Antimicrobial activity assay of free e-PL was measured by
Oxford cup and was used as the control. The sterile Oxford cups
including the supernatant of 100 ll of e-PL solutions (0, 2.0, 4.0
and 6.0 mg/ml) were placed on the surface of the agar. Then the plates were incubated in the agar according to their requirements
for 24 or 48 h. After the incubation, the zone inhibition of the halos
displayed the inhibitory activity.