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Isolation and characterization of four plasmids from Bacillus subtilis
Journal of Bacteriology
|March 1, 1977
Summary
Four Bacillus subtilis strains from type cultures contained plasmids, which are circular DNA molecules. These plasmids varied in size and were classified into three types using restriction enzymes, though no antibiotic resistance was observed.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Plasmids are extrachromosomal DNA elements found in bacteria.
- Bacillus subtilis is a well-studied bacterial species with diverse genetic capabilities.
- Investigating plasmid presence is crucial for understanding bacterial genetics and potential applications.
Purpose of the Study:
- To screen Bacillus subtilis isolates for the presence of covalently closed circular deoxyribonucleic acid (DNA) molecules.
- To characterize the identified plasmids in terms of size and restriction enzyme digestion patterns.
- To determine if plasmid-harboring strains exhibit specific phenotypic traits like antibiotic resistance.
Main Methods:
- Cesium chloride-ethidium bromide density gradient centrifugation was used to detect covalently closed circular DNA.
- Plasmid DNA was isolated and analyzed for molecular weight.
- Restriction endonucleases (EcoRI, HindIII, BamNI) were employed to digest plasmid DNA.
- Agarose gel electrophoresis was performed to analyze digestion patterns and classify plasmid types.
Main Results:
- Four out of nineteen Bacillus subtilis strains harbored covalently closed circular DNA molecules (plasmids).
- Two strains (IFO3022, IFO3215) contained a similar plasmid of approximately 5.4 x 10^6 daltons.
- The other two strains (IAM1232, IAM1261) carried plasmids of 4.9 x 10^6 and 5.3 x 10^6 daltons, respectively.
- Plasmid DNA digestion by restriction enzymes resulted in three distinct electrophoretic patterns, classifying them into three types.
- No antibiotic resistance or bacteriocin production was observed in the plasmid-carrying strains.
Conclusions:
- The study successfully identified and characterized plasmids in a subset of Bacillus subtilis isolates.
- The characterized plasmids represent distinct types based on size and restriction enzyme digestion.
- The absence of antibiotic resistance or bacteriocin production suggests these plasmids may not confer these specific traits in the examined strains.