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Chapter 2
2.6.6. Mean log 10 density of S. Typhimurium biofilm cells
Table 2.4 displays the mean log 10 density values for all S. Typhimurium
strains. As demonstrated in the results, there was only minor differences in
the mean log 10 density of biofilm recovered from the surfaces for the S.
Typhimurium strains, despite incomplete removal of the S. Typhimurium
LT2 (see Figure 2.5 and 2.6).This suggests that the cell counts most likely
underestimated the biofilm density. Nevertheless the LT2 strain formed the
most dense biofilm on 4 of the 5 surfaces compared with other S.
Typhimurium strains. However, due to the incomplete removal from the
surface the LT2 strain the data for this strain were excluded from all
statistical comparisons as the cell counts could not be considered as
reflecting the full biofilm density. When the S. Typhimurium strain LT2 was
excluded from all comparative work a trend towards more dense biofilm
formation by the S. Typhimurium strain S09-0419 across all 5 surfaces was
observed.
Table 2.4 also displays the difference in mean log 10 densities of S.
Typhimurium cells recovered from the surfaces (indicated in table as p
values). The results presented in table 2.4 indicate that there were only
marginal difference between the S. Typhimurium strains examined and in
most is not cases not likely to be significant (p>0.05 for 4 of 5 comparisons
between SL1344 and S09-0419). The largest difference between strains
(difference in mean log 10 density) was between the two strains S08-0408
and S09-0419, the S09-0419 strain formed a more dense biofilm on 4 of the
5 surfaces (p