Bacterial adhesion and biofilms on surfaces

Bacterial adhesion has become a significant problem in industry and in the domicile, and much research has been done for deeper understanding of the processes involved. A generic biological model of bacterial adhesion and population growth called the bacterial biofilm growth cycle, has been described and modified many times. The biofilm growth cycle encompasses bacterial adhesion at all levels, starting with the initial physical attraction of bacteria to a substrate, and ending with the eventual liberation of cell clusters from the biofilm matrix. When describing bacterial adhesion one is simply describing one or more stages of biofilm development, neglecting the fact that the population may not reach maturity. This article provides an overview of bacterial adhesion, cites examples of how bac-terial adhesion affects industry and summarises methods and instrumentation used to improve our understanding of the adhesive prop-erties of bacteria

Use of the atomic force microscope to determine the effect of substratum surface topography on bacterial adhesion

Changes in surface roughness and topography on the macroscopic scale are known to affect bacterial attachment and retention. Little quantitative information is available as to how changes in surface topography on the micron and submicron scale affect the strength of bacterial attachment to substrata. A novel method is described using the atomic force microscope where a varying shear/lateral force (in nanonewtons) is used to detach individual bacterial cells from various substrata of different surface topographies. Lateral changes of 0.1 μm in the surface topography are sufficient to affect the strength of bacterial attachment. An increase in applied force from 4 to 8 nN was necessary to move bacteria retained in surface defects of approximately 1 μm wide and 0.2 μm deep compared with cells attached on smooth surfaces