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The role of extracellular DNA in microbial attachment to oxidized silicon surfaces in the presence of Ca2+ and Na+

Lookup NU author(s): Dr Ana Morales Garcia, Professor Mark GeogheganORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Attachment assays of a Pseudomonas isolate to fused silica slides showed that treatment with DNaseI significantly inhibited cellular adsorption, which was restored upon DNA treatment. These assays confirmed the important role of extracellular DNA (eDNA) adsorption to a surface. To investigate the eDNA adsorption mechanism, single-molecule force spectroscopy (SMFS) was used to measure the adsorption of eDNA to silicon surfaces in the presence of different concentrations of sodium and calcium ions. SMFS reveals that the work of adhesion required to remove calcium-bound eDNA from the silicon oxide surface is substantially greater than that for sodium. Molecular dynamics simulations were also performed, and here, it was shown that the energy gain in eDNA adsorption to a silicon oxide surface in the presence of calcium ions is small and much less than that in the presence of sodium. The simulations show that the length scales involved in eDNA adsorption are less in the presence of sodium ions than those in the presence of calcium. In the presence of calcium, eDNA is pushed above the surface cations, whereas in the presence of sodium ions, short-range interactions with the surface dominate. Moreover, SMFS data show that increasing [Ca²⁺] from 1 to 10 mM increases the adsorption of the cations to the silicon oxide surface and consequently enhances the Stern layer, which in turn increases the length scale associated with eDNA adsorption.

Publication metadata

Author(s): Morales-García AL, Walton R, Blakeman JT, Banwart SA, Harding JH, Geoghegan M, Freeman CL, Rolfe SA

Publication type: Article

Publication status: Published

Journal: Langmuir

Year: 2021

Volume: 37

Issue: 32

Pages: 9838-9850

Print publication date: 17/08/2021

Online publication date: 04/08/2021

Acceptance date: 24/07/2021

Date deposited: 17/08/2021

ISSN (print): 0743-7463

ISSN (electronic): 1520-5827

Publisher: American Chemical Society


DOI: 10.1021/acs.langmuir.1c01410


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