Engineered Probiotic E. coli Strain Shows Promise in Reducing Salmonella in Poultry
Researchers have engineered a modified E. coli Nissle 1917 probiotic strain that outcompetes Salmonella for intestinal adhesion in chickens and turkeys, significantly reducing pathogen carriage in animal trials. The strain was built using a Salmonella-derived type 1 fimbrial gene that confers high adherence to host cells, and was designed without antibiotic resistance genes to avoid contributing to antimicrobial resistance. If validated in further studies, the approach could offer a novel tool to reduce Salmonella contamination in poultry and lower rates of human foodborne illness.
Salmonellosis remains one of the leading causes of foodborne illness in the United States, with poultry meat and eggs serving as primary transmission vehicles due to Salmonella carriage in chicken intestinal microbiomes. Despite longstanding USDA food safety priorities and years of research, conventional approaches have not achieved meaningful control of Salmonella in poultry flocks. In this study, researchers identified a type 1 fimbrial allele from Salmonella that confers exceptionally high adherence to host cells, then introduced those genes into E. coli Nissle 1917 — an FDA-designated Generally Regarded As Safe (GRAS) probiotic strain used in human medicine. The engineered strain was designed with an antibiotic-free plasmid maintenance system, addressing a key concern about introducing antibiotic resistance genes into agricultural settings. In laboratory assays, the modified probiotic adhered to tissue culture cells at higher levels than Salmonella itself, and in live animal trials it significantly reduced Salmonella intestinal colonization in broilers, laying hens, and turkeys. The competitive exclusion mechanism — where the probiotic occupies intestinal adhesion sites before Salmonella can — represents a departure from antibiotic-based interventions. The findings are currently available as a preprint on bioRxiv and have not yet undergone formal peer review.
What's missing
The study's own key limitations and open questions include: the work is a preprint and has not yet been peer-reviewed; the specific dosing regimens, timing of probiotic administration, and long-term colonization stability in commercial flock conditions are not fully characterized; it is unclear whether the engineered strain persists or spreads in the environment after use; regulatory pathways for approval of a genetically engineered probiotic in commercial poultry production are not discussed; and the study does not address whether the approach is effective against all clinically relevant Salmonella serovars.
What different sources said
- bioRxivCenter
Engineering a Hyper-Adherent E. coli Nissle Probiotic Strain that Reduces Intestinal Carriage of SalmonellaPathogens in Poultry
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