of bifidobacteria and closely related scardovial genera. In the family Bifidobacteriaceae, this is the first report on the use of this gene for such purposes. To achieve high-value results, almost all valid Bifidobacteriaceae type strains (75) and 15 strains isolated from various environments were evaluated. The threshold value of the glnAI gene identity among Bifidobacterium species (86.9%) was comparable to that of other phylogenetic/identification markers proposed for bifidobacteria and was much lower compared to the 16S rRNA gene. Further statistical and phylogenetic analyses suggest that the glnAI gene can be applied as a novel genetic marker in the classification, genotyping, and phylogenetic analysis of isolates belonging to the family Bifidobacteriaceae.

• MeSH
• Genes, Bacterial MeSH
• Bifidobacterium classification   enzymology   MeSH
• DNA, Bacterial genetics   MeSH
• DNA Primers MeSH
• Phylogeny * MeSH
• Genetic Markers MeSH
• Genotype MeSH
• Glutamate-Ammonia Ligase genetics   MeSH
• RNA, Ribosomal, 16S genetics   MeSH
• Sequence Analysis, DNA MeSH
• Bacterial Typing Techniques MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• DNA, Bacterial MeSH
• DNA Primers MeSH
• Genetic Markers MeSH
• glutamine synthetase I MeSH Browser
• Glutamate-Ammonia Ligase MeSH
• RNA, Ribosomal, 16S MeSH

An alternative molecular marker with respect to the 16S rRNA gene demonstrating better identification and phylogenetic parameters has not been designed for the whole Bifidobacteriaceae family, which includes the genus Bifidobacterium and scardovial genera. Therefore, the aim of the study was to find such a gene in available genomic sequences, suggest appropriate means and conditions for asmplification and sequencing of the desired region of the selected gene in various strains of the bacterial family and verify the importance in classification and phylogeny. Specific primers flanking the variable region (~800 pb) within the pyrG gene encoding the CTP synthetase were designed by means of gene sequences retrieved from the genomes of strains belonging to the family Bifidobacteriaceae. The functionality and specificity of the primers were subsequently tested on the wild (7) and type strains of bifidobacteria (36) and scardovia (7). Comparative and phylogenetic studies based on obtained sequences revealed actual significance in classification and phylogeny of the Bifidobacteriaceae family. Gene statistics (percentages of mean sequence similarities and identical sites, mean number of nucleotide differences, P- and K-distances) and phylogenetic analyses (congruence between tree topologies, percentages of bootstrap values >50 and 70%) indicate that the pyrG gene represents an alternative identification and phylogenetic marker exhibiting higher discriminatory power among strains, (sub)species, and genera than the 16S rRNA gene. Sequences of the particular gene fragment, simply achieved through specific primers, enable more precisely to classify and evaluate phylogeny of the family Bifidobacteriaceae including, with some exceptions, health-promoting probiotic bacteria.

• Keywords
• Bifidobacteriaceae, Bifidobacterium, CTP synthetase, classification, phylogenetics, scardovia,
• MeSH
• Actinobacteria classification   enzymology   genetics   isolation & purification   MeSH
• Bacterial Proteins chemistry   genetics   metabolism   MeSH
• DNA, Bacterial genetics   MeSH
• DNA Primers genetics   MeSH
• Phylogeny * MeSH
• Carbon-Nitrogen Ligases chemistry   genetics   metabolism   MeSH
• RNA, Ribosomal, 16S genetics   MeSH
• Bacterial Typing Techniques methods   MeSH
• Publication type
• Journal Article MeSH
• Evaluation Study MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Bacterial Proteins MeSH
• CTP synthetase MeSH Browser
• DNA, Bacterial MeSH
• DNA Primers MeSH
• Carbon-Nitrogen Ligases MeSH
• RNA, Ribosomal, 16S MeSH