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Chapter 6
biofilm former (in comparison to S. Agona SL483 and S. Typhimurium
strains SL1344 and S09-0419) using the CBR, however this was not evident
when using the microtitre plate system for the extended period of time. In
general, the results of the microtitre plate method were broadly
inconsistent.
Secondly, when using the CBR, the mean log density of cells recovered
from the surfaces generally increased when the biofilm development time
was extended from 48 to 168 hours. The microtitre results suggest in most
instances the biofilm density did not increase for most strains after the
extended period of time at 22°C. This result corresponds with what others
have reported in this area [56, 149]. However the mean optical density of
biofilm did increase over the extended period of time when the microtitre
plate was assessed at 37°C. This suggests that given different conditions
such as increased temperature or providing a larger surface area for biofilm
development such as the CBR, biofilm density can increase over the
extended period of time. This may have serious implications for the food
industry if methods for reducing biofilm activity are based around the
microtitre plate at room temperature it may underestimate the ability of
strains to form more dense biofilm over an extended period of time or if
the temperature in the environment increases.
6.6. The resistance of an established biofilm to disinfectant
treatment
Disinfectant companies often market their products as active against
Salmonella however these claims are often based on suspension test
results only [134]. To investigate the efficacy of disinfectants in food
processing and domestic environments, the methods applied should be as
close to real life conditions as possible [130] . In light of this, the CBR was
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