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Plasmid in Bacillus pumilus and the enhanced sporulation of plasmid-negative variants
Abstract:
Approximately 3% of the deoxyribonucleic acid (DNA) of Bacillus pumilus NRS576 can be isolated as covalently closed, circular duplex molecules of homogeneous size. The mol wt of the 576 plasmid is approximately 30 million. NRS576 (plasmid(+)) is oligosporogenic; less than 1% of the cells form spores during incubation in liquid AK sporulation medium. Variants that form spores at a high frequency (greater than 50% spores in 24 h) occur spontaneously at a frequency of approximately 10(-5). More than 25 such variants have been examined and all lack detectable plasmid DNA. A relationship appears to exist between the oligosporogenic properties of NRS576 and the presence of the 576 plasmid.
Insights
The Bacillus pumilus 576 plasmid is linked to its inability to form spores. Spontaneous variants lacking this plasmid exhibit high-frequency sporulation, suggesting a key role for the plasmid in spore formation.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Bacillus pumilus NRS576 contains a plasmid (576 plasmid) comprising approximately 3% of its total DNA.
- This strain is oligosporogenic, with less than 1% of cells forming spores under standard conditions.
Purpose of the Study:
- To investigate the role of the 576 plasmid in the sporulation of Bacillus pumilus NRS576.
- To determine if the presence or absence of the plasmid correlates with sporulation efficiency.
Main Methods:
- Isolation and characterization of plasmid DNA from Bacillus pumilus.
- Spontaneous mutation screening for high-frequency sporulation variants.
- Comparative analysis of plasmid content in sporulating and non-sporulating strains.
Main Results:
- The 576 plasmid has a molecular weight of approximately 30 million.
- Spontaneous variants exhibiting high-frequency sporulation (over 50% in 24 hours) were isolated at a frequency of approximately 10^-5.
- All examined high-frequency sporulation variants (over 25) lacked detectable plasmid DNA.
Conclusions:
- A strong correlation exists between the presence of the 576 plasmid and the oligosporogenic nature of Bacillus pumilus NRS576.
- The absence of the 576 plasmid is associated with high-frequency spore formation in Bacillus pumilus.