Tracking of Antibiotic Resistant Gene Transfer from a Known Donor to Unknown Recipients in the Simulator of the Human Intestinal Microbial Ecosystem (SHIME)

Introduction: Transfer of antimicrobial resistant genes from contaminated food to the resident microbiota of the GI tract may pose a clinical concern. Knowing which are the donors and/or recipients involved in this gene transfer is problematic as the gut microbiota consists of 500-1,000 species of bacteria. Thus, to determine the potential bacteria capable of horizontal gene transfer in this environment is of interest.

Purpose: The present study employed the Simulator of the Human Intestinal Microbial Ecosystem (SHIME) as a model to evaluate gene transfer from a known donor to unknown recipients in fecal culture pool. 

Methods: The SHIME system was set up following Van den Abbeele et al. (2010) with modification. E. coli O157:H7 carrying a plasmid containing lux gene and kanamycin and ampicillin resistant genes was introduced into the SHIME. Selective pressure (kan, 50 µg/ml) was applied to induce horizontal gene transfer among the microbes. Luminescence was used to track gene transfer.

Results: An unknown luminescent bacterium was isolated and identified as Pseudomonas aeruginosa using the Riboprinter. PCR and restriction analysis of bacterial DNA confirmed the presence of the lux gene and the same plasmid as in the E. coli O157:H7 donor.

Significance: This study employed luminescence as an indicator to track antibiotic resistance gene transfer among resident gut flora. In addition, our study also established a direct relationship between gene donor and gene recipient in the simulated gut model.