Atomic force microscopy and optical microscopy: suitable tools for the study of the initial stages of biofilm formation

P. L. SCHILARDI; C. DIAZ; C. Y. FLORES; F. ALVAREZ; M. A. FERNÁNDEZ LORENZO DE MELE

Current Research, Technology and Education Topics in Applied Microbiology and Microbial Biotechnology (Microbiology Book Series)

Formatex

Año: 2010;

Biofilms are communities of microorganisms consisting in a biologically active aggregate of cells immersed in extra-cellular polymeric substances (EPS) and attached on a live or dead surface. Atomic force microscopy (AFM) and optical microscopy (OM), including epifluorescence microscopy (EM) have been proved to be suitable tools in order to follow the initial stages of biofilm development. AFM is a local imaging technique based on repulsive forces between the sample and a tip probe, allowing imaging and quantification of surface topographic features as well as biological elements at the nanometer scale. Changes in cell morphology, orientation, size, flagellar direction, bacterial organization and distribution, and EPS production can be detected by AFM, without sample pretreatment, frequently needed in other microscopic techniques. In this chapter we describe the use of AFM to study the formation of Pseudomonas biofilms (considered models in case of motile bacteria) on substrates with different morphology, roughness and chemical composition. The submicroscale images were complemented with the whole landscape of the biofilm obtained by using OM including EM.