Characterization of the salivary microbiome in healthy individuals under fatigue statusOriginal 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?
Researchers compared the salivary microbiome of 7 healthy adults with acute physiological fatigue (induced by prolonged study, confirmed by electroencephalography) against 63 energetic healthy controls. The goal was to see whether fatigue leaves a detectable signature in oral bacteria.
How was it studied?
Saliva DNA underwent 16S rRNA V3 to V4 sequencing, with LEfSe used to find differential taxa and a Boruta-SHAP algorithm used to build a fatigue-classifying model. BugBase predicted community phenotypes and PICRUSt2 predicted functional pathways.
What did they find?
The fatigue group had lower alpha diversity (Simpson index, p = 0.01071) and a distinct community structure (p < 0.05). Streptococcus and Filifactor, both potential periodontal pathogens, were enriched, while health-associated Rothia and Neisseria were depleted. A 15-genus model distinguished fatigue from non-fatigue with an AUC of 0.948, and the fatigue group showed more mobile genetic elements (p = 0.048) but less aerobic (p = 0.006) and biofilm-forming (p = 0.002) bacteria, alongside enriched neuroactive ligand-receptor pathways versus enriched energy metabolism pathways in controls.
Why it matters
The findings point to a possible oral-microbiome-brain axis linking salivary bacteria to fatigue physiology. Saliva could offer a non-invasive biomarker source for assessing fatigue status, though the fatigue group was small at 7 people.