Data from 37 healthy children (aged 7-12) showed that, while there were some similarities in the gut microbiota with adults, there was significantly greater abundance of Bifidobacterium spp., Faecalibacterium spp., and members of the Lachnospiraceae.
In addition, there were significant differences for the relative abundances of genes involved in the synthesis of some vitamins, the degradation of amino acids, oxidative phosphorylation, and inflammation.
“As with other developmental processes, childhood appears to represent a unique transitional stage with respect to the gut microbiome,” wrote the researchers in Microbiome.
“Although the healthy pediatric gut microbiome harbors several adult-like features, it also retains many of its own distinct compositional and functional qualities. Such characteristics could contribute to age-adjusted definitions of the healthy gut microbiome, serve as diagnostic biomarkers to delineate life stage and direct appropriate medical treatment, and be important to consider in the development of microbiome-directed therapies, particularly those targeted toward microbiome restoration.”
Led by Emily Hollister, PhD, from Baylor College of Medicine, the researchers used 16S rRNA gene and shotgun metagenomic sequencing to analyze the gut microbiota of healthy pre-adolescent children.
“It is thought that childhood may provide opportunities for microbiome interventions to promote health or prevent disease,” they explained. “As such, it is vital to establish a baseline understanding of pediatric GI microbiome structure and function, the degree to which these vary among healthy children, and the extent to which specific microbial features are unique to childhood, as opposed to infancy, when digestive function is immature, or adulthood, when presumed to be mature.”
The data indicated that, at the phylum level, the pediatric gut microbiome is dominated by Bacteroidetes (about 40% of the microbiome) and Firmicutes, with wide variations in the ratio between these types.
At the genus level, Bacteroides, Faecalibacterium, Alistipes, Ruminococcus, and Roseburia were the main genera.
Dr Hollister and her co-workers also report that the gut microbes in healthy children are enriched for genes for the synthesis of folate (vitamin B9). This enrichment with genes for folate synthesis has previously been reported in infants, with folate associated with the support and synthesis of DNA.
Other studies have also reported that the gut microbiota of adults can produce vitamin B12 more that infants. “In contrast, we found that many genes involved in cobalamin biosynthesis were significantly enriched in children,” they wrote.
“We also observed that the gut communities of children were enriched with respect to the metabolism of the amino acids tyrosine, lysine, cysteine, and methionine,” they added. “These amino acids serve as substrates for the production of biogenic amines and neurotransmitters, both of which function as critical links along the gut-brain axis.”
“Our results support and extend a growing body of evidence suggesting that GI microbial communities undergo succession in concert with the maturation and development of their human hosts,” they wrote. “Perhaps more importantly, our results also indicate that, although the pediatric gut microbiome is characterized by levels of taxonomic and functional richness that rival those found in healthy adults, both taxonomic and functional differences distinguish the gut microbial communities of healthy children and adults from one another.”
3:36. doi: 10.1186/s40168-015-0101-x
“Structure and function of the healthy pre-adolescent pediatric gut microbiome”
Authors: E.B. Hollister EB, et al.