Survival of E. coli and L. monocytogenes in biofilms after PUV-light treatment. PUV-light treatment was performed under different exposure conditions, i.e., different times (in s) and distances (in cm) from the UV source to the samples. A Lettuce leaves incubated at 30°C for 24 h; B lettuce leaves incubated at 30°C for 48 h; C LDPE films incubated at 30°C for 24 h; D LDPE films incubated at 30°C for 48 h. Values are presented as the mean ± SE of two experiments performed in triplicate. Columns mean, bars SE. Columns labeled with different letters indicate significant differences (P < 0.05).