Nitrogen source
(1.0 %w/v)
Antibacterial activity
(inhibition zone in mm)
  Bacillus pumilus Aeromonas formicans 
Beef extract   9.6 ± 0.76 10.6 ± 0.50
Malt extract (control) 16.5 ± 0.87 20.2 ± 0.29
Tryptone   9.3 ± 0.58 10.7 ± 0.58
Peptone   9.0 ± 1.00 10.5 ± 0.50
Ammonium nitrate   8.2 ± 0.50   9.6 ± 0.50
Potassium nitrate   8.3 ± 0.58   9.7 ± 0.58
Calcium nitrate   8.0 ± 1.00   9.5 ± 0.50
Table 5: Selection of suitable nitrogen source for antibiotic production by cupplate method.