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Nutrient conditions are primary drivers of bacterial capsule maintenance in Klebsiella


Rendueles, Olaya; Buffet, Amandine; Rocha, Eduardo P.C. (2021), Nutrient conditions are primary drivers of bacterial capsule maintenance in Klebsiella, Dryad, Dataset,


The fitness cost associated with the production of bacterial capsules is considered to be offset by the protection provided by these extracellular structures against biotic aggressions or abiotic stress. Yet, it is unknown if the capsule contributes to fitness in the absence of these. Here, we explored conditions favouring the maintenance of the capsule inKlebsiella pneumoniae, where the capsule is known to be a major virulence factor. Using short term experimental evolution on different Klebsiellastrains, we showed that small environmental variations have a strong impact on the maintenance of the capsule. Capsule inactivation is frequent in nutrient-rich, but scarce in nutrient-poor media. Competitions between wild type and capsule mutants in nine different strains confirmed that the capsule is costly in nutrient-rich media. Surprisingly, they also showed that the presence of a capsule provides a clear fitness advantage in nutrient-poor conditions by increasing both growth rates and population yields. The comparative analyses of the wild-type and capsule mutants reveal complex interactions between the environment, genetic background and serotype even in relation to traits known to be relevant during pathogenesis. In conclusion, our data suggests there are novel roles for bacterial capsules yet to be discovered and further supports the notion that the capsule role in virulence may be a by-product of its contribution to bacterial adaptation outside the host.


Agence Nationale de la Recherche, Award: ANR 18 CE12 0001 01

Agence Nationale de la Recherche, Award: ANR-10-LABX-62-IBEID

Agence Nationale de la Recherche, Award: PIA/ANR-16-CONV-0005

Fondation pour la Recherche Médicale, Award: EQU201903007835