Abstract
Bifidobacteria are one of the major components in human gut microbiota and well-known as beneficial microbes. However, clarification of commensal mechanisms of bifidobacteria in the intestines is still ongoing, especially in the presence of the gut microbiota. Here, we applied recombinase-based in vivo expression technology (R-IVET) using the bacteriophage P1 Cre/loxP system to Bifidobacterium longum subsp. longum 105-A (B. longum 105-A) to identify genes that are specifically expressed in the gastrointestinal tract of conventionally raised mice. Oral administration of the genomic DNA library of B. longum 105-A to conventionally raised mice resulted in the identification of 73 in vivo-induced genes. Four out of seven tested genes were verified in vivo-specific induction at least in the cecum by quantitative reverse transcription PCR. Although there is still room for improvement of the system, our findings can contribute to expanding our understanding of the commensal behavior of B. longum in the gut ecosystem.
Highlights
Bifidobacteria are one of the major components in the gut microbiota of humans, especially infants [1,2,3]
These results indicated that the Sp resistance (SpR) gene was stably maintained in the chromosome of B. longum 105-A
They are not appropriately comparable because different Bifidobacterium species/strains were used in these studies, the observed difference in the gene datasets appears to be partially attributed to the distinct principles of recombinase-based in vivo expression technology (R-IVET) and DNA microarray approaches
Summary
Bifidobacteria are one of the major components in the gut microbiota of humans, especially infants [1,2,3]. More than 10 species of Bifidobacterium are known to colonize the human gut [4]. The occurrence of each in the gut differs depending on the species [5]. Longum (B. longum) is one of the most representative human gut-associated bifidobacteria. A recent study has reported that B. longum is the most ubiquitously and highly distributed among bifidobacteria across the human lifespan [6]. B. longum is prevalent across various mammalian species [7]. Certain strains of B. longum are reported to provide hosts with health benefits [8,9]
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