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Mechanical stability of individual bacterial cells under different osmotic pressure conditions: a nanoindentation study of Pseudomonas aeruginosa

Lizeth García-Torres Orcid Logo, Idania De Alba Montero Orcid Logo, Eleazar Samuel Kolosovas-Machuca Orcid Logo, Facundo Ruiz Orcid Logo, Sumati Bhatia Orcid Logo, Jose Luis Cuellar Camacho, Jaime Ruiz-García Orcid Logo

Beilstein Journal of Nanotechnology, Volume: 16, Pages: 1171 - 1183

Swansea University Author: Sumati Bhatia Orcid Logo

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DOI (Published version): 10.3762/bjnano.16.86

Abstract

Nanomechanical maps to test the mechanical response of the outer envelope of Pseudomonas aeruginosa were obtained utilizing atomic force microscopy in force-volume mode in the low range of loading forces when exposed to hypotonic (Milli-Q water), isotonic (PBS), and hypertonic (0.5 M NaCl) solutions...

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Published in: Beilstein Journal of Nanotechnology
ISSN: 2190-4286
Published: Beilstein-Institut 2025
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URI: https://cronfa.swan.ac.uk/Record/cronfa70125
Abstract: Nanomechanical maps to test the mechanical response of the outer envelope of Pseudomonas aeruginosa were obtained utilizing atomic force microscopy in force-volume mode in the low range of loading forces when exposed to hypotonic (Milli-Q water), isotonic (PBS), and hypertonic (0.5 M NaCl) solutions. Imaging and mechanical testing showed that bacteria are highly resilient to deformation and can withstand repetitive indentations in the range of 500 pN. Analysis of force spectra revealed that although there are differences in the mechanical response within the first stages of nanoindentation, similar values in the slopes of the curves reflected a stable stiffness of about k B = 20 mN/m and turgor pressures of P t = 12.1 kPa. Interestingly, a change in the nonlinear regime of the force curves and a gradual increase in maximal deformation by the AFM tip from hypotonic to hypertonic solutions suggest a softening of the outer envelope, which we associate with intense dehydration and membrane separation between inner and outer envelopes. Application of a contact mechanics model to account for the minute differences in mechanical behavior upon deformation provided Young's moduli in the range of 0.7-1.1 kPa. Implications of the presented results with previously reported data in the literature are discussed.
Keywords: AFM; force spectroscopy; membrane rigidity; nanomechanical mapping; osmotic shock
College: Faculty of Science and Engineering
Funders: Deutsche Forschungsgemeinschaft (DFG) – Project ID: 458564133; Royal Society of Chemistry (RSC) RG\R1\241050; National postdoctoral Fellowship program SECIHTI (CONACYT) Mexico
Start Page: 1171
End Page: 1183

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