Two different parasporal inclusions are produced by Bacillus thuringiensis subsp. finitimus.

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Bacillus thuringiensis subspecies produce parasporal inclusions, which are proteinaceous crystals with insecticidal properties.
• The genetic basis for the production of these inclusions can involve both chromosomal and plasmid-borne genes.

Purpose of the Study:

• To investigate the genetic control of two distinct parasporal inclusions produced by Bacillus thuringiensis subsp. finitimus.
• To determine the role of plasmids in the synthesis of these inclusions.

Main Methods:

• Plasmid curing experiments to generate strains lacking specific plasmids.
• Analysis of parasporal inclusion production in plasmid-cured and wild-type strains.
• DNA hybridization to assess gene localization.
• Plasmid transfer experiments to Bacillus cereus.

Main Results:

• Bacillus thuringiensis subsp. finitimus produces two parasporal inclusions: one enclosed within the exosporium and one free.
• Strains cured of plasmids produced only the free inclusion, indicating its gene is chromosomal.
• The 98 MDa plasmid was essential for the production of the enclosed inclusion.
• Transfer of the 98 MDa plasmid to Bacillus cereus resulted in the production of enclosed inclusions.

Conclusions:

• Distinct parasporal proteins in Bacillus thuringiensis subsp. finitimus are synthesized through the coordinated action of chromosomal and plasmid genes.
• The 98 MDa plasmid carries the gene for the enclosed parasporal inclusion protein.