๐ก The human gut microbiota undergoes dynamic changes across the life span, influencing host health. In this study, a comprehensive pooled analysis of 6,653 fecal samples, integrating data from 79 studies and the Parma Microbiota project, elucidated the taxonomic and functional fluctuations of the gut microbiota from infancy to old age.
Geographical origin analysis indicated continent-specific microbial profiles, reflecting dietary and lifestyle influences. This exploratory analysis suggested a stable temporal pattern in microbiome functionality and composition across different age groups.
Key Scientific Findings:
Intra-individual Variability Across Human Life:
- A metagenomic data set search retrieved data from 79 publicly available studies and 467 samples from the Parma Microbiota project, resulting in 6,653 healthy fecal samples.
- Shallow shotgun metagenomic analysis optimized taxonomic profiling, revealing 424,267,507 classified reads.
- Biodiversity assessment categorized samples into four age groups (G1-G4), with a significant increase in bacterial species abundance from infancy to childhood/adolescence and subsequent stability in adulthood and the elderly.
- Subdivision of age groups highlighted a significant increase in species number from G1c (6 monthsโ1 year) to G2a (5โ10 years), reaching stability thereafter (pairwise Kruskal-Wallis test P > 0.05).
Inter-individual Variability Between Different Stages of Life:
- Principal coordinate analysis (PCoA) based on Bray-Curtis dissimilarity matrix revealed a clear division between age groups.
- Pairwise PERMANOVA analysis indicated significant differences in microbiota structure among age groups, emphasizing the distinct composition of the G1 group.
- Fitting analyses identified Bifidobacterium longum as a key species negatively correlated with increasing age, while clusters of species positively correlated with age formed enterotypes reflecting the complexity of adult microbiota.
- Impact of variables related to BioProject and geographical origin on microbiota composition revealed statistically significant but modest effects.
Identification of Specific Bacterial Patterns Related to Different Human Stages of Life:
- Taxonomical profiling at the species level identified age-specific core microbiota and accessory taxa.
- G1 group displayed a simpler core microbiota, mainly represented by B. longum and Escherichia coli, while G2, G3, and G4 groups exhibited larger and more diversified cores.
- A screening process identified 29 bacterial species common to both core and accessory microbiota across all age groups, emphasizing their role as key representatives of the human gut microbiota.
- Rearrangement of taxa relative abundances over time indicated a dynamic co-existence and potential formation of a complex microbial ecosystem reaching climax conditions.
Intra-individual Variability Across Human Life:
- Age-specific core microbiota of G1 group included seven species, transitioning to larger and more diversified cores in G2, G3, and G4 groups.
- Accessory taxa showed a similar trend, supporting the hypothesis of compositional variability during early development and taxonomic stability in later life stages.
- Selection of mainly representative species common to core and accessory microbiota across all age groups revealed 29 key bacterial species, including B. uniformis and B. fragilis, highlighting their importance in the human gut microbiota.
The study provides a comprehensive understanding of the dynamic nature of the human gut microbiota, emphasizing age-related changes, functional adaptations, and influences of geographical origin. These findings underscore the importance of considering both taxonomic and functional aspects in elucidating the microbiome’s role in human health across the life span. Future research should address current limitations, allowing for a more nuanced exploration of the intricate interplay between gut microbiota and various factors influencing host well-being.
Link to the study : https://tinyurl.com/mrw86wk4
