{
  "id": 13384809,
  "title": "Exchange of metabolic pathway intermediates as the origin for metabolite cross-feeding interactions in E. coli auxotrophic co-cultures",
  "url": "https://urgent.news/2026/10/10/exchange-of-metabolic-pathway-intermediates-as-the-origin-for",
  "topic": "science",
  "section": "Science",
  "published": "2026-10-10T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.10.08.757639v1?rss=1"
  },
  "original_language": "en",
  "account": "A significant portion of microbes existing in natural environments require a shared exchange of metabolites for growth to occur. The Black Queen hypothesis and related theories explain how genes can be lost and reliance on shared metabolites can develop. However, the process by which metabolite cross-feeding arises and leads to observable community performance remains unclear. This study aims to propose that the exchange of biosynthetic pathway intermediates offers a mechanism for the emergence of metabolite cross-feeding. The researchers focused on E. coli auxotrophs, specifically a methionine auxotroph (ΔmetA) and a panel of histidine auxotrophs. Their investigation revealed that only the ΔhisD histidine auxotroph demonstrated efficient co-culture growth with the ΔmetA strain, indicating a unique role for the final step of histidine biosynthesis. This step involves converting histidinol to histidine. The co-culture of ΔmetA and ΔhisD strains accumulated significant levels of extracellular histidinol (200 M), suggesting a potential mechanism for metabolite exchange. The spent media from these co-cultures supported the growth of all histidine auxotrophs except ΔhisD, confirming that histidinol, not histidine, was the dominant exchanged metabolite. Further observations showed that ΔmetA effectively converted histidinol to histidine only under conditions of methionine limitation, implying that nutrient limitation facilitated the overflow of converted histidine to the extracellular environment. To evaluate whether histidinol exchange could account for the observed co-culture behavior, the researchers developed a mechanistic model. This model connected extracellular histidinol dynamics to co-culture growth through the independently measured conversion capacity of the ΔmetA strain. Using experimentally derived parameters, the model accurately predicted co-culture growth based on the measured histidinol-to-histidine conversion flux. The model's ability to replicate the timing and magnitude of growth and population dynamics supports the idea that histidinol accumulation enabled the conversion-driven supply of histidine, which sustained ΔhisD, while also linking growth between the two strains. In summary, this study suggests that metabolite cross-feeding in syntrophic co-cultures can emerge from the accumulation of pathway intermediates and their conditional conversion under nutrient limitation, offering a plausible explanation for the rapid establishment of mutualistic interactions.",
  "summary": "A large fraction of microbes in natural environments are auxotrophs that rely on metabolite exchange for growth. The Black Queen hypothesis and related frameworks explain gene loss and reliance on shared metabolites. Yet it is not fully understood how metabolite cross-feeding emerges and gives rise to experimentally observable community performance. Here, we propose that exchange of biosynthetic…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}