Gene disruption in Salmonella typhimurim by modified λ Red disruption system

Area of Science:

• Bacteriology
• Molecular Biology
• Genetics

Background:

• Gene knockout techniques are crucial for studying bacterial gene function, particularly in Salmonella species.
• Existing methods for gene disruption in Salmonella have limitations.

Purpose of the Study:

• To develop and apply a novel method for disrupting the phoP gene in Salmonella typhimurium.
• To assess the efficacy of combining SOEing PCR and the lambda Red disruption system for gene knockout.

Main Methods:

• Utilized splicing by overlap extension (SOEing) PCR and the lambda Red disruption system.
• Constructed a linear DNA fragment containing upstream and downstream regions of the phoP gene and a Kanamycin resistance cassette (from pKD4 plasmid).
• Electroporated the DNA construct into competent cells of wild type and standard Salmonella typhimurium strains.

Main Results:

• Successfully generated transformant colonies in the standard Salmonella typhimurium strain on LB-Km-agar plates.
• Observed no transformant colonies in the wild type Salmonella typhimurium strain.
• Hypothesized that the lambda Red system's inflexibility or the wild type strain's restriction-modification system hindered transformation.

Conclusions:

• The combined SOEing PCR and lambda Red disruption system is effective for generating phoP mutants in standard Salmonella typhimurium strains.
• The developed construct is potentially applicable for creating phoP mutants in diverse Salmonella species due to conserved gene homology.
• Further investigation is needed to understand the transformation failure in the wild type strain.