Promising entomopathogenic strain of Bacillus thuringiensis 0428 effective against the Colorado beetle

Most of the world produced biopesticides are made by entomopathogenic bacteria B. thuringiensis. So, searching for new strains of it is always necessary. In 2006, the strain B. thuringiensis 0428 was isolated from the caterpillar of the ringed silkworm. The strain 0428 is entomopathogenic against Colorado beetle larvae. The effectiveness of the strain for 5 days was 100%. On beef-extract agar this Gram-positive bacterium formed round or irregular colonies with an average diameter of 6-10 mm. The relief of the colonies is flat; the surface is matte. Colonies of B. thuringiensis 0428 are fast-growing, appearing on the surface of the beef-extract agar on the second or third day at 26-30ºC. The average cell size is 6.48±0.16 (large diameter) and 2.62±0.06 (small diameter) microns. The study of the physiological and biochemical properties of the isolated strain shown that B. thuringiensis 0428 is able to form acetyl-methyl-carbinol and lecithinase. B. thuringiensis 0428 is not able to form ureases or pigments, as well as to use citrates and galactose. But it is able to use sucrose, glucose, mannose, and salicin as a source of carbon. The strain 0428 has proteolytic activity. The strain is capable of synthesizing an insecticidal crystalline protein Cry1A and β-exotoxin. All these characteristics allow us to identify the isolated entomopathogenic strain 0428 as B. thuringiensis var. thuringiensis.