Biology subjects

Biehl, L.

Publications and source records attributed to Biehl, L..

2 recordsLinked to original sources

bioRxiv2026

Age-specific modulation of gut-brain axis metabolites by galacto-oligosaccharides and nutrient blends in early childhood

ObjectivesGut microbiome-derived metabolites, including short-chain fatty acids (SCFA) and tryptophan derivatives, are key mediators of the gut-brain axis. We examined how early-life nutritional interventions influence these metabolites during critical neurodevelopmental periods. MethodsUsing a standardized ex vivo fermentation system, we assessed the effects of galacto-oligosaccharides (GOS), nutrient blends (vitamins, minerals, amino acids), and their combinations on the gut microbiome of infants (2-4 months, n=6) and young children (2-3 years, n=6). ResultsBaseline microbiome composition differed by age: infants showed low -diversity and high interpersonal variability, while young children exhibited more adult-like profiles. Nutrient blends increased propionate/butyrate ratios and branched-chain fatty acids (BCFA) in young children, alongside B-vitamin and amino acid-derived metabolites, including neuroactive compounds (indole-3-carboxaldehyde, imidazoleacetic acid, pipecolinic acid). Combining nutrient blends with GOS produced synergistic effects on propionate (infants) and 2-hydroxyisocaproic acid (HICA, both groups). GOS-containing treatments strongly promoted Bifidobacteriaceae, driving production of acetate, HICA, N-acetylated amino acids, aromatic lactic acids, and acetylagmatine; in young children, also butyrate and {gamma}-aminobutyric acid (GABA). DiscussionGOS alone and combined with nutrient blends modulated microbiome-derived metabolites linked to the gut-brain axis. Synergistic effects on GABA, acetylagmatine, and HICA suggest roles in neurotransmission, neuroprotection, and immune-brain signaling. Despite shared bifidogenic effects, age-specific differences indicate developmental stage influences intervention outcomes. Further studies should explore neurodevelopmental benefits of these combinations and metabolites.

microbiology↗

bioRxiv2025

Clinical and Genomic Characterization of Recalcitrant Enterococcal Bacteremia: A Multicenter Prospective Cohort Study (VENOUS)

BackgroundPatients with recalcitrant enterococcal bloodstream infections are at greater risk of adverse outcomes. We identified patients in the 2016-2022 Vancomycin-Resistant Enterococcal Bacteremia Outcomes Study (VENOUS) cohort experiencing recalcitrant bloodstream infections for further clinical and genomic characterization. MethodsBacteremia episodes were considered "persistent" if there was a lack of clearance on day four while receiving [≥] 48 hours of active therapy and recurrent if there was clearance during hospitalization with a subsequent positive culture (collectively, "recalcitrant" bacteremia). A matched comparison group of non-recalcitrant bacteremia patients was chosen in a 2:1 control:case ratio. Isolates were subjected to short- and long-read whole-genome sequencing. Hybrid assemblies were created using a custom pipeline. Findings. A total of 46 recalcitrant infections from 41 patients were identified. Patients with persistent bacteremia were more often admitted to the ICU upon admission relative to controls. E. faecalis strains causing persistent infections had a significantly higher proportion of genes associated with carbohydrate utilization relative to controls. Representation of functional groups associated with mutated genes was disparate between E. faecium and E. faecalis index and persistent isolates, suggesting species-specific adaptation. DiscussionEnterococcal isolates causing recalcitrant bacteremia were genomically diverse, indicating that strain-specific signatures are not drivers of persistence. However, comparisons of index vs. persistent isolates revealed that E. faecium may be genetically pre-adapted to cause persistent infection, and site-specific structural variation during infection suggests the role of differential gene expression in adaptation and persistence. This data lays groundwork for future studies to define signatures of enterococcal adaptation during bacteremia.

genomics↗