bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.64898/2026.07.21.739833

Environmental history shapes host-associated dynamics of sporulating and non-sporulating bacterial subpopulations during infection

Toukabri, H.·Buisson, C.·Le Vern, Y.·Sausset, A.·Bourge, M.·Slamti, L.
View original source ↗Export metadata ↓

Abstract

Host-associated environments represent ecological contexts that can structure microbial population dynamics, yet their effects on sporulating pathogens remain poorly understood. We investigated how passage through a natural insect host shapes population-level traits in the entomopathogen Bacillus thuringiensis. Using Galleria mellonella larvae, we compared the characteristics of bacterial populations extracted from insect cadavers with those maintained under in vitro conditions. Passage through the host generated a distinct population structure, characterized by the stable coexistence of sporulating and non-sporulating bacteria and a larger non-sporulating fraction than in in vitro cultures. Host-extracted bacteria exhibited a different morphology and higher virulence than in vitro-grown populations, the latter being largely due to the non-sporulating fraction of the population, as shown by reinfection experiments with each subpopulation isolated via fluorescence-activated cell sorting. On the other hand, all subpopulations persisted similarly in the host and completed the infection cycle. Host-extracted subpopulations also showed increased tolerance to oxidative stress, consistent with an adaptation to conditions encountered within insect cadavers. Furthermore, competition assays revealed that non-sporulating bacteria from insect cadavers outcompeted sporulating cells, whereas the opposite was observed for in vitro-grown bacteria. In addition, spores produced in the host displayed reduced heat resistance but germinated more efficiently than laboratory-derived spores, highlighting environment-dependent properties which may affect transmission potential. Together, these results demonstrate that the host-associated ecological context drives functional differentiation within bacterial populations and modulates key traits linked to survival, competition, stress tolerance and persistence, emphasizing the importance of host-associated environments in structuring ecological properties of sporulating pathogens.

Explore related subjects

microbiologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Toukabri, H., Buisson, C., Le Vern, Y., Sausset, A., Bourge, M., Slamti, L.. 2026-07-21. Environmental history shapes host-associated dynamics of sporulating and non-sporulating bacterial subpopulations during infection. https://doi.org/10.64898/2026.07.21.739833

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

A population-scale landscape of the subgingival microbiome reveals divergent routes to periodontal dysbiosis

Periodontitis is an archetypical mucosal inflammatory disease in which microbiome dysbiosis at the tooth-epithelial interface interacts with host genetic and behavioral risk factors to drive immune-mediated tissue destruction. Although subgingival microbiome compositional shifts are thought to parallel disease severity, microbiome variation at the population-level and its relationship to periodontal clinical phenotypes and disease-modifying factors remain poorly defined. Here, we use unsupervised manifold learning to map the compositional landscape of the subgingival microbiome in 1,355 adults spanning periodontal health to severe periodontitis. We identified eight latent microbiome states organized along a branching continuum from eubiosis to dysbiosis. An intermediate microbial configuration marked ecological destabilization and bifurcation into two distinct periodontitis-associated dysbiotic trajectories, distinguished by links to gingival inflammation and smoking. Although the microbiome trajectories broadly tracked periodontal destruction, a minority of individuals showed discordant microbiome-clinical phenotypes, with some individuals with periodontitis retaining otherwise eubiotic microbiomes enriched for low-abundance pathobionts, while some cases of health or mild disease had highly dysbiotic communities, suggesting distinct host susceptibility. Together, these findings define a population-scale ecological landscape of the subgingival microbiome, reveal divergent trajectories to periodontal dysbiosis, and highlight heterogeneity in the relationship between microbial community structure and clinical disease expression.

microbiology↗
bioRxiv2026

Beta-lactam enhancement against methicillin-resistant Staphylococcus aureus by cell wall blockade is autolysis-dependent: a butyrolactone derivative as case in point

Methicillin-resistant Staphylococcus aureus (MRSA) is non-susceptible to beta-lactams. Blockade of cell wall biosynthesis is a potential target for beta-lactam enhancement but requires further investigation. A butyrolactone derivative enhanced beta-lactams against MRSA strains by reducing the availability of D-Ala-D-Ala. Unlike D-cycloserine, it did not inhibit D-Ala-D-Ala ligase (Ddl). Nor did it show an additive or synergistic effect when combined with cycloserine, indicating a unique mechanism for blocking cell wall precursor production that does not involve the traditional Lipid II pathway. Notably, beta-lactam potentiation by our chemical or D-cycloserine was highly dependent on the intrinsic autolytic ability of the tested MRSA strains. Strains that resisted lysis upon Triton X-100 exposure showed a minimal increase in beta-lactam susceptibility, whereas highly autolytic strains showed significant changes in their beta-lactam MICs. We have thus identified autolytic ability as the Achilles Heel in the strategy of targeting cell wall biosynthesis for beta-lactam potentiation.

microbiology↗
bioRxiv2026

Rapid and largely reversible shifts in the canine fecal metabolome during dietary change

Diet can rapidly change the fecal metabolome, but less is known about recovery after the original diet is restored. We used untargeted UPLC-MS metabolomics to analyze 72 fecal samples from nine Pumi dogs during an owner-managed switch from dry food to raw food and back to dry food. Diet phase accounted for a large proportion of variation in both ionization modes. More than 13,000 LC-MS features changed at the first sampling point after the switch to raw food, with a similarly large response after return to dry food. Among features significant in both comparisons, more than 99% changed in opposite directions. At the final sampling point, no positive-mode (ESI+) features and only 13 negative-mode (ESI-) features differed from the second dry-food baseline under the same threshold. BARF-associated patterns persisted in analyses excluding individual dogs and in pedigree-adjusted candidate models, although individual feature effects depended on normalization. Putative metabolites from several biochemical classes differed in their response and recovery. The fecal metabolome therefore changed rapidly and returned largely toward baseline, with differences among dogs.

microbiology↗