Characterization of a Bifidobacterium animalis subsp. lactis reference strain based on ecology and transcriptomics.

2024-10-23
Applied and environmental microbiology 90(10)

PubMed: 39235395
DOI: 10.1128/aem.01080-24

Study Design

Methods: dissected the genetic repertoire and phylogenetic relationship of 162 strains of B. animalis subsp. lactis to select a representative reference strain; the B. animalis subsp. lactis PRL2013 strain, isolated from a mucosal sample of a healthy adult, was exposed to human cell monolayers and analyzed by transcriptomics

Rigorous Journal

Bifidobacteria are recognized as health-promoting bacteria that reside in the human gut, helping in the digestion of fiber, preventing infections, and producing essential compounds like vitamins. To date, Bifidobacterium animalis subsp. lactis, together with Bifidobacterium adolescentis, Bifidobacterium bifidum, Bifidobacterium breve, and Bifidobacterium longum, represents one of the species that are used as probiotic bacteria. Despite the extensive and detailed scientific research conducted on this microbial taxon, the molecular mechanisms by which B. animalis subsp. lactis exerts health benefits to its host are still largely unknown. Thus, we dissected the genetic repertoire and phylogenetic relationship of 162 strains of B. animalis subsp. lactis to select a representative reference strain of this taxon suitable for investigating its interaction with the host. The B. animalis subsp. lactis PRL2013 strain, which was isolated by a mucosal sample of a healthy adult, was chosen as the reference of the monophyletic cluster of human origin and revealed a greater adhesion index than that observed for another B. animalis subsp. lactis strain used in the industry as a probiotic supplement. Transcriptomics analyses of PRL2013 strain, when exposed to human cell monolayers, revealed 291 significantly upregulated genes, among which were found genes predicted to encode extracellular structures that may directly interact with human cells, such as extracellular polymeric substances, wall teichoic acids, and pili.

Importance

To date, many Bifidobacterium animalis subsp. lactis strains have been isolated from human fecal samples. However, their presence in these samples does not necessarily suggest an ability to colonize the human gut. Furthermore, probiotics of non-human origin may not effectively interact with the gut epithelium, resulting in transient bacteria of the gut microbiota. In vitro experiments with human cells revealed that B. animalis subsp. lactis PRL2013, an autochthonous member of the human gut, shows colonization capability, leading to future applications in functional foods.

Research Insights

Supplement	Dose	Health Outcome	Effect Type	Effect Size	Source
Bifidobacterium animalis subsp. lactis BB-12	—	Improved Niche Colonization	Beneficial	Moderate	View source B. animalis subsp. lactis PRL2013... was chosen as the reference of the monophyletic cluster of human origin and revealed a greater adhesion index... Transcriptomics analyses... revealed 291 significantly upregulated genes... predicted to encode extracellular structures that may directly interact with human cells.