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Table 1 Expression of promoter- hly fusions in response to the addition of penicillin G as determined by a hemolytic activity assay

From: Identification of a ferritin-like protein of Listeria monocytogenesas a mediator of β-lactam tolerance and innate resistance to cephalosporins

Hemolytic activitya

Strain

15b

18b

37c

41b

195d

198c

199c

201c

203d

K

10.2 ± 2.6

8.7 ± 1.6

13.2 ± 3.8

20.7 ± 2.5

30.8 ± 1.2

20.3 ± 1.4

12.2 ± 0.6

21.5 ± 1.3

19.6 ± 1.1

PenG

20.4 ± 1.9**

13.3 ± 0.3*

32.5 ± 4.5**

36.1 ± 1.9**

54.8 ± 1.8 **

29.5 ± 1.7*

33.9 ± 1.6**

28.5 ± 1.7**

55.5 ± 3.4**

  1. a The hemolytic activity was measured for selected strains carrying promoter-hly fusions grown for 2 h in the presence (PenG) or absence (K) of penicillin G (0.03 μg/ml), using b0.5%, c1% or d2% suspensions of SRBC. The results are the average of three independent experiments, each performed in triplicate ± the standard deviation. Asterisks indicate significant differences according to Student’s t test (*, P < 0.05; **, P < 0.01).