Biology Reference
In-Depth Information
3.3.4 Presence of genes associated with E. coli surface structures
Genes were screened by a PCR based method. Results are given in Fig. 3.4 . Of all genes tested,
the presence/absence of the fimbrial/afimbrial adhesin encoding gene Afa was most associated,
but not statistically significant (
p = using Fisher's exact test), with attachment efficiency,
since the gene was absent in three of the ten strains with low attachment efficiency, and present
in all tested strains (10) with high attachment efficiency. The fimH gene of the type I fimbriae
was present in all strains used in the PCR analysis, and so were the genes ompC , slp , and surA .
Their presence was therefore not associated (
0.21
, Fisher's exact test) with high or low
p =
1
attachment efficiencies.
Group A
Group B
Gr oup C
Group D
Α
Strain
UCFL-94
0.32
X
X
X
X
X
X
X
UCFL-131
0.40
X
X
X
X
X
X
UCFL-71
0.40
X
X
X
X
X
1923
0.44
X
X
X
X
X
X
X
X
X
X
2007
0.46
X
X
X
X
X
X
2160
0.46
X
X
X
X
1991
0.47
X
X
X
X
X
X
X
X
2621
0.49
X
X
X
X
X
X
X
X
X
1924
0.50
X
X
X
X
X
X
2216
0.51
X
X
X
X
X
X
2606
1.01
X
X
X
X
X
X
2134
1.09
X
X X
X
X
X
X
2637
1.16
X
X
X
X
X
1625
1.16
X
X
X
X
X
X
X
X
X
X
2059
1.22
X
X
X
X
X
X
X
X
2052
1.22
X
X
X
X
X
1935
1.25
X
X
X
X
X
X
2041
1.42
X
X
X
X
X
X
X
X
X
X
1514
1.61
X
X
X
X
X
X
X
2049
2.10
X
X
X
X
X
X
X
Figure 3.4:
Results of the PCR analyses. A “X” indicates the presence of the gene. The
strains used were grouped in 'low attachment efficiency' (upper ten strains) and
'high attachment efficiency' ('lower ten strains). Group A: autotransporter
proteins, group B: fimbriae and adhesins, group C: pili, group D: other
The genes flu , iha , bfpA were present in, resp., 40%, 40%, and 25% of strains analyzed, and for
all cases, there was no relation between presence/absence of the gene and attachment efficiency (
0.65
p = , resp.). Of course, the presence of a gene does not automatically
indicate that the protein encoded by that gene is also expressed in the outer surface membrane of
the E. coli strains, and therefore the conclusion that these genes were not involved in initial
attachment was not justified. However, apparently, the presence of the genes was apparently not
p =
,
p =
0.65
and
1
 
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