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Figure 13.2.
AFM was used to stretch molecules on
P. putida
KT2442, and these
data were it with either the freely jointed chain (FJC) or extensible freely jointed
chain (FJC+) models. Experimental conditions and model equations are described
elsewhere (Refs. 25 and 56).
used the FJC+ model to measure
Kuhn lengths and segment elasticities on two types of LGG bacteria.
29
The
modelling was helpful in allowing the authors to conclude that the wild-type
LGG bacteria have two types of surface polysaccharides, one group rich in
mannose that is characterized by moderate extensions, and a group rich in
galactose, the latter which can have much longer extensions. These results
were used to discuss how LGG bacteria may bind to intestinal tissue and
interact with immune receptors in the host.
Bacterial proteins and proteoglycans can usually be more appropriately
itted with the WLC model. For example, the WLC model could describe the
mechanical properties of mucilage material isolated from marine diatoms,
30
surface proteins of
In this same study, Francius
et al.
Staphylococcus aureus
31
and the unfolding of an
Escherichia
coli
transmembrane protein.
32
However, none of the models may work for
very rigid biomolecules, such as pili, as was observed by Touhami
et al.
when
studying
expressing type IV pili.
11
As none of the
available polymer models could it the extension proiles from the AFM data,
the authors speculated that this was due to the very stiff nature of pili, in
comparison with other bacterial macromolecules.
Pseudomonas aeruginosa
13.3 BACTERIAL INTERACTIONS WITH BIOMATERIALS
On implantation, a medical device is immediately coated with physiological
molecules (luids, peptides, etc.), forming a conditioning ilm.
Regardless
of the material's surface chemistry at implantation, a gradual build-up of
33,34
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