Mathematical relationships between spore concentrations, delta-endotoxin levels, and entomotoxicity of Bacillus thuringiensis preparations produced in different fermentation media

► Bacillus thuringiensis (Bt) biopesticide production was conducted in different media. ► Spore and delta-endotoxin concentrations and entomotoxicity (Tx) were determined. ► Relation between delta-endotoxin and spore concentrations followed the Power law. ► The specific Tx with respect to spores followed the Power law. ► Tx and delta-endotoxin concentration is linear relation on semi log scale.