Understanding biofilm adhesion and cohesion forces


Systematically investigate and measure cell-cell cohesion and adhesion versus (i) the effect of biofilm stage & (ii) the surface properties


Selected ESR: Artemis Tsiaprazi-Stamou

Supervisor Name: Serafim Bakalis, Kostas Gkatzionis

Industrial Supervisors: Anju Brooker, Eric Robles, Kevin Wright

Recruiting Organisation: University of BirminghamUK


Microorganisms can live and proliferate as individual cells or they can adhere to any surfaces, where they grow as highly organized multicellular communities, known as biofilms. “Biofilm adhesion” is a term describing the phenomenon of initial bacteria attachment to surfaces, caused by the contribution of attractive and repulsive forces between the two interphases. “Biofilm cohesion” is a term describing the biofilm continuity that leads to biofilm proliferation, caused by the development of forces along the biofilm structure.  In the macro world, biofilm on surfaces is causing problems in many aspects of human life and makes biofilm cleaning an issue of great importance. Thus, in order to find new ways to improve biofilm elimination, we need first to understand the mechanisms involved in biofilm adhesion in the atomic scale. For this reason, colloidal atomic force microscopy will be used for the measurement of biofilm adhesion forces with different materials surfaces. Moving to the mesoscale a micromanipulation technique, built and developed for this project, willbeusedforthemeasurementofcohesionforcesalong the biofilm structure. Finally yet importantly, for evaluating the effectiveness of biofilm cleaning from surfaces, a parallel-plate flow chamber has been designed to measure the biofilm residual contamination after cleaning. 

The bacteria strains currently studied for this project are Pseudomonas Fluorescens NCIMB 9046 and Pseudomonas Putida that grow on various coupon surfaces that are common in industry and in household (stainless steel, polycarbonate, polyethylene etc) using a CDC bioreactor. Confocal Laser Scanning Microscopy in combination with Fluorescence Microscopy are used for biofilm characterization before and after cleaning. 

The most important outcome of this project, is to understand the mechanisms of initial bacterial attachment on various surfaces, as well as the mechanisms that are dominant during their removal, and the ways in which the different substrata and their surface properties affect the phenomenon, in order to create the technologies for the effective prevention and removal of biofilm.