Cloning vehicles for the homologous Bacillus subtilis host-vector system

Area of Science:

• Molecular Biology
• Microbial Genetics

Background:

• Bacillus subtilis is a key organism in industrial biotechnology.
• Efficient genetic manipulation tools are crucial for B. subtilis research and development.
• Existing cloning systems may have limitations in efficiency or selection mechanisms.

Purpose of the Study:

• To construct and characterize novel Bacillus subtilis plasmids for enhanced DNA cloning.
• To develop a homologous cloning system utilizing specific chromosomal regions.
• To establish a reliable method for identifying recombinant plasmids via insertional inactivation.

Main Methods:

• Construction of B. subtilis plasmids carrying leu and/or dihydrofolate reductase (DHFR) regions.
• Introduction of a trimethoprim resistance (tmpr) gene into plasmids.
• Characterization of plasmid pTL12 for DNA fragment cloning at specific restriction sites (BamHI, EcoRI, BglII, XmaI).
• Assessment of insertional inactivation of the leuA gene upon DNA insertion.

Main Results:

• Plasmids conferring trimethoprim resistance (Tmp) were successfully constructed.
• Plasmid pTL12 demonstrated utility for cloning DNA fragments at multiple restriction sites.
• Insertional inactivation of the leuA gene was observed at BamHI and XmaI sites, while tmpr remained functional.
• A selection strategy for recombinant plasmids using Leu-Tmpr colonies was established.

Conclusions:

• The pTL12 plasmid, in combination with B. subtilis 168, provides an efficient homologous cloning system.
• The insertional inactivation of leuA offers a straightforward method for detecting recombinant plasmids.
• This system facilitates the cloning of DNA fragments in Bacillus subtilis, advancing genetic engineering efforts.