Isolation, Genomic, and Proteomic Characterization of a Novel Neotropical Strain of Bacillus thuringiensis with Mosquitocidal Activities

Abstract

The combination of genomic and proteomic analyses is a useful tool for the study of novel Bacillus thuringiensis (Bt) strains, as these approaches allow the accurate identification of pesticidal proteins and virulence factors produced. Here, we isolated and evaluated the potential of a novel Neotropical Bt strain (TOD651) for controlling larvae of Aedes aegypti and Culex quinquefasciatus mosquitoes. Aiming for the full comprehension of the TOD651 larvicidal potential, we further evaluated the whole TOD651 genome and conducted the proteomic analysis of the TOD651 spore–crystal mixtures. Our results showed that Bt TOD651 similarly killed both A. aegypti (0.011 µg/mL) and C. quinquefasciatus (0.023 µg/mL) larvae, exhibiting similar potency to the commercial Bt strain. The genome sequence revealed that Bt TOD651 harbors cry11Aa3, cry10Aa4, cry4Aa4, cry4Ba5, cyt1Aa5, cyt1Ca1, cyt2Ba13, mpp60Aa3, and mpp60Ba3. The proteomic analysis revealed no expression of Mpp60Aa3, while all the other pesticidal proteins were expressed (Cry4Ba5 was more abundant than Cyt1Aa5). The expression of the Mppe showed the major proportions between proteases. The virulent factor neutral protease B and spore coat proteins were also expressed. The expression of relevant pesticidal proteins (e.g., Cry, Cyt, Mpp, and other pathogenic factors), whose actions can occur in a synergic relation, indicates that the biocontrol using Bt TOD651 may contribute to delaying the selection of resistant individuals.

Isolation of Mosquitocidal Bacteria from Soil Samples to Control Mosquito Vectors

“…quinquefasciatus and An. stephensi (Roy et al, 2021;Alves et al, 2023). Bacillus cereus isolated from fresh water fish Clarias batrachus also showed promising activity against the larvae of Ae.…”

Multiple cry Genes in Bacillus thuringiensis Strain BTG Suggest a Broad-Spectrum Insecticidal Activity

“…It develops in two life cycles: vegetative growth and sporulation. Cry protein crystals are formed during the sporulation phase [ 14 , 15 , 16 , 17 ], which involves seven distinct stages: (1) axial filament formation; (2) formation of the pre-spore septum; (3) parasporin crystals and pre-spore formation; (4–6) formation of exospores, development of the primary cell wall and transformation of spore nucleoids; (7) spore maturation and cell lysis [ 8 ]. Crystals are synthesized after the second stage of sporulation and accumulate in the cell, where they can represent up to 30% of the dry weight of sporulated cells [ 18 ].…”

“…It develops in two life cycles: vegetative growth and sporulation. Cry protein crystals are formed during the sporulation phase [14][15][16][17], which involves seven distinct stages: (1) axial filament formation;…”