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Poster

Measuring species interactions during biofilm development.

Abstract : Biofilms are structured communities of microorganisms and are now recognized as the prevailing mode of life of bacteria in natural and man-made environments. Bacterial biofims participate therefore to a large number of beneficial ecological processes but can also have a considerable negative impact on human well-being throughout their involvement in biodeterioration or biofouling processes and even by causing serious infectious diseases. The functional roles of biofilms leading to these positive or negative impacts are intimately related to the spatial architecture and organization of the community. Since biofilms are recognized as complex associations of numerous different species in our environments, a better deciphering of the nature of the interactions between bacterial populations become an important ecological parameter required to better understand, predict and control biofilm functions. Individuals of two different bacterial species can interact in biofilms in different ways. They may compete for ressources and space, just as conspecific individuals do. They may also interact in more complex ways, in which intra-specific interactions differ from inter-specific ones. For instance, different species may share different common goods or have complementary feeding needs. We are here interested in these last types of interactions, which modify the dynamics of each species in the presence of the other. These interactions make the coupled dynamics of the two species different from the juxtaposition of the two monospecific dynamics, so that it should be possible to detect these by the careful analysis of biofilm growth patterns. In this aim, mono-species and bi-species biofilms were grown under flow in three-channel flow-cells. 3D biofilm structure was then scanned every hour during biofilm development using time-lapse confocal laser scanning microscopy combined to genetically modified bacterial strains expressing constitutively green or red fluorescent protein (GFP or mCherry). We built a simple individual-based model of biofilm development, where intra-specific interactions did not differ from inter-specific ones. We developed a statistical method to parameterize the different processes represented in the biofilm model (growth, mobility, attachment and detachment) using our temporal series of biofilm images obtained by confocal microscopy. By setting the model directly with these experimental data, we limit the number of hypothesis that we formulated and therefore, we limit the bias caused by these hypothesis in the model. This parameterization relied on the comparison between the structural patterns observed during biofilm development in vitro and in silico. Namely, biofilm structural patterns were quantified thanks to a number of summary statistics (number of clusters and the first four moments of the cluster size distribution) at the different time points both in the simulations and in the experimental images. And model parameter values with which model simulations best fit empirical observations were retained. We demonstrate in this contribution that our simple model of biofilm growth can be parameterized with temporal series of biofilm images, and that it satisfactorily represents the biofilm growth dynamics observed in our experiments. We finally demonstrate how to use this simple model of biofilm growth as a null model to detect non-trivial interactions between pairs of bacterial species.
Keywords : GFP MCHERRY
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Poster
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https://hal.inrae.fr/hal-02598488
Déposant : Migration Irstea Publications <>
Soumis le : vendredi 15 mai 2020 - 23:50:33
Dernière modification le : lundi 18 mai 2020 - 14:37:13

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  • HAL Id : hal-02598488, version 1
  • IRSTEA : PUB00038250

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Citation

Arnaud Bridier, T. Bouchez, Franck Jabot. Measuring species interactions during biofilm development.. ISME 14 Symposium, Aug 2012, Copenhague, Denmark. pp.1, 2012. ⟨hal-02598488⟩

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