pH Antibacterial activity
(inhibition zone in mm)
  Bacillus pumilus Aeromonas formicans 
5.0 18.2 ± 0.32 21.2 ± 0.29
6.0 20.5 ± 0.50 22.5 ± 0.50
7.0 18.5 ± 0.29 21.5 ± 0.50
8.0 16.6 ± 0.78 15.6 ± 0.50
Table 7: Determination of optimum initial pH for antibiotic production by cup-plate method.