Effect of wetting phenomena in biofilm formation and removal

Contact person: F. Recupido [federec91@gmail.com]

 

The project belongs to Marie Curie Initial Training “Complex Wetting Phenomena” and it is in collaboration with University of Naples, “Federico II”, in Italy.

Biofilms are structured multicellular communities of bacteria, that colonize biotic and abiotic surfaces. The implications of biofilms are several, since they are known to drive many biotechnological processes such as bioremediation, waste water and solid waste treatments. However, they represent a huge contamination source especially in industrial settings, since they are responsible of biofouling, product spoilage, corrosion and reduction of production efficiency. Therefore, the necessity to remove biofilms from industrial facilities represents a big challenge. In Figure 1, examples of biofilm contaminations.

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Figure 1: Left: Image of biocorrosion in industrial water systems [1], Right: S. aureus biofilm on a catheter [2]

The aim of this project is to study the effect of the wetting phenomena in biofilm formation and removal.

For the aim, an innovative device, recently developed for the evaluation of wetting/dewetting behaviour of complex substrates, driven by external forces, will be used  (for the description, see Wetting and Dewetting of complex substrates driven by external forces, Figure 2).

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Figure 2: An innovative device for the study of wetting/dewetting of complex substrates [3]

Using the device above, wetting/dewetting phenomena of bacterial droplets for bacterial migration and contamination purposes on different substrates, will be evaluated [4], (Figure 3). Moreover, the interactions between droplets of cleaning solutions and mature biofilms, for removal purposes, will be also analysed.

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Figure 3: Top view of colony surfing. A 2µl drop is still immobile at t = 1hour after its deposition (left). Sliding of the bacterial droplet after 8 h on Agar medium (right). [4]

Parameters that will be evaluated, are:

  • Dynamic contact angles
  • Dynamic surface tensions
  • Biofilm thickness and composition.

Methods:

  • Optical microscopy;
  • Scanning electronic microscopy;
  • Confocal microscopy;
  • QCM-D;
  • Profilometry

References

  1. http://biofilmbook.hypertextbookshop.com
  2. http://www.infectioncontroltoday.com
  3. Evgenidis, et al., Kerberos:A three camera headed centrifugal/tilting device for studying wetting/dewetting under the influence of controlled body forces, Colloids Surf. A: Physicochem. Eng. Aspects (2016).
  4. Hennes et al., Active depinning of bacterial droplets: the collective surfing of Bacillus subtilis, PNAS, 2017.