Humidity-Dependent Bacterial Cells Functional Morphometry Investigations Using Atomic Force Microscope

Hike Nikiyan,Alexey Vasilchenko,Dmitry Deryabin

doi:10.1155/2010/704170

Hike Nikiyan, Alexey Vasilchenko + Show 1 more

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https://doi.org/10.1155/2010/704170

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Abstract

The effect of a relative humidity (RH) in a range of 93–65% on morphological and elastic properties of Bacillus cereus and Escherichia coli cells was evaluated using atomic force microscopy. It is shown that gradual dehumidification of bacteria environment has no significant effect on cell dimensional features and considerably decreases them only at 65% RH. The increasing of the bacteria cell wall roughness and elasticity occurs at the same time. Observed changes indicate that morphological properties of B. cereus are rather stable in wide range of relative humidity, whereas E. coli are more sensitive to drying, significantly increasing roughness and stiffness parameters at RH ≤ 84% RH. It is discussed the dependence of the response features on differences in cell wall structure of gram-positive and gram-negative bacterial cells.

Highlights

Significant progress in using of atomic force microscope (AFM) as a tool for investigations of eukaryotic and prokaryotic cells has been reached during past decade [1, 2]
Though the method of atomic force microscopy is relatively new, it could become widespread in microbiological studies that use bacteria as sensors, changing their morphological characteristics at various exposures
The surface roughness analysis and determination of bacterial cell elasticity were performed for each grade of dehumidification

Summary

Introduction

Significant progress in using of atomic force microscope (AFM) as a tool for investigations of eukaryotic and prokaryotic cells has been reached during past decade [1, 2]. In contrast to traditional methods of visualization— scanning electron and optical microscopy—atomic force microscopy offers important benefits: high spatial resolution, real quantitative data acquisition in three dimensions, relatively simple and nondestructive sample preparation procedure, and flexibility in ambient operating conditions (i.e., without the need for a vacuum or gold sputtering) [3]. AFM makes it possible to probe local surface forces and mechanical properties of biomaterials [4]. Though the method of atomic force microscopy is relatively new, it could become widespread in microbiological studies that use bacteria as sensors, changing their morphological characteristics at various exposures. AFM has been used to study temperature-dependent morphological alterations of prokaryotic cells [7] and effects of antibiotics on E. coli and S. aureus [8]

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