How AFM has contributed to the understanding of bacterial cell wall peptidoglycan structure

The bacterial cell wall is an essential exoskeleton that plays a major role in conferring cell shape, serving as the primary stress-bearing layer, resisting the several atmospheres turgor pressure created by the imbalance in molecular concentrations between the cell interior and the surrounding medium, while also playing a central role in host-pathogen interactions. Over the last two decades, the versatile tool kit provided by atomic force microscopy has aided our understanding of the bacterial cell wall peptidoglycan, revealing its fine nanoscale architecture, and its role in life, death, and resistance of bacteria to antibiotics - paving the way to new potential antimicrobial targets. Here, we summarise current developments in atomic force microscopy for imaging bacterial cell wall peptidoglycan structure with specific focus on the WHO priority pathogens Methicillin-resistant Staphylococcus aureus and Escherichia coli.