DNA walking strategy to identify unauthorized genetically modified bacteria in microbial fermentation products

Area of Science:

• Food safety and microbiology
• Genetically modified organisms (GMOs)
• Antimicrobial resistance (AMR)

Background:

• Unauthorized genetically modified microorganisms (GMM) carrying antimicrobial resistance (AMR) genes have been found in food and feed.
• Whole-genome sequencing (WGS) is used to detect GMM but requires prior microbial isolation, which is challenging.
• A bottleneck exists in detecting GMM due to the difficulty of isolating strains.

Purpose of the Study:

• To develop a culture-independent method for detecting unauthorized GMM in food and feed.
• To overcome the limitations of traditional GMM detection methods that rely on microbial isolation.
• To ensure the traceability and safety of the food and feed chain.

Main Methods:

• Screening for the aadD gene (AMR) and the pUB110 shuttle vector.
• Utilizing DNA walking methods to characterize flanking regions of the pUB110 vector.
• Sequencing amplicons to identify unnatural associations of sequences indicative of GMM.

Main Results:

• The developed culture-independent strategy successfully detected GMM contaminations.
• Unnatural associations of sequences were identified, confirming the presence of unauthorized GMM.
• The method proved effective in analyzing commercialized microbial fermentation products.

Conclusions:

• A novel culture-independent approach effectively detects GMM in food and feed.
• This method bypasses the need for microbial isolation, simplifying GMM detection.
• The strategy enhances the safety and traceability of the food and feed supply chain.