Production of Bacillus thuringiensis in “On Farm” Biofactories Is So Efficient Like a Commercial Product to Control Spodoptera frugiperda (Lepidoptera: Noctuidae)

The biological control of pests and diseases in Brazilian crops has increased substantially, and the large-scale multiplication of microorganisms, a practice known as “On Farm”, is now being used by farmers. In this study, we aimed to produce and evaluate the quality of Bacillus thuringiensis var. kurstaki strain HD-1 in “On Farm” biofactories under three aeration rates (0.2, 0.5 and 0.8 air volume/volume of medium/min) (vvm), with regard to the production of endospores and crystals, contaminants, and to calculate the lethal concentration 50 (LC50) against Spodoptera frugiperda larvae. After 48 h, the number of viable spores differed significantly between 0.2 (5.75 × 107), 0.5 (1.33 × 108) and 0.8 (5.40 × 108) vvm. The culture media did not show enough selectivity. A significant difference was observed for the LC50 calculated for 0.2 vvm (7.06 × 104), 0.5 vvm (2.07 × 104), 0.8 vvm (4.40 × 103), and the commercial product (3.79 × 103). The results of this study showed that the aeration rate affects the multiplication efficiency of B. thuringiensis in biofactories. In addition, post-process quality control analyses found no pathogenic contamination, reinforcing the safety and viability of the production process. The 0.8 vvm rate resulted in the greater production of spores and crystals, and statistically similar results to the commercial product for the control of S. frugiperda.