How Two Tiny Bacteria Are Revolutionizing Poultry Farming
For decades, the poultry industry has relied on antibiotics to keep chickens healthy and growing efficiently. But this practice has come at a cost—the alarming rise of antibiotic-resistant "superbugs" that threaten both animal and human health. As concerns mounted, scientists raced to find sustainable alternatives that could deliver similar benefits without the dangerous side effects. Their search led them to an unexpected solution: harnessing the power of beneficial bacteria that already exist in nature. Enter Lactobacillus reuteri and Streptomyces coelicolor—two unlikely microbial heroes that are transforming how we raise broiler chickens and offering a glimpse into the future of sustainable farming.
Limosilactobacillus reuteri (commonly known as Lactobacillus reuteri) is a Gram-positive bacterium that naturally inhabits the gastrointestinal tracts of many animals, including humans, pigs, and chickens 4 . For years, scientists have recognized its potential as a probiotic—a "good" bacterium that confers health benefits on its host.
What makes L. reuteri particularly remarkable is its ability to produce powerful antimicrobial substances including lactic acid, hydrogen peroxide, and a broad-spectrum antimicrobial compound called reuterin 4 .
Reuterin is exceptionally effective against a wide range of harmful microorganisms including gram-positive and gram-negative bacteria, fungi, and even protozoa 4 . This makes L. reuteri a formidable opponent against common poultry pathogens like E. coli and Salmonella 4 .
If L. reuteri is the guardian of the gut, Streptomyces coelicolor is the master chemist of the soil. This filamentous, Gram-positive bacterium belongs to the Actinobacteria class and has long been celebrated for its incredible biochemical capabilities 2 .
For nearly a century, scientists have known that Streptomyces species produce life-saving antibiotics—in fact, nearly half of all known antibiotics originate from this genus 2 .
S. coelicolor is particularly prolific, producing at least five different secondary metabolites with four exhibiting antimicrobial activity: the blue-pigmented actinorhodin, reddish undecylprodigiosin, methylenomycin, and the calcium-dependent antibiotic 2 .
In an ambitious 8-week study conducted in 2021, researchers set out to systematically evaluate the effects of L. reuteri and S. coelicolor on broiler chicken growth performance 1 2 . The research team designed a comprehensive experiment involving 240 one-day-old chicks randomly assigned to four different dietary treatments in a completely randomized design 1 2 :
Standard broiler diet with no probiotics
60 birdsStandard diet supplemented with 100 ppm of L. reuteri
60 birdsStandard diet supplemented with 100 ppm of S. coelicolor
60 birdsStandard diet with a mixture of both probiotics (50 ppm each)
60 birdsTo ensure the bacteria would survive storage and reach the chickens' gastrointestinal tract intact, the researchers used an encapsulation technique 2 . The bacteria were first cultured, then centrifuged and added to a sterile soy protein and alginate solution. This mixture was then introduced to sterile calcium chloride solution, forming stable microcapsules that protected the probiotic bacteria until consumption 2 .
| Group Name | Number of Birds | Probiotic Supplementation | Delivery Method |
|---|---|---|---|
| Control | 60 | None | Standard feed |
| L. reuteri | 60 | 100 ppm L. reuteri | Encapsulated in feed |
| S. coelicolor | 60 | 100 ppm S. coelicolor | Encapsulated in feed |
| Combination | 60 | 50 ppm of each probiotic | Encapsulated in feed |
When the data were analyzed at the end of the eight-week study, the results revealed significant differences between the groups. Chickens that received the combination of L. reuteri and S. coelicolor showed the most impressive outcomes, demonstrating a 2% improvement in body weight gain compared to the control group 1 . But the benefits didn't stop there—these birds also consumed 7% less feed and showed a 6-7% improvement in feed conversion ratio (FCR), meaning they required less feed to produce each pound of body weight 1 .
While the individual probiotics also showed benefits, the synergistic effect of combining them was particularly noteworthy. The research suggested that L. reuteri and S. coelicolor could be used effectively either separately or in combination, depending on which performance metrics farmers prioritize 1 .
The implications of these findings extend far beyond a single research study. With the global poultry industry seeking sustainable alternatives to antibiotics, these results offer a promising solution that aligns with both economic and public health priorities. The improved feed efficiency translates to direct cost savings for farmers, while reducing reliance on antibiotics addresses the critical threat of antimicrobial resistance.
| Performance Metric | Control Group | L. reuteri Only | S. coelicolor Only | Combination Group |
|---|---|---|---|---|
| Body Weight Gain | Baseline | Improved vs. control | Improved vs. control | +2% vs. control |
| Feed Consumption | Baseline | No significant change | No significant change | -7% vs. control |
| Feed Conversion Ratio | Baseline | Improved vs. control | Improved vs. control | 6-7% improvement |
The promising results in broiler chickens prompted researchers to investigate whether similar benefits could be achieved in other poultry species. In a 2025 study focusing on French guinea fowls, researchers used a similar experimental design with 216 day-old "keets" (young guinea fowls) 7 . The birds were divided into the same four treatment groups, with probiotics added to the feed at concentrations of 10⁸ CFU/g for individual treatments and 10⁴ CFU/g each for the combination group 7 .
The results mirrored what had been observed in broiler chickens. Guinea fowls fed diets containing L. reuteri showed improved feed consumption during the 3-8 week period, while those receiving both probiotics demonstrated a significantly lower feed conversion ratio at 2 and 8 weeks of age 7 . Although body weight gains didn't differ significantly among groups, the improved feed efficiency—particularly in the combination group—reinforced the potential of these probiotics across different poultry species.
| Research Finding | Broiler Chickens | French Guinea Fowls |
|---|---|---|
| Improved body weight gain | 2% improvement in combination group | No significant difference |
| Reduced feed consumption | 7% decrease in combination group | Improved feed consumption with L. reuteri |
| Enhanced feed conversion ratio | 6-7% improvement in combination group | Significantly lower FCR at key time points |
| Recommended application | Individual or combined, depending on goals | Effective individually or in combination |
While the concept of probiotics seems straightforward, developing effective probiotic supplements requires sophisticated tools and techniques. Here are some key components of the probiotic researcher's toolkit:
Function: Creates protective microcapsules that shield probiotic bacteria from environmental stresses, ensuring they survive storage and reach the intestinal tract intact 2 .
Function: Provides optimal nutrients for growing and maintaining Lactobacillus strains before encapsulation 5 .
Function: Used in the encapsulation process to form stable gel microcapsules through ionic cross-linking 2 .
Function: Serves as a precursor for reuterin production when metabolized by L. reuteri 5 .
The compelling research on L. reuteri and S. coelicolor represents more than just another feed additive—it signals a fundamental shift in how we approach animal health and nutrition. By harnessing the power of naturally occurring bacteria, scientists have developed a solution that addresses one of the most pressing challenges in modern agriculture: how to maintain healthy, productive livestock without contributing to the antibiotic resistance crisis.
As research continues to uncover new insights into the complex relationship between gut microbiota and animal health, the potential applications of probiotics continue to expand. From reducing pathogenic infections to improving nutrient absorption and enhancing overall animal welfare, these microscopic workhorses are proving that sometimes the biggest solutions come in the smallest packages.
The transition from antibiotic-dependent farming to a more natural, probiotic-based approach won't happen overnight, but the scientific foundation has been firmly established. As more farmers adopt these technologies and researchers refine their applications, the poultry industry moves closer to a future where sustainable practices and economic viability go hand-in-hand—all thanks to two remarkable bacteria and the scientists who discovered their potential.