JPK reports on the use of AFM and single-cell force spectroscopy at the Interdisciplinary Nanoscience Center.
Dr Rikke Meyer at the Interdisciplinary Nanoscience Center in Denmark is currently looking into biofilm formation from bacteria using atomic force microscopy (AFM) and single-cell force spectroscopy.
AFM and optical microscopy are used to visualise bacterial cells and to study the interaction forces between cells and an abiotic substrate.
The motivation for using AFM in Meyer’s research was firstly to obtain detailed images of bacterial cells without extensive sample preparation.
Furthermore, as she is interested in the interactions between bacteria and abiotic surfaces, she and her team use AFM force spectroscopy to quantify these interaction forces.
AFM is one of several techniques used in these studies. These also include brightfield microscopy, fluorescence microscopy, confocal laser scanning microscopy, scanning electron microscopy and transmission electron microscopy.
Meyer said: “As a microbiologist, I work with very heterogenous samples and it is not feasible to use AFM imaging to locate the field of interest, as large areas of the sample are often visualised to locate a site of interest.
“In the combined system, we can use the optical image to locate cells of interest before engaging the AFM for imaging or other measurements.”
She added: “AFM has mostly been used to study bacterial cells that are isolated in pure culture. However, the vast majority of the bacterial species we know to date have not been isolated and can only be studied in situ.
“Fluorescence labeling allows a rough identification of bacteria directly in the sample and fluorescence imaging can thus be used to locate cells of interest before AFM imaging begins. The combination of AFM with optical imaging is thus particularly important for the analysis of bacteria in environmental samples.”
