AFM imaging of isolated microbes is a key application in microbiology research and education. Microbes are the new workhorses of biomanufacturing. Yeast, bacterial, and viral cultures are commonly grown in suspension or on agar plates, and AFM can be a powerful tool to analyze uniformity and the composition of these cultures. Suspensions can be deposited on a suitable substrate (glass, polymer, or mica), washed and dried for imaging. Colonies can be picked off an agar plate and immediately imaged in the AFM.

The most simple and accessible sample are bacterial colonies grown on agar plates. Colonies can be captured and compared by blotting a substate on the desired area and placing the substrate directly in the AFM. Without any sample preparation, images like these can be captured within a few minutes.

Bacterial colony picked off an agar plate and imaged by AFM within minutes of colony picking (50×50 um scan). The height, width and length of individual cells is easily measured.

The same colony in 3D visually confirms the uniformity of the bacterial cells.

For microbial samples of more complex environments check the application notes on AFM of Biofilms and AFM of Microbiomes.

Both the MolBio3D and the HR-AFM are suitable for this task. The MolBio3D benchtop system excels at rapid imaging of dry samples, whereas the HR-AFM accepts broader sample geometries and allows for scanning in liquids at the expense of floor space in the lab.