Effect of mineral nutrition sources on the growth and toxin formation of the entomopathogenic bacteria Bacillus thuringiensis

Mineral composition of culture medium has been studied for its effect on the processes of growth, spore-and-toxin formation of entomopathogenic bacteria Bacillus thuringiensis. It has been shown that salts Na2SO4, Na2SiO3.9H2O, MgSO4.7H2O increase the yield of biomass and endotoxin; FeSO4.7H2O, CaCl2, MnSO4.4H2O increase only the yield of biomass; CdSO4.7H2O and CoCl2.6H2O--inhibit the processes of spore-and-toxin formation, but increase the cell titre. A complex of mineral salts has been found which takes positive effect on the biomass accumulation, delta-endotoxin synthesis and insecticide activity of the studied bacteria. It is shown that the drug "Gumat" besides other elements of the culture medium completely provides bacteria with necessary mineral compounds.