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Communication Dans Un Congrès Année : 2013

Emergence of a synergistic diversity as a response to intra-specific competition in Pseudomonas putida mixed biofilm

Emergence d'une diversité synergique en reponse à une compétition intra-spécifique dans des biofilms mixtes

Arnaud A. Bridier
T. Bouchez

Résumé

In natural and man-made environments, biofilms are known to be complex associations of microorganisms which development is controlled by a network of bacterial interactions. As biofilm is a dynamic environment, these interactions evolve over time, often illustrating the adaptation of the whole bacterial community to its environmental conditions on one hand and of the bacterial community members to each other on the other hand. From this process the structure and the functional properties of the whole biofilm finally emerges. Genetic diversification and selection of variants with increased fitness in the conditions experienced is one of the known mechanisms enabling the adaptation of species to the biofilm way of life. Therefore, a better understanding of the emergence of this genetic diversity and overall the dynamic mechanisms of adaptation of bacterial species in biofilm is thus a first step towards the managing of ecosystem functions and evolution. In this aim, we focused in this work on the adaptation of the model strain Pseudomonas putida KT2440 (GFP-tagged) in mixed biofilm with another strain from the same species (P. putida mCherry-tagged) more recently isolated from roots of plants. We first analysed the emergence of colony morphology variants of Pseudomonas putida KT2440 GFP in pure culture or in mixed biofilms with the P. putida mCherry strain. Three colonies variants of P. putida KT2440 GFP (2000 colonies screened) were obtained from the mixed biofilm of both P. putida strains after 168h of growth whereas no variant was identified from the axenic P. putida KT2440 biofilm on the basis of colony morphology. The three variants were then phenotypically characterized (growth rate, cell surface properties, swimming, swarming, macrocolonies) and their ability to form biofilms alone or with the P. putida mCherry strain was analysed using 3D confocal microscopy. Variants exhibited distinct phenotypes and produced biofilm with specific architecture in comparison with the ancestor. In the mixed biofilms, KT2440 variants also better competed with the P. putida mCherry strain compared to the ancestor. The mix of the three variants and ancestor produced biofilm with high biovolume and has a better ability to compete the P. putida PCL1480 mCherry strain illustrating the synergistical effect of strain association in biofilm production and thus in the adaptation and survival of the whole P. putida KT2440 GFP population. To sum up, this work provides evidence that an intra-specific competition can foster the emergence of phenotypic diversification which might increase the global fitness of the resulting population and highlights the importance of bacterial interactions in the evolution and adaptation of microbial communities.

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Dates et versions

hal-02598815 , version 1 (16-05-2020)

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Arnaud A. Bridier, T. Bouchez. Emergence of a synergistic diversity as a response to intra-specific competition in Pseudomonas putida mixed biofilm. BioMicroWorld2013 V international conference on environmental, industrial and applied microbiology, Oct 2013, Madrid, Spain. pp.1. ⟨hal-02598815⟩

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