To evaluate the interactions between the antagonist and the
pathogen in culture, 6-mm diameter plugs were cut from 7-day-old
PDA cultures of A. flavus and then placed on another PDA plate (15 ml/
plate) seeded with 1.0 ml of different treatments of B. megaterium.
The treatments were as follows: (A) autoclaved culture; (B) culture
filtrate; (C) 1×108 CFU/ml unwashed cell culture mixture; and (D)
1×108 CFU/ml washed cell suspension and sterile distilled water as a
control. Autoclaved cultures were prepared by autoclaving a sample
containing B. megaterium in culture broth for 20 min at 121 °C.
Culture filtrates were prepared by filtering the supernatant of
centrifuged culture of the antagonist through a 0.2-μm polycarbonate
membrane filter (Wang et al., 2008). Unwashed cells from 24-h
cultures were adjusted to 1×108 CFU/ml by adding additional culture
filtrate. Plates were incubated for 7 days at 37 °C. Fungal growth was
recorded after 7 days. Growth inhibition was calculated as the
percentage of inhibition of radial growth relative to the control
(Bouchra et al., 2003). Three replicates were used per treatment and
the experiments were repeated twice.