Biomedical Implications of the Porosity of Microbial Biofilms - Porous Media: Applications in Biological Systems and Biotechnology - page 125

bioluminescence method is the noninvasive detection of fluorescent bacteria
using multiphoton laser scanning microscopy. As bacterial expression of fluo-
rescent protein, for example, green fluorescent protein (GFP) and its variants,
does not require any substrate for endogenous production, it is the method of
choice for prokaryotic labeling. Unfortunately, use of GFP is restricted to only
those bacterial species that can produce the fluorescent protein, which elimi-
nates the tracking of some key pathogens, such as Staphylococcus epidermidis
or obligate anaerobes.

4.2 The Life Cycle of Biofilms
Microbial cells embedded within a biofilm (“sessile cells”) differ from their
freely suspended counterparts (“planktonic cells”) by structural organization
assigned as “biofilm architecture.” Characklis (Characklis 1990a) identified up
to eight different processes describing microbial attachment to surfaces result-
ing in biofilm growth and development. These can be reduced to three main
stages: attachment, growth, and detachment from biofilm surface (Figure 4.2).

4.2.1 Microbial Attachment
The solid-liquid interface between a semisolid surface and an aqueous medium,
for example, blood vessel, provides an ideal environment for the attachment
and growth of microorganisms. Understanding the attachment mechanism

Phase variable adhesin expression

Community expansion
- quorum sensing
- motility and chemotaxis
- metabolic interactions
- exopolysaccharide synthesis

Autoaggregation
Microcolony formation

Attachment Adhered

community

FIGURE 4.2
Model describing the specific stages in the development of microbial biofilms.
(From Schembri, M.A., Givskov, M., and Klemm, P., Science's STKE , 2002.
Reprinted with permisison from AAAS.)