Highly active local strains of B. sphaericus were used along with the reference strains 1593 and 2297 to optimize the biocide production. The optimum conditions were as follow: 20% of total flask volume, pH 7.0, inoculum size 3-5×10 4 cfu / ml, 30° C and 200 rpm/5 days. Glycerol was the best C source at 0.5%; a great suppression up to >80% with propionic acid. All tested strains failed to synthesize biocide in the presence of inorganic N as a sole source; beef extract gave the supreme yield. Mg 2+ was necessary for maximal productivity; however, Ca 2+ damaged the fermentation. The uppermost productivity was achieved from 25 g/l fodder yeast, 500 ml/l corn steep liquor and 0.3 g/l MgSO 4 as a medium. Chicken feather at 30 g/l proved to be an excellent mono component; a superlative improvement was achieved when feather (3.0%) supplemented with 0.03% of MgSO 4 .