A bidirectional nanAKE locus enables sialic acid catabolism in gut microbiome member Hungatella hathewayi

Summary

This study identifies Hungatella hathewayi, an overlooked member of the human gut microbiome enriched in long-lived individuals, as a capable sialic acid degrader. Using functional complementation and comparative genomics, the authors characterise a bidirectional nanAKE locus that enables robust growth on sialic acids as a sole carbon source, despite phylogenetic distance from canonical E. coli systems. The findings expand understanding of sialic acid utilisation across diverse gut bacteria and suggest H. hathewayi may contribute to modulating gut sialic acid levels and associated inflammation.

Regional applicability

Although conducted with fecal samples from healthy human donors (likely North American), the findings describe fundamental microbial metabolism conserved across human populations. The results are globally applicable to understanding human gut microbiome function and may inform dietary or probiotic interventions targeting sialic acid metabolism in United Kingdom populations, though direct validation in UK-specific cohorts would strengthen applicability claims.

Key measures

Growth assays on sialic acid-supplemented media; heterologous complementation in E. coli knockout strains; sequence conservation analysis of NanA catalytic residues; phylogenetic comparison of transporter and regulatory proteins

Outcomes reported

The study identified and functionally characterised a bidirectional nanAKE locus in Hungatella hathewayi that enables growth on sialic acids as a sole carbon source, validated through growth assays and heterologous complementation in E. coli knockouts. The research demonstrates that H. hathewayi possesses conserved catalytic residues despite phylogenetic distance from E. coli, with novel transporter and regulatory proteins related to other gut anaerobes.

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