Novobiocin

We assessed the hemolytic activities of LAB strains showing antagonistic activity during initial screening by the presence of α/α (a small zone of greenish-brownish discoloration of the medium, indicating reduction of hemoglobin to methemoglobin), β/β (clear, colorless or light yellow zone surrounding the colonies depicting total lysis of red blood cells), and γ/γ (with no change observed in the medium) hemolysis following the protocol of Maragkoudakis et al. (2006) (link). In the antibiotic susceptibility test, we examined promising screened and characterized LAB isolates using the agar disc diffusion method (Bauer et al., 1966) (link). Twelve antibiotics were tested (Hi-Media): penicillin G (2 units), ceftriaxone (30 µg), ampicillin (25 µg), vancomycin (30 µg), oxacillin (1 µg), streptomycin (10 µg), chloramphenicol (30 µg), gentamicin (10 µg), erythromycin (10 µg), tetracycline (10 µg), novobiocin (30 µg), and ciprofloxacin (10 µg). Isolates were categorized as sensitive (≥21 mm), intermediate (16-20 mm), or resistant (≤15 mm) (Liasi et al., 2009) . The multiple antibiotics resistance (MAR) index was determined for each probiotic strain as previously described by Ngwai et al. (2011) .