Elastic Properties of Aspergillus nidulans Studied with Atomic Force Microscopy (original) (raw)
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We examined the physical properties of the surrounding yeast cell walls by using atomic force microscopy (AFM). The yeast cells were prepared on a cleaned glass substrate for CM observation and were mechanically trapped into a porous membrane for AFM measurement. The confocal image of the yeast cells was measured in air meanwhile the AFM topography images of the cells were measured in both de-ionized (DI) water (pH = 6.9) and phosphate-buffered saline (PBS) solution (pH = 7.4). No significant differences between the AFM topography images of the yeast cells measured in DI water and in phosphate buffered saline (PBS) solution could be inferred. In order to get the quantitative information on the sample elasticity, the force curves between an AFM tip and the yeast cell have been measured. These curves were measured in both DI water and in PBS solution on the same yeast cell using the same AFM cantilever to get the reliable result. The contact region of these force curves in approach mode was then converted into force versus indentation curves. These curves would be fitted with Hertz-Sneddon model for the calculation of the elasticity. Analysis of the curves indicates that there is a difference of the Young's modulus values of the yeast cell in various environments. These data show that the salt buffer solution increases the rigidity of the biological system.
Application of atomic force microscopy in food microorganisms
Background: Microorganisms play an important role in the food industry. Knowledge of the surface structural and physical properties of food microorganism cells is crucial to gain a detailed understanding of their functions in the natural environment and to explore them efficiently in various food processes. Atomic force microscopy (AFM), as a non-invasive examination tool, has been widely used to image the surface ultrastructure and to probe the physical properties of food microorganisms. Scope and approach: In the current review, detailed applications of AFM in various food microorganisms are outlined, including surface imaging, biomolecular interactions, surface stiffness, and physicochemical properties , which have contributed to our knowledge of cell surface functions. The study emphasises the combination of AFM imaging with force determination, which added a new feature to the AFM technique; i.e., mapping of specific interactions. The combined use of AFM with other complementary techniques for a comprehensive description of cell surface is also reported. Conclusions: and key findings: AFM has given promising results and thus could be a powerful technique for surface characterisation at nanoscale resolution and could provide new insight into the structure-function relationship of microbial surfaces.