BACKGROUND Bacillus thuringiensis (Bt) is a Gram-positive bacterium that produces various insecticidal proteins used to control insect pests. Spodoptera frugiperda is a global insect pest which causes serious damage to crops, but bio-insecticides currently available to control this pest have limited activity and so new ones are always being sought. In this study we have tested the hypothesis that a biomarker for strain toxicity could be found that would greatly facilitate the identification of new potential products. RESULTS Using genomic sequencing data we constructed a linkage network of insecticidal genes from 1957 Bt genomes and found that four gene families, namely cry1A, cry1I, cry2A and vip3A, showed strong linkage. For 95 strains isolated from soil samples we assayed them for toxicity towards S. frugiperda and for the presence of the above gene families. All of the strains that showed high toxicity also contained a member of the vip3A gene family. Two of them were more toxic than a commercially available strain and genomic sequencing identified a number of potentially novel toxin-encoding genes. CONCLUSIONS The presence of a vip3A gene in the genome of a Bt strain proved to be a strong indicator of toxicity towards S. frugiperda validating this biomarker approach as a strategy for future discovery programs.

The diverse group of chemicals used in making of plastic is known to be highly toxic and poses a serious threat to the biosphere. These substances besides hitting hard to ecosystem cause an array of problems like birth defects, cancer, damage of nervous and immune systems. The present research work was aimed to isolate and characterize PHB producing bacteria from landfill soil sample collected from Sanehally, Chitradurga district and qualitatively screened by using viable staining techniques. Quantitative estimation was examined by using solvent extraction method. The PHB producing bacteria were characterized based on morphological, biochemical and molecular identification and confirmed as Bacillus thuringiensis strain KUMBNGBT-41 (Accession No. MW040075). Growth parameters were optimized for biomass production using various conditions such as medianutrient broth, incubation time-72hrs, temperature37 & ring;C, pH -7.0, carbon source -glucose, nitrogen sourceammonium chloride and carbon to nitrogen ratio as 4:1. The low-cost production media was used for PHB production by cheaper substrates in submerged fermentation. PHB was analysed and quantified by using UV -Visible spectrophotometer at 200-600nm.