Probiotic Bacteria Engineered to Produce Lactoferrin Peptides Protected Chickens From Infection | Research

The takeaway

A probiotic bacterium engineered to produce lactoferrin antimicrobial peptides fought off E. coli infection in chickens, boosted their immune response, and restored gut health — offering an antibiotic alternative for poultry farming.

No antibiotic resistance genes
The engineered probiotic was designed without antibiotic resistance markers, addressing a key safety concern for use in food-producing animals

What the researchers found

Researchers engineered a probiotic bacterium (Lactococcus lactis) to produce lactoferrin antimicrobial peptides (lactoferricin and lactoferrampin) and fed it to chickens. The engineered probiotic inhibited pathogenic E. coli (APEC-O78) and Staphylococcus aureus in vitro, and when added to chicken feed it improved growth performance, boosted immune markers (serum IgG, intestinal SIgA), suppressed pro-inflammatory cytokines (IL-1β, IL-12, IFN-γ, TNF-α), and restored gut microbiome balance disrupted by infection.

The construct was designed without antibiotic resistance genes and included a fluorescent marker for tracking — addressing safety concerns about engineered probiotics entering the food chain.

Why it matters

Antibiotic-resistant bacteria from livestock can spread to humans through food and the environment. Replacing antibiotics with antimicrobial peptide-producing probiotics could break this transmission cycle. This study demonstrates a practical delivery system — engineering food-grade bacteria to continuously produce antimicrobial peptides in the gut — that could reduce antibiotic use in the poultry industry while maintaining animal health.

The numbers in context

Inhibited APEC-O78 and S. aureus in vitro · Increased serum IgG and intestinal SIgA · Suppressed IL-1β, IL-12, IFN-γ, TNF-α · Improved average daily intake and gain-to-feed ratio · Restored gut microbiome (16S rDNA) · No antibiotic resistance genes

How the study worked

Researchers constructed a recombinant L. lactis MG1363 strain expressing bovine lactoferricin and lactoferrampin peptides with an mCherry fluorescent marker and no antibiotic resistance gene. In vitro antimicrobial activity was tested against APEC-O78 and S. aureus. Chickens were fed the engineered probiotic and then challenged with APEC-O78. Outcomes measured included growth performance, serum IgG, intestinal SIgA, inflammatory cytokines, and gut microbiome composition via 16S rDNA sequencing.

Who was studied

Chickens challenged with avian pathogenic E. coli O78

What this study cannot tell us

This is a poultry study — results may not translate directly to mammalian or human applications of lactoferrin peptides. The specific number of chickens and statistical details were not provided in the abstract. Long-term safety of feeding engineered probiotics to food animals and potential environmental release are not addressed. The applicability to human gut health is indirect.

How to read the evidence

This is preliminary evidence from a chicken infection model. The study demonstrates proof of concept for probiotic-delivered antimicrobial peptides with multiple positive outcomes, but the lack of detailed statistical reporting in the abstract and the animal-only context limit the evidence grade.

When this study was published

Published in 2025, this is very current research in the rapidly growing field of engineered probiotics and antimicrobial peptide alternatives to antibiotics in agriculture.

The bigger picture

This study sits at the intersection of three hot research areas: antimicrobial peptides as antibiotic alternatives, engineered probiotics as drug delivery systems, and the fight against antibiotic resistance in food animal production. The approach — using food-grade bacteria as living factories for antimicrobial peptides — could be adapted beyond poultry to other livestock and potentially human health applications. Lactoferrin peptides are already well-characterized in human health research, making this a translatable platform.

Questions still open

Could the same L. lactis delivery platform be adapted to produce antimicrobial peptides for human gut health applications?
How does continuous peptide production by a gut probiotic compare to bolus dosing of synthetic antimicrobial peptides?
What happens to the engineered bacteria if they escape into the environment — can they transfer genetic material to other organisms?

Common questions

What are lactoferrin peptides and why are they used as antibiotics?

Lactoferricin and lactoferrampin are short peptide fragments of lactoferrin, a protein found in milk and other body fluids. They kill bacteria by disrupting their cell membranes, while also reducing inflammation and boosting immune function — making them promising natural alternatives to conventional antibiotics.

Why engineer bacteria to produce antimicrobial peptides instead of just adding the peptides to feed?

Synthetic peptides are expensive and get degraded quickly in the gut. By engineering a food-safe probiotic to continuously produce the peptides directly in the gut, the bacteria act as a living drug factory — delivering fresh antimicrobial peptides right where they're needed, at a fraction of the cost.

Read the original research

Oral-Delivery Lactococcus lactis expressing cherry fusion lactoferrin peptides against infection of avian pathogenic Escherichia coli in chickens.

Poultry science, 104(1), 104637

View on PubMed ↗Publisher’s paper ↗

Citation

Li, Zhuoran; Wang, Xueying; Zheng, Dianzhong; Han, Fuzhen; Li, Yue; Zhou, Han; Li, Jiaxuan; Cui, Wen; Jiang, Yanping; Wang, Xiaona; Xie, Weichun; Tang, Lijie. (2025). Oral-Delivery Lactococcus lactis expressing cherry fusion lactoferrin peptides against infection of avian pathogenic Escherichia coli in chickens.. Poultry science, 104(1), 104637. https://doi.org/10.1016/j.psj.2024.104637