With its ability to observe single microbial cells at nanometre resolution, to monitor structural dynamics in response to environmental changes or drugs, and to detect and manipulate single-cell surface constituents, atomic force microscopy (AFM) provides new insight into the structure–function relationships of cell envelopes. This emerging field of microbial nanoscopy should have an important impact on many disciplines of microbiology, including cellular and molecular microbiology, pathogenesis, diagnosis, antimicrobial therapy and environmental microbiology.
How cell envelope constituents are organised and how they interact with the environment are key questions in microbiology. Unlike other bioimaging tools, AFM provides information about the nanoscale surface architecture of living cells and about the localization and interactions of their individual constituents. These past years have witnessed remarkable advances in our use of the AFM molecular toolbox to observe and force probe microbial cells. Recent milestones include the real-time imaging of the nanoscale organization of cell walls, the quantification of subcellular chemical heterogeneities, the mapping and functional analysis of individual cell wall constituents and the analysis of the mechanical properties of single receptors and sensors.