Studies onBacillus thuringiensis H-14 strains isolated in Egypt-III. Selection of media for δ-endotoxin production.

Several medium ingredients locally available in Egypt were investigated for their ability to support δ-endotoxin production by two mosquito-toxic strains ofBacillus thuringiensis H-14 usingCulex pipiens for the bioassay of δ-endotoxin. Soya beans, black-eyed beans, common peas and lentils supported good production of toxin whereas peanuts, fodder yeast, cheese whey and corn steep liquor gave only low amounts of toxin. Molasses as the sole carbon source at 2 and 3% (w/v) with soya (or Proflo) as the sole nitrogen source at 3% gave the best yields of toxin for strain M1 and S128 respectively.