AUTHOR=Biggel Michael , Etter Danai , Corti Sabrina , Brodmann Peter , Stephan Roger , Ehling-Schulz Monika , Johler Sophia 

TITLE=Whole Genome Sequencing Reveals Biopesticidal Origin of Bacillus thuringiensis in Foods

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.775669

DOI=10.3389/fmicb.2021.775669

ISSN=1664-302X

ABSTRACT=<p><italic>Bacillus thuringiensis</italic> is a microbial insecticide widely used to control agricultural pests. Although generally regarded as safe, <italic>B. thuringiensis</italic> is phylogenetically intermingled with the foodborne pathogen <italic>B. cereus sensu stricto</italic> and has been linked to foodborne outbreaks. Limited data on the pathogenicity potential of <italic>B. thuringiensis</italic> and the occurrence of biopesticide residues in food compromise a robust consumer risk assessment. In this study, we analyzed whole-genome sequences of 33 <italic>B. thuringiensis</italic> isolates from biopesticides, food, and human fecal samples linked to outbreaks. All food and outbreak-associated isolates genomically matched (≤ 6 wgSNPs; ≤ 2 cgSNPs) with one of six biopesticide strains, suggesting biopesticide products as their source. Long-read sequencing revealed a more diverse virulence gene profile than previously assumed, including a transposase-mediated disruption of the promoter region of the non-hemolytic enterotoxin gene <italic>nhe</italic> and a bacteriophage-mediated disruption of the sphingomyelinase gene <italic>sph</italic> in some biopesticide strains. Furthermore, we provide high-quality genome assemblies of seven widely used <italic>B. thuringiensis</italic> biopesticide strains, which will facilitate improved microbial source tracking and risk assessment of <italic>B. thuringiensis</italic>-based biopesticides in the future.</p>