Different bacteria respond to their environments through alteration of cell morphology and through formation of communities of bacteria across surfaces, known as called biofilms. These lifestyle changes are survival strategies that occur in response to a range of environmental stresses that include the physical (e.g. osmotic stress), chemical (e.g. antibiotics) and biological (e.g. host immune system). Although it has been recognized for many years that bacteria can transition between different lifestyles, the molecular mechanisms that orchestrate these various processes are largely unknown.
The complex surface of a bacterium is the first line of defence against these environmental stresses. In Gram positive bacteria, the bacterial surface consists of a plasma membrane covered with a thick layer of peptidoglycan. In Gram negative bacteria, a thin layer of peptidoglycan separates the inner and outer membranes. In many bacteria, the cell wall is encased in a thick layer of entangled polysaccharide, called the capsule. Recently we developed nanomechanics methodologies to interrogate the behaviour of bacteria to provide the first in situ quantitative measurements of the biophysical behaviour of the capsule and cell wall in physiologically relevant conditions. We also determined the mechanism of interaction of antimicrobial peptides with live bacteria using time-resolved microspectroscopies. This talk gives an overview of these results, which give new insight into the mechanobiology of bacterial survival and adaptation.