Selected ESR: Hugo Matias Duarte
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Supervisor Name: Debora Berti, Emiliano Fratini

Industrial Supervisors: Jeremie Gummel, Eric Robles

Recruiting Organisation: CSGI at University of Florence



Understanding the Mode of Action of Different Chemistry on the Microstructure of Bacteria


Determine the impact of antimicrobial agents on the microstructure of bacteria across a wide range of scale from microns (size of bacteria) to nm (cell wall and cytoplasmic biopolymers)



Due to the progressively increasing resistance of bacteria towards antibiotics, the search for different approaches and alternative therapies to suppress bacterial growth in different cases is a top priority. Bacterial cells need to maintain their membrane architecture for regulating the trans-membrane potential, essential requisites for growth as well as metabolic activity. The cell can be disrupted, for example, by cationic antimicrobial agents and changes in bacterial microstructure at multiple scale can be accessed by small angle scattering techniques.

As a structure sensitive tool, SAXS provides a rapid feedback on drug induced ultrastructural alteration in bacteria which the most studied are E. colicells. At the ESRF we obtained useful SAXS information regarding changes in the morphology of the bacteria when exposed at different pH (2, 7 and 12) and concentrations of hydrogen peroxide. As can be seen in figure 1, it was possible to observe multi-scale changes to the bacterial cell from 1 nm to above 1000 nm. This way, the effect of different actives is being assessed as well by applying mathematical models to quantify the changes in the microorganisms’ morphology. 

In support of the synchrotron SAXS information, dynamic/static light scattering and electrokinetic or zeta potential measurements have been used as bench top techniques. Moreover, we aim at obtaining information regarding reaction kinetics, mode of action and structure-function relationships between the active chemistry and the cellular response.