Gut Bacteria Enzyme Found to Break Down Heat-Processed Food Compounds, Producing Novel Biogenic Amines
Researchers have discovered that an enzyme in common gut bacteria can degrade N-epsilon-carboxymethyllysine (CML), a compound formed during thermal food processing, producing previously unknown biogenic amines. The enzyme, ornithine decarboxylase SpeC from enterobacteria, acts on CML and related modified lysine derivatives through a low-level 'underground' catalytic activity. This finding suggests a previously unrecognized communication axis between thermally processed dietary compounds and gut microbial physiology, with potential implications for host health.
A new study published on bioRxiv reports that the enterobacterial enzyme SpeC — an ornithine decarboxylase — can metabolize N-epsilon-carboxymethyllysine (CML), a prevalent advanced glycation end product generated during thermal food processing such as cooking. Operating at a low catalytic rate of approximately four molecules per enzyme per minute, SpeC converts CML into carboxymethylcadaverine and also acts on other modified lysine derivatives, including formylated, monomethylated, and dimethylated lysine, generating novel biogenic amines not previously described. Beyond simple degradation, this activity allows Escherichia coli to use CML as a sole nitrogen source, and in certain strains it reinforces pH-stress responses that support bacterial survival under the mildly acidic conditions typical of the colon. Genomic analyses show that SpeC orthologs are widespread across human gut microbiomes, with their prevalence correlating with geographic region, dietary patterns, and disease states. The authors propose that this metabolic pathway represents a diet-microbiome communication axis linking the consumption of thermally processed foods to microbial physiology and potentially to host health outcomes.
What's missing
As a preprint, this study has not yet undergone formal peer review, and its findings should be interpreted with caution. The study does not establish direct causal links between SpeC-mediated CML metabolism and specific host health outcomes; the 'hypothesized host impacts' remain speculative. The physiological concentrations of CML and related compounds reaching the colon in vivo, and whether the observed underground catalytic rate is sufficient to be biologically meaningful at those concentrations, are not fully addressed. The functional significance of the newly identified biogenic amines (e.g., mono- and dimethylcadaverine, formylcadaverine) for host physiology is unknown.
What different sources said
- bioRxivCenter
Deciphering underground decarboxylase activity towards Nε-modified lysine derivatives in enterobacteria.
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