Impact of sodium nitroprusside concentration added to batch cultures of Escherichia coli biofilms on the c-di-GMP levels, morphologies and adhesion of biofilm-dispersed cells

Abstract

Biofilm dispersion can be triggered by the application of dispersing agents such as nitric oxide (NO)-donors, resulting in the release of biofilm-dispersed cells into the environment. In this work, biofilm-dispersed cells were obtained by adding different concentrations of NO-donor sodium nitroprusside (0.5, 5, 50 µM, and 2.5 mM of SNP) to batch cultures of pre-formed Escherichia coli biofilms. Except for those dispersed by 5 µM of SNP, biofilm-dispersed cells were found to be wider and longer than the planktonic cells and to have higher c-di-GMP levels and greater adhesion forces to silicon nitride surfaces in water as measured by atomic force microscope. Consequently, the optimum concentration of SNP to disperse E. coli biofilms was found to be 5 µM of SNP, whose addition to batch cultures resulted in a significant biofilm dispersion and the dispersed cells having c-di-GMP levels, morphologies and adhesion strengths similar to their planktonic counterparts.

Graphical Abstract

Keywords:

• Biofilm-dispersed cells
• Escherichia coli
• sodium nitroprusside (SNP)
• c-di-GMP
• adhesion force
• atomic force microscope (AFM)

Acknowledgements

We would like to thank Prof. Dr. Thomas K. Wood, Biotechnology Endowed Chair and Professor of Chemical Engineering at the Pennsylvania State University, for providing us with the E. coli ATCC 25404; and Dr. Colin Grant, former HITACHI SPM Product Manager (Europe), for helping us solve the technical problems we faced when operating the AFM in a liquid environment.

Disclosure statement

The authors report there are no competing interests to declare.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was financially supported by The Scientific and Technological Research Council of Turkey (TUBITAK) under TUBITAK 3501-Career Development Grant (Project No: 118M404).