Biochemical and molecular characterization of Bacillus spp. isolated from insects

Abstract

In the present study two isolates of bacteria from insect cadavers were characterized by 16S rRNA, protein profiling, biochemical, antibiotic sensitivity and evaluated for insecticidal activity against Aphis gossypii. Isolates VKK-AC1, VKK-SL1 identified as Bacillus thuringiensis (Bt), B. subtilis (Bs) respectively through 16S rRNA sequencing. SDS–PAGE analysis reveals that two isolates shows protein pattern range of 20-245 kDa. Both the strains were positive to catalase, nitrate, citrate, glucose, argenine and negative reaction with Voges-proskauers. Bt VKK-AC1, Bs VKK-SL1 and one reference Bt strain (Btk HD1) were sensitive to antibiotics which act on protein synthesis viz., streptomycin, tetracycline and resistant to ampicillin, pencillin G. Toxicity studies revealed that isolates Bt VKK-AC1 and HD1 were most effective in trypsinized form whereas Bs VKK-SL1 was found to be effective in pre-solubilized form (90% mortality). The present study shows that potential of B. subtilis besides Bt as biocontrol agent for successful management of insect pests.