Table 3. Cell length and cell wall thickness of L. monocytogenes strains.

Strain	Average cell length (µm) ± SDa		Average cell wall thickness (nm) ± SDb
	BHI medium	BHI medium + PenG	BHI medium	BHI medium + PenG
EGD	1.52 ± 0.25	1.35 ± 0.22c	26.52 ± 1.82	30.78 ± 2.86c
Δ fri	2.02 ± 0.39d	2.37 ± 0.76c,d	25.59 ± 1.67	18.81 ± 2.49c,d

^aMean cell lengths were determined by measuring 100 cells of each strain grown in the presence (+ PenG) or absence of 0.09 µg/ml penicillin G. The analysis was performed using two independently prepared samples. From each independent sample, equal numbers of cells were analyzed ± standard deviation (SD).

^bMean cell wall thickness was determined by measurement of 20 cells of each strain grown in the presence (+ PenG) or absence of 0.09 µg/ml penicillin G. The analysis was performed using two independently prepared samples. From each independent sample, equal numbers of cells were analyzed ± standard deviation (SD).

^cSignificant differences following growth in the presence and absence of penicillin G (Student's t-test; P<0.05).

^dSignificant differences between the studied strains (Student's t-test; P<0.05).