Strategy to Detect Genetically Modified Bacteria Carrying Tetracycline Resistance Gene in Fermentation Products

Unexpected contaminations of unauthorized genetically modified microorganisms (GMM) harbouring antimicrobial resistance (AMR) genes in food and feed enzymes, additives and flavourings commercialized on the European market have recently alerted the competent authorities regarding the food and feed safety. At the control level, we have therefore proposed a PCR-based strategy as first line screening targeting GMM carrying AMR genes in order to help enforcement laboratories. The potential presence of frequently used AMR genes is first investigated, using real-time PCR. In case of a suspicious matrix, the full-length of the detected AMR genes is then determined, using conventional PCR followed by Sanger sequencing, allowing to support the competent authorities in their evaluation related to potential health risks. In this study, PCR methods targeting an additional key AMR gene, being the tet-L gene (GenBank: D00946.1) conferring a resistance to tetracycline, were developed and successfully assessed in terms of specificity, sensitivity and applicability. In integrating these PCR methods, the proposed PCR-based strategy, initially targeting two key AMR genes conferring a resistance to chloramphenicol (GenBank: NC_002013.1) and kanamycin (GenBank: M19465.1), is consequently strengthened, allowing the coverage of a larger spectrum of potential GMM contaminations in microbial fermentation products.