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Chapter 2
indicated that there may also be other components responsible for
variation and that attachment may be strain dependent. Previous authors
have suggested the surfaces properties can influence the amount of
bacterial attachment and subsequent biofilm formation [103].
Joseph et al. found that biofilm development was dependent on
substratum with two Salmonella strains (S. Weltevreden and un-typable
Salmonella denoted as “FCM40”) [71]. Salmonella formed the most dense
biofilm on plastic followed by cement and stainless steel respectively.
Joseph et al. also found that inactivation of S. Weltevreden biofilm cells
with hypochlorite (no cells detected) was more rapidly achieved on cement
and steel than plastic (15 min vs. 20 minutes). Similar results were
displayed for the FCM40 strain, with a slightly higher exposure time
necessary (20/25minutes) [71]. However it is difficult to define the extent
to which one can generalise from the two strains studied.
Previous research has demonstrated that the level of bacterial attachment
to stainless steel can be subject to the surface roughness and finish of the
steel [103, 164]. Korber et al. demonstrate that surface roughness can
influence S. Enteritidis susceptibility to disinfectants [102]. The presence of
crevices in a glass flow cell appeared to protect the S. Enteritidis from
treatment with the disinfectant trisodium phosphate (TSP). The
researchers found almost 100% of biofilm cells were killed from the model
containing a smooth substratum, whereas up to 83% of cells on a rough
surface remained viable after contact with the same concentration of TSP.
The research also indicated the size of the crevices influenced the biofilm
with smaller crevices supporting bacterial survival and the thickness of the
biofilm after contact with the disinfectant [102].
Stocki et al. also highlight that the extent of surface area (related to layers
of plastic material) may also influence S. Enteritidis biofilm development on
surfaces. Results indicated that the type of smooth materials such as vinyl
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