Discrimination between random and non-random processes in early bacterial colonization on biomaterial surfaces: application of point pattern analysis

Abstract

The dynamics of adhesion and growth of bacterial cells on biomaterial surfaces play an important role in the formation of biofilms. The surface properties of biomaterials have a major impact on cell adhesion processes, eg the random/non-cooperative adhesion of bacteria. In the present study, the spatial arrangement of Escherichia coli on different biomaterials is investigated in a time series during the first hours after exposure. The micrographs are analyzed via an image processing routine and the resulting point patterns are evaluated using second order statistics. Two main adhesion mechanisms can be identified: random adhesion and non-random processes. Comparison with an appropriate null-model quantifies the transition between the two processes with statistical significance. The fastest transition to non-random processes was found to occur after adhesion on PTFE for 2–3 h. Additionally, determination of cell and cluster parameters via image processing gives insight into surface influenced differences in bacterial micro-colony formation.

Keywords:

• bacterial colonization
• point-pattern analysis
• bacterial adhesion
• biofilm
• biomaterials
• image processing

Acknowledgements

This work was supported by the Jena School for Microbial Communication (JSMC/MikroInter) funded by the DFG and the State of Thuringia. Fruitful discussions with J. Schleicher and M. Föge are gratefully acknowledged.