Evaluation of Plasmid Stability by Negative Selection in Gram-negative Bacteria

Area of Science:

• Molecular Biology
• Genetics
• Biotechnology

Background:

• Plasmid stability is crucial for biotechnological applications.
• Current methods using antibiotic resistance are insensitive to highly stable plasmids.

Purpose of the Study:

• To develop a novel, highly sensitive assay for measuring plasmid stability.
• To overcome the limitations of existing positive selection assays.

Main Methods:

• Utilized an aph-parE cassette with a rhamnose-inducible promoter.
• Engineered bacteria to synthesize ParE toxin upon rhamnose induction, leading to cell death.
• Selected for plasmid-free cells after toxin-induced elimination.

Main Results:

• The novel assay successfully measures plasmid stability with high sensitivity.
• Demonstrated elimination of plasmid-containing cells using the rhamnose-inducible system.
• Confirmed plasmid absence using kanamycin resistance.

Conclusions:

• The developed assay provides a sensitive method for assessing plasmid stability.
• This technique is valuable for studying and engineering highly stable plasmids.
• The aph-parE system offers a robust tool for plasmid stability analysis.