Bacillus subtilis generates a major specific deletion in pAM beta 1

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• pAM beta 1 is a 26.5-kilobase plasmid originally isolated from Streptococcus faecalis.
• Plasmids can be transferred between bacterial species via conjugation.
• Understanding plasmid behavior in different hosts is crucial for genetic engineering and microbial studies.

Purpose of the Study:

• To investigate the conjugal transferability of the plasmid pAM beta 1 between Streptococcus lactis and Bacillus subtilis.
• To analyze genetic alterations in pAM beta 1 after transfer and replication in B. subtilis.
• To assess the impact of these alterations on the plasmid's transferability.

Main Methods:

• Conjugal transfer experiments were performed between S. lactis and B. subtilis.
• Restriction and Southern blot analyses were used to detect deletions in the plasmid DNA.
• Hybridization experiments were conducted to investigate potential chromosomal integration of deleted fragments.

Main Results:

• pAM beta 1 was successfully transferred from S. lactis to B. subtilis, but not vice versa.
• Plasmids reintroduced into S. lactis after cycling through B. subtilis lost transferability to Streptococcus cremoris.
• Restriction and Southern blot analyses revealed a major 10.6-kilobase deletion and several minor deletions in pAM beta 1 maintained in B. subtilis.

Conclusions:

• Bacillus subtilis induces specific deletions in the pAM beta 1 plasmid.
• These deletions, particularly the major one, render the plasmid non-transferable under certain conditions.
• Minor deletion derivatives may utilize alternative origins of replication in B. subtilis.