Protatrans – growth biostimulants for centomopathogenic bacteria Bacillus thuringiensis

The study investigates the use of protatran compounds as growth stimulators for Bacillus thuringiensis bacteria, which are widely used as producers of biopesticides. Cultivation of the Bacillus thuringiensis strain subsp. kurstaki was carried out in a Luria-Bertani (LB) liquid medium. Protatrans (2-Me-C6H4OCH2COO- were added to the NN+(CH2CH2OH)3 (1), 4-Cl-C6H4 -SCH2COO-NN(CHCHOH) (2) and 4-Cl-CSOCHCOO NN+(CH2CH2OH)3 (3) media in concentrations of 1×10-4–1×10-8wt %. The LB medium without the addition of compounds 1–3 was used as a control. Cultures were incubated at a temperature of 30°C for 24 hours. The number of Bacillus thuringiensis cells was determined by serial dilution. The maximum growth was observed in a medium containing 1×10-4wt % of protatran 3. The number of cells was almost 10 times (966.7%) higher than in the control. In media with 1×10-5, 1×10-6, 1×10-7 and 1×10-8 wt % of compound 3, the number of cells was 4–7 times higher than in the control (by 371.7–666.7%). Protatrans 1 and 2 had a positive effect on Bacillus thuringiensis, increasing the number of cells by 83–292% compared to control. Therefore, it was demonstrated for the first time that commercially available non-toxic protatran compounds in microconcentrations are powerful growth stimulators for the entomopathogenic bacteria Bacillus thuringiensis. This indicates the potential for significant improvement and cost reduction of biotechnology for the production of bacterial insecticides based on Bacillus thuringiensis, used in agriculture, forestry and homesteads to control harmful insects.