Influence of media composition on the production of d-endotoxin by Bacillus thuringiensis var. thuringiensis.

Powders of edible leguminous seeds, greengram (Vigna radiata) or soybean (Glycine max), were
used as the major protein source with different combinations of soluble starch and/or cane sugar
molasses as the major carbohydrate source for the production of 8-endotoxin by Bacillus thuringiensis
var. thuringiensis serotype 1 in submerged fermentation. The primary product (lyophilized
with 6 g of lactose) yield was 8.7 to 9.1 g/liter from media with dehusked greengram powder and 9.7
to 10.3 g/Iiter from media with defatted soybean powder in basal medium. The toxicity of primary
products was assayed against f&h-in&r Bombyx mori larvae by force-feeding. The primary product
from the medium containing defatted soybean powder and soluble starch gave a maximum
viable spore count of 91.3 x lO?mg, with a corresponding potency of 35,800 IU/mg, whereas the
medium containing dehusked greengram powder and cane sugar molasses gave a spore count of
49.5 x lO%ng, with a highest potency of 38,300 IU/mg. Either legume protein in combination with
cane sugar molasses yielded primary product 2.1 to 2.4 times more potent than the U.S. standard.
The combined carbohydrate source consisting of soluble starch and cane sugar molasses, irrespective
of the source of protein in the media, drastically reduced bendotoxin production, thereby
reducing the potency of the primary products compared to the U.S. standard.