Isolation and Evaluation of Probiotic Potential of Lactic Acid Strains From Healthy Equines for Potential Use in Salmonella Infection.
Authors: Pei Lulu, Yang Hao, Qin Songkang, Yan Ziyin, Zhang Hui, Lan Yanfang, Li Aoyun, Iqbal Mudassar, Shen Yaoqin
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Researchers isolated four lactic acid bacterial strains—two *Pediococcus acidilactici* and two *Lactobacillus equi*—from the faeces of healthy horses and assessed their viability under simulated gastrointestinal conditions and their capacity to inhibit common equine pathogens including *Salmonella typhimurium*, *E. coli*, *Staphylococcus aureus*, and *Pasteurella multocida*. Whilst all strains were eliminated at gastric pH 2.0, they demonstrated differential survival at pH 3.0–4.0 and maintained viable populations when exposed to artificial gastrointestinal fluid and temperatures between 37–55°C, suggesting reasonable resistance to the upper digestive tract environment. Safety profiling revealed all isolates were non-haemolytic with no adverse effects on mice at doses of 1 × 10⁹ CFU/day, and critically, mice given lower preventative doses (1 × 10⁸ CFU/day) of strains P1 or L1 showed substantially reduced diarrhoea incidence and mortality following *Salmonella* challenge compared to controls. These findings indicate that specific equine-derived lactic acid bacteria merit further investigation as potential probiotics for mitigating salmonellosis risk, though practitioners should note that gastric pH and delivery method will likely influence efficacy in living horses, and strain-specific variations in pathogen inhibition suggest that probiotic efficacy cannot be assumed across different bacterial isolates.
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Practical Takeaways
- •Equine-derived lactic acid bacteria strains show promise as oral probiotics to reduce clinical salmonellosis risk and severity, particularly for prevention strategies
- •These strains tolerate gastrointestinal pH and bile conditions sufficiently to reach the intestine where they exhibit broad-spectrum antimicrobial activity
- •Further development and in-vivo equine safety/efficacy trials are warranted before clinical application, as current data are from mouse models
Key Findings
- •Four lactic acid strains (2 Pediococcus acidilactici, 2 Lactobacillus equi) isolated from healthy horses survived pH 3.0-4.0 but not pH 2.0, with higher survival at pH 4.0
- •All isolates demonstrated inhibitory activity against Salmonella typhimurium, E. coli, Staphylococcus aureus, and Pasteurella multocida
- •Mice preventatively gavaged with P1 or L1 at 1×10⁸ CFU/day showed significantly lower diarrhea rates and mortality following Salmonella challenge compared to controls
- •All strains were γ-hemolytic and showed no adverse effects on mouse health at 1×10⁹ CFU/day, suggesting safety for probiotic use