A pangenomic study of Bacillus thuringiensis.

Area of Science:

• Microbiology
• Genomics
• Bacteriology

Background:

• Bacillus thuringiensis (B. thuringiensis) is a soil bacterium known for its plasmid-encoded toxins (Cry), utilized as biopesticides.
• Understanding the genomic structure of B. thuringiensis is essential for its application and evolutionary studies.

Purpose of the Study:

• To perform a pangenomic analysis of Bacillus thuringiensis using next-generation sequencing.
• To characterize the genomic diversity and variation within B. thuringiensis isolates.
• To compare the pangenome characteristics of B. thuringiensis with related species.

Main Methods:

• Sequencing of seven B. thuringiensis isolates with high coverage and base-quality.
• Pangenome analysis to determine core and unique gene content.
• Comparative genomics to assess pangenome openness and identify variation hotspots.

Main Results:

• The B. thuringiensis pangenome comprises an estimated 4196 core genes and 558 unique genes.
• B. thuringiensis exhibits an open pangenome, similar to B. cereus but distinct from the closed pangenome of B. anthracis.
• Extensive genomic divergence was observed, with hotspots for variation in specific genomic regions (2.3-2.8Mb and 5.0-5.6Mb).
• Orthologous genes showed high identity (>84.5%).

Conclusions:

• High-coverage sequencing assemblies are valuable for pangenomic studies, even before complete gap closure.
• The open pangenome of B. thuringiensis suggests continuous acquisition of genetic material.
• Genomic variations and hotspots identified can inform future research on B. thuringiensis evolution and function.