Microbial Conlonization in Confined Chaotic Mixtures

Informations projet

MicroMix

N° de convention de subvention: 898575

DOI

10.3030/898575

Projet clôturé

Date de signature de la CE 2 Mars 2020

Date de début 1 Mai 2020

Date de fin 6 Août 2022

Financé au titre de

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Coût total

€ 196 707,84

Contribution de l’UE

€ 196 707,84

Coordonné par

UNIVERSITE DE RENNES I
France

Periodic Reporting for period 1 - MicroMix (Microbial Conlonization in Confined Chaotic Mixtures)

Période du rapport: 2020-05-01 au 2022-04-30

Résumé du contexte et des objectifs généraux du projet

The project tackles the issue of biofilm development in the porous microstructure of the soils, where it is submitted to the porous media flows and the subsequent mixing.

Bacteria strive in these hidden and complex environments. Most times, their can be observed attached to the surface, upon which they have formed biofilms. Since soils are generally opaque, it is impossible to monitor in the environments the formation of such biofilms. The project aims at reproducing the mixing conditions of the soil, and observe biofilm development in it.

First, we needed to build the tool, which we successfully achieved thanks to microfluidics devices which mimics the soil's mixing properties.

Second, we observed the growth of biofilm in various mixing conditions (i) without antibiotics and in homogeneous conditions and (ii) in the presence of a mixture of antibiotics, for which the mixing properties define the viable space available for the growth of the biofilm.

Results:

1) We managed to recreate the transport properties of a 3D soil in a quasi-2D microfluidic device, by unveiling the strong ties between the dispersion and the chaotic mixing properties.

2) We observed that the biofilm would grow wider in the geometries which would disperse AND mix solute better.

3) In the presence of antibiotics, we saw that the biofilm would grow better in the less mixing geometries, where the viable space would be larger.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

The ER had to invent a new device, coined Chaotic Networks, to mimic soil transport.

In fluoresence microscopy, he performed several experiments:

- conservative dispersion experiment, where a passive tracer was injected amid water. (Abiotic)
- reactive transport experiments, where reagents would produce a fluorescent tracer. (Abiotic)
- biofilm growth experiment under continuous perfusion of growth media. (Biological)
- biofilm growth experiment under continuous perfusion of a mixture of antibiotics. (Biological)

All experiments allowed the analysis of transport properties from the pore scale to the sample scale, thanks to image analysis.

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

The microfluidic chip invented during MicroMix enables the many actors revolving around this thematic (academic labs, but also soil engineers and hydrologist) to observe microbial life in realistic mixing conditions.

Because it is a frugal technology, and can be adapted to a regular microscope, it can easily be brought to the classroom.

Because of its simplicity, it will be declared as an invention before further communication.

The scientific findings of MicroMix enables us to better our understanding of physics and life of the underground, by unveiling the spectacular impact of the microstructure of the geometry over the large scale, altogether on the dispersion of a chemical, the mixing of reactive compounds and the growth of biofilm.

The chip could be used for inlab test of bioremediation and/or decontamination of soils, identifying how antibiotic resistance can build up in a bacterial community in the soils.

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