Atomic Force Microscopy Study of Living Baker's Yeast Cells

Currently, Atomic Force Microscopy (AFM) has a wide range of applications in a variety of disciplines of science and industry including biology and medicine. Despite the maturity of the AFM technique, it is still finding new opportunities in visualization of biological materials and biomolecular processes. The most frequent and ordinary application of AFM is surface topology and morphological studies. This paper describes educational application of AFM in observation of a living cell wall structure. For the following study we have selected Sacchoromyces cerevisiae cells, better known as baker's yeast cells that are available in any supermarket and widely used for fermentation control of food and drinks, and as a leavening agent in baking. The sample preparation and measurements are described. Living yeast cells were prepared in solutions containing glucose or sodium chloride. Proposed AFM based protocol allows the researcher to keep baker's yeast cells alive, and to observe them in air conditions. The experiment is suitable for Master and/or Ph.D. students and is designed to show the main principles of the Bio-AFM operation. In some particular cases, this protocol may be adoptable for bachelor students, who have already completed an extended course in nanotechnology, biotechnology or microbiology. To show educational suitability, the protocol has been tested in the environment of educational laboratory and performed by students studying physics, chemistry, biotechnology and biology.