Recent findings on Brevibacillus laterosporus toxins and virulence factors

Abstract: Brevibacillus laterosporus is a spore-forming bacterium showing significant biopesticidal potential against insect species in different orders including coleoptera, lepidoptera, diptera and against nematodes and molluscs. A main morphological feature of this microbial species is the typical canoe-shaped parasporal body attached to one side of the spore. Recent genome sequencing and analysis of entompathogenic strains led to the identification of several toxins and virulence factors. Among these, some mosquitocidal toxins, vegetative insecticidal proteins, chitinases, and several polyketides and nonribosomal peptides. Besides, highly conserved proteins from the spore coat canoe-shaped parasporal body complex (SC-CSPB) of entompathogenic strains were reported to be involved in pathogenesis. Whilst different strains show varying degrees of virulence against diverse insect pests, some represent a beneficial component of the intestinal bacterial community of certain species like the honey bee Apis mellifera. Unexpectedly, a strain isolated from honeybees was pathogenic to the house fly Musca domestica. These findings, supporting the development of either mutualistic or pathogenic interactions of this bacterium with diverse insect species, as the result of a coevolutionary process, are here presented and discussed.