ABSTRACT
The biofilm structure is held together and attached to the interface by the extracellular polymeric substances (EPS) produced by the biofilm organisms (Christensen, 1989; Geesey, 1982; Neu and Marshall, 1990; Neu, 1992; Neu, 1994; Sutherland, 1983; Sutherland, 1995). EPS may be polysaccharides, pro teins, nucleic acids or (other) amphiphilic polymers (Neu, 1996). All o f these polymers have a high affinity for water. Therefore, the aqueous medium in which the biofilm structure is embedded represents a key factor for transport processes to, from and within the biofilm structure. Thus, biofilms are highly hydrated structures that may have a water content of up to 98% (Christensen and Characklis, 1990). The high water content eventually will determine the proper technique to microscopically examine the natural three-dimensional (3D) hydrated biofilm architecture.
