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Plasmid maintenance in Bacillus stearothermophilus is strain-dependent
1Department of Genetics, Centre of Biological Sciences, Haren, Netherlands.
FEMS Microbiology Letters
|June 15, 1992
Summary
Plasmid stability in Bacillus stearothermophilus varies by strain and replication mechanism. The pTB913 plasmid is unstable in strain CU21 but stable in NUB3621, making the latter suitable for molecular cloning.
Area of Science:
- Microbiology
- Molecular Biology
- Biotechnology
Background:
- Plasmids are crucial tools in molecular biology for gene cloning and expression.
- Rolling-circle replication plasmids, like pTB913, are derived from thermophilic Bacillus species.
- Understanding plasmid stability is essential for effective use in host organisms.
Purpose of the Study:
- To investigate the segregational stability of pTB913-based plasmids in different Bacillus stearothermophilus strains.
- To evaluate the suitability of a specific host-vector system for molecular cloning applications.
- To compare the stability of rolling-circle and theta replication plasmids in thermophilic bacteria.
Main Methods:
- Construction of pTB913 derivatives based on the rolling-circle plasmid pTB19.
- Testing plasmid stability in Bacillus stearothermophilus strains CU21 and NUB3621 at 57°C.
- Quantification of single-stranded plasmid DNA.
- Assessment of a RepA-based theta-replicating plasmid in B. stearothermophilus NUB3621.
Main Results:
- Plasmid stability was found to be strain-dependent in Bacillus stearothermophilus.
- High levels of single-stranded pTB913 DNA correlated with instability in strain CU21 at 57°C.
- Low single-stranded DNA levels in strain NUB3621 resulted in slight instability of pTB913 derivatives at 57°C.
- A RepA-based theta replicon was highly unstable in B. stearothermophilus NUB3621.
Conclusions:
- The NUB3621 strain is a suitable host for pTB913-based plasmids, offering a stable system for molecular cloning.
- Rolling-circle replication plasmids exhibit variable stability influenced by host strain and DNA replication intermediates.
- Theta replication mechanisms may confer instability in thermophilic Bacillus hosts.
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