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Chapter 5
strains. However the method used by Bridier et al. differs substantially
from other methods described in this chapter. In order, to attach a dye
(Syto9 – green fluorescent nucleic acid marker), the bacterial attachment
was interrupted after 1 hour when the wells were rinsed with 150mM of
sodium chloride to eliminate any non-adherent cells. This was followed by
adding sterile TSB and 5µl Syto9 to wells of the microtitre plate after which
the plates were incubated for 24 hours at 30°C to allow biofilm
development. This method is similar to that described by Peeters et al. who
used a 4 hour initial incubation period before rinsing the wells of a
microtitre plate when using a crystal violet and Syto 9 to quantify biofilm
formation of clinically associated organisms [229].
As previously described in chapter 3, Vestby et al. used the microtitre plate
method and a pellicle formation assay to investigate the biofilm forming
capability of 21 S. enterica strains including S. Agona, S. Montevideo, S.
Senftenberg and S. Typhimurium [56]. They concluded that particular
strains which persisted in the environment were able to form a more dense
biofilm than the other strains examined. Moreover, the results indicated
that using this method, S. Agona and S. Montevideo strains formed a more
dense biofilm than S. Typhimurium and S. Senftenberg [56].
5.1.4. Assessing the efficacy of disinfectants using the microtitre plate
method
Although there is a substantial body of literature investigating Salmonella
biofilm formation using the microtitre plate method in most instances the
research is switched to detachable surfaces once large scale screening is
complete and the research moves into disinfectant assays [56, 113, 134,
159, 227, 230]. Disinfectant assays are frequently performed on detachable
surfaces suitable for traditional methods of plate count enumeration as
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