MATHEMATICAL MODELLING OF OPTIMIZATION NUTRIENT MEDIUM COMPOSITION FOR ENTOMOPATHOGENIC BACTERIA STRAIN Bacillus thuringiensis 87/3 CULTIVATION

The aim of the research was to develop an optimal liquid medium composition for bacteria strain B. thuringiensis 87/3 which is the most favorable for the identification the potential production of biologically active components. In this work we have used new entomopathogenic bacteria strain B. thuringiensis var. thuringiensis (Bt H1) № 87/3 selected in vitro, isolated from the larvae of leaf-eating insects natural populations of Leptinotarsa decemlineata Say (L4). Nutrient medium for cultivation of Bt 87/3 was optimized on base a full-fledged xperiment, according to the Box-Behnken (33) plan. Optimumal concentrations were investigated in the medium of carbon source (15 g/l of glucose), nitrogen (10 g/l of corn extract) and phosphorus-containing inorganic salts (1.5 g/l of diammonium phosphate). When this strain grown in periodic conditions at 30 ºC, the number of viable cells reached 4.4.109 cells/ml. Nutrient medium that was optimized can be recommended for cultivation of Bacillus thuringiensis 87/3 in production conditions.