Pz was measured as the ratio of the diameter of the colony to the total diameter of the colony plus the hyaline zone. Readings using a digital caliper were taken directly on the Petri dishes, after placing the plates on predefined background.
Digital images were obtained using a digital camera placed at 30 cm from plates.
The Adobe Photoshop Measurement Tool was used to perform readings of digital images,
after setting the measurement scale (cm). Four blind examiners (two with an advanced level of experience in microbiology and two beginners) performed all readings twice, with a 24-h interval between them.