Biomedical Engineering Reference
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Fig. 6.9 Effect of copper resistance mechanisms on the survival
E. coli
on copper alloy surfaces
and stainless steel.
E. coli
wild-type strain W3110 (
squares
), its copper-sensitive derivative
ΔcopA
Δcus ΔcueO
(
triangles
) or W3110 harboring the high-level copper resistance system Pco (
circles
)
were applied on dry copper alloy surfaces (
filled symbols
) or stainless steel (
open symbols
). After
the indicated time periods at ambient conditions (23
C(a, c, and d) or 5.5
C(b)), after the
indicated times, cells were removed and CFU counted. Surviving cells were counted as CFU. The
alloys were pure copper (99.9 % Cu) (a and b), “nickel-silver” (maximum of 62 % Cu) (c), Muntz
metal (maximum of 62 % Cu) (d), and stainless steel (AISI 304) (a). All experiments were
measured in triplicates and standard deviations are indicated as error bars [
25
]
Fig. 6.10 Effect of copper preadaptation by
E. coli
strains on copper alloy surfaces. Copper
detoxifying systems were induced by growing
E. coli
cultures in the presence of nontoxic
concentrations of CuCl
2
. Washed cells of
E. coli
wild-type strain W3110 (
squares
) or its
copper-sensitive
ΔcopA Δcus ΔcueO
(
triangles
),
Δcus ΔcueO
(
filled diamond
),
ΔcopA
(
plus
),
ΔcueO
(X),
Δcus
(
open diamond
), or W3110 harboring the high-level copper resistance system
Pco (
circle
) were streaked on 99.9 % copper (a) or “nickel silver” alloy (maximum of 62 % Cu)
(b) surfaces. Average and standard deviations (
bars
) were calculated from tree independent CFU
counts [
25
]
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