Unveiling how bacteria modify the surface of solid walls in their close environment at the nanoscale is an important step in nanotechnology and bioengineering as well as in geomicrobiology and fundamental surface chemistry/physics. A multidisciplinary team from the University of Paris-Saclay (Laboratoire de Physique des Solides and Institute for Integrative Biology and Cell) has, for the first time, quantitatively linked the stages of corrosion on a metal nanofilm with the actions of bacteria. This work opens new perspectives on the stability and reactivity studies of the first liquid-solid contact nanolayers.
Bacteria have evolved on earth for billions of years and have managed to colonize all ecological niches. Their metabolic diversity is so vast that they play a major role in the biogeochemical cycles of our planet. Understanding the mechanisms by which bacteria interact with the first interfacial layers of the solid matter that surrounds them is an important issue and researchers opted here to work with thin iron films, with a surface area of centimeters and a thickness of nanometers. The nanofilm’s opacity being related to its thickness, it is then possible to measure both the nanofilm’s degradation and to localize and quantify the bacteria dynamics in situ and in real time by simple optical means (Figure 1).
Figure 1. Microscopic observations of Shewanella Oneidensis MR1 bacteria in contact or close to the surface of an iron nanofilm (left) and a glass slide (right).
This experimental work published in the journal ACS Central Science indicates a homogeneous corrosion of iron nanofilms triggered suddenly by bacteria (Figure 2). Experiments reveal in particular rapid motions of Shewanella oneidensis MR1 bacteria during iron dissolution. Mutants of S. oneidensis as well as other bacterial species such as E. coli and L. plantarum are also able to induce corrosion. All the experiments highlight more generally the role of electroactive respiratory proteins and soluble secreted molecules in the modification of the surface properties of nanofilms. This scientific result can also be found on the website of the CNRS Institute of Physics.
Figure 2. Temporal variation of the nanofilm’s thickness (A) when bacteria are added at time t = 0 (red symbols). Corrosion suddenly appears at t = tonset creating a sudden electron flow as revealed by the electrical intensity measurements (B) performed on another sample.
Reference
Biocorrosion on Nanofilms Induces Rapid Bacterial Motions via Iron Dissolution
M. Lherbette, C. Regeard, C. Marlière, E. Raspaud
ACS Central Science, 2021, 7, 1949-1956
doi: 10.1021/acscentsci.1c01126
Scientific news from the CNRS Institute of Physics
Contacts
LPS: Eric Raspaud
I2BC: Christophe Regeard
