The impact of recombinant fusion-hydrophobin coated surfaces on E. coli and natural mixed culture biofilm formation

Abstract

The impact of increased surface hydrophobicity on biofilms regarding retardation, repulsion, or attraction was studied with hydrophobin modified glass substrata. Recombinantly produced fungal hydrophobins forming self-assembled monolayers were used as the surface coating. The adsorption dynamics of hydrophobins were analysed with a quartz crystal microbalance which showed the surface coating to be rapid and stable. The change of surface wettability was determined by water contact angle measurements and demonstrated an increase in hydrophobicity in range of 60–62°. The homogeneity of the monolayers was demonstrated by immunofluorescence microscopy. Atomic force microscopy was applied to visualise the uniform texture of the coated materials. The hydrophobin coatings had no impact on different biofilms in terms of spatial distribution, cell numbers, and population composition. In consequence, hydrophobicity might not represent an important parameter for biofilm formation. Nevertheless, recombinant hydrophobins are suitable for large scale surface modification and functionalization with bioactive molecules.

Keywords:

• recombinant fungal hydrophobins
• surface modification
• wettability
• biofilm formation

Acknowledgements

This work was funded by a grant from the German Federal Ministry of Education and Research to T.S. as part of the research program ‘Geotechnologien’ (03G0723). The authors thank the BASF-SE (C. Bollschweiler and M. Karos) for providing the recombinant fusion-hydrophobins H*Protein A and H*Protein B.