Colonization and Succession within the Human Gut Microbiome by Archaea, Bacteria, and Microeukaryotes during the First Year of LifeOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This longitudinal study tracked how the infant gut is colonized during the first year of life, resolved to all three domains of life. It examined bacteria, archaea, and microeukaryotes such as fungi. Methods combined quantitative real-time PCR with 16S and 18S rRNA gene amplicon sequencing. Fecal samples were collected around days 1, 3, 5, 28, 150, and 365. The team compared vaginal versus cesarean delivery.
Who was studied?
The cohort was 15 healthy infants born in Luxembourg between 2012 and 2014. Eight were delivered vaginally and seven by cesarean section. A total of 65 fecal samples were collected across six time points. Mean gestational age was about 38.7 weeks and mean birth weight about 3273 grams. Mothers were aged 24 to 42. Most infants received breast milk, some formula or a combination.
What were the most important findings?
Sequences from all three domains were detectable in every meconium sample. Archaea were detected by PCR in 91 percent of samples and fungi in 37 percent, both earliest in vaginally delivered infants. The methanogen Methanobrevibacter appeared at day 1 in one infant. Cesarean-delivered infants showed delayed colonization and lower bacterial load at days 3 and 150. Bacteroidetes were significantly depleted from day 5, raising the Firmicutes to Bacteroidetes ratio at days 5, 28, and 150. Bacteroides colonization was delayed in cesarean infants, while skin and oral taxa were enriched. Microeukaryotic communities fluctuated strongly and never stabilized.
What are the greatest implications of this study?
The results extend the known cesarean-linked colonization delay from bacteria to archaea and microeukaryotes. This broader disruption may alter early immune programming, since the neonatal microbiome shapes immune maturation. Breast milk feeding appeared to speed early fungal diversification. The cohort was small, so causal links to later disease risk such as obesity or allergy remain unproven and need larger follow-up studies.