ESTIMATION OF PRODUCTIVITY BACILLUS THURINGIENSIS ON DIFFERENT MEDIA

Abstract

Aim: Studying the nutrient medium influence on productivity and insecticidal activity of entomopathogenic bacteria Bacillus thuringiensis (Bt). Materials and methods. The reference exotoxin strain B. thuringiensis var. thuringiensis (Bt H1) 800 and selective strain (Bt H1) 87 were used. The common nutrient medium, such as: meat infusion agar, Luria Bertrani (LB), and optimized laboratory–industrial medium: yeast-polysaccharidic composition, technological medium of molasses (4.0%) was used for cultivation. During the development optimal cultivation conditions there were determined the following parameters: producing capacity pure culture through boundary dilutions, the rate of formation entomocidal metabolites by percentage of biotest deaths – larvae of Leptinotarsa decemlineata Say. Results. It was shown the different technological effect and expression of entomopathogenic activity in different media – from 1.6 to 3.3 billion spores / ml, and from 85.0 to 96.8%, in accordance. Additionally, a high crystal endotoxin productivity was observed in the yeast polysaccharidic medium in comparison with common media. Expressive maximum death of larvae (L1-2) is detected on the 10-th day of the experiment on infection load of 1: 1. Conclusions. The most conduced interrelation was protein-vitamin complex to cornmeal 2: 1 (3.0 and 1.5% in accordance). This ensures the highest titer of entomocidal components in Bt cultures – 2.8 and 3.3 billion spores/ml.