Toxicological and molecular characterization of local Bacillus thuringiensis isolates from soil and insects

M. Harba, I. Idris, H. Ismail

Volume 28, Issue 3;
Pages: 226-232; 2022
ISSN: 2069-0053 (print) (former ISSN: 1453-1399), Agroprint;
ISSN (online): 2068-9551

Previous research has investigated Bacillus thuringiensis (Bt) isolates to control pests that destroy vital crops particularly in Syria. However, novel Bt strains are still needed to be isolated and characterized across the country. A collection of 25 isolates of Bt from Syrian soil and 40 isolates from infected insects exhibit height toxicity have been studied. The study focuses on the isolates that possess high levels of toxicity versus the reference strain Bt. kurstaki HD-1. In order to determine the most toxic isolates, five isolates from soil SSy60-b, SSy111-c, SSy125-c, SSy126-c, SSy141-c, and five isolates from infected insects SyG46, SyG41, SyG43, SyG30-a, SyE3-S were tested. The Lethal Concentration 50 (LC₅₀) of the spore-crystal mixture ranged from 2.7 mg. g ^-1 to more than 15.6 mg. g ^-1. A PCR test with a specific primer that is recognizing regions of the cry genes was used to analyze the present of cry genes in the isolates with the most toxic effects. Among all the studied isolates, the Bt SYG46 has exhibited the highest level of toxicity, therefore, it seems to be promising to be implemented in pest control programs against main economical lepidoptera pest.