Purification of High-Molecular-Weight Antibacterial Proteins of Insect Pathogenic Brevibacillus laterosporus Isolates

Brevibacillus laterosporus (Bl) is a Gram-positive and spore-forming bacterium belonging to the brevis phylogenetic cluster. Globally, insect pathogenic strains of have been isolated, characterised, some activities patented. Two isolates, Bl 1821L 1951, exhibiting pathogenicity against diamondback moth mosquitoes, are under development as biopesticide in New Zealand. However, due suspected activity putative antibacterial proteins (ABPs), endemic isolates often grow erratically. Various purification methods, including size exclusion chromatography, sucrose density gradient centrifugation, polyethylene glycol precipitation, ammonium sulphate precipitation employed this study, enabled isolation two ~30 ~48 kD from one protein 1951. Purification uninduced cultures 1951 also yielded bands on SDS-PAGE, which indicated their spontaneous induction. A disc diffusion assay was used determine antagonistic ABPs. Subsequent transmission electron microscope (TEM) examination purified protein-containing solution showed presence encapsulin (~30 kD) polysheath (~48 kD)-like structures. Although only both structures were seen strain TEM. Furthermore, while assessing fractions chromatography method, population persister cells noted. Overall, work added wealth knowledge about high-molecular-weight (HMW) (bacteriocins) bacteria Bl.