The tested pH range for strain J12 to grow and express inhibitory activities was between 4.0 and 10.0. The highest biomass (OD600 = 3.83) and maximum inhibitory zone (28.2 mm) were observed at pH 8.0. pH 7.0–10.0 was a suitable range for the strain to express higher bacterial biomass and inhibitory activities, but it failed to grow under acidic conditions (Fig. 3a).