Study compares three pig-derived lactic acid bacteria strains

A newly posted study in Animals compares three porcine-derived lactic acid bacteria strains as possible probiotic tools for swine production, with Lactiplantibacillus plantarum MRS002 and Ligilactobacillus salivarius MRS004 emerging as the strongest in vitro performers. The work assessed growth behavior, acid production, tolerance to simulated gastric acid and bile salts, and genome characteristics, aiming to identify strains that could be developed for pig-specific probiotic use. (preprints.org)

The backdrop is familiar to veterinarians working in food animal practice: pressure to reduce reliance on antibiotics in livestock has intensified interest in probiotics, especially strains derived from the target host species. Reviews of swine probiotic development consistently note that host origin, survival through gastric acid and bile exposure, antimicrobial activity, and compatibility with large-scale production are core selection criteria. Earlier pig-focused studies have also argued that human-derived screening approaches may not translate well to porcine physiology, making host-specific strain selection more relevant for eventual on-farm use. (porcinehealthmanagement.biomedcentral.com)

In the new comparison, all three strains showed anaerobic growth and acid-producing capacity, but performance diverged under stress conditions. At low pH, L. plantarum MRS002 and L. salivarius MRS004 had significantly higher survival than L. amylovorus MRS003 at pH 2.0. The same pattern held in bile salt testing: L. plantarum and L. salivarius maintained high survival in 0.1% to 0.3% bile salt, while L. amylovorus showed a sharp drop in survival at concentrations of 0.3% and above. The authors conclude that all three strains have promising in vitro probiotic traits, but with clear strain-specific differences in stress tolerance and functional potential. (preprints.org)

The genomic data add another layer. KEGG annotation linked more than 50% of genes in each strain to metabolism, including 52% in L. plantarum MRS002, 54% in L. amylovorus MRS003, and 50% in L. salivarius MRS004. The paper frames those findings as evidence of active metabolic capacity typical of probiotic lactic acid bacteria, and as a starting point for understanding how individual strains may differ in nutrient use, stress response, and gut function. That matters because probiotic effects in pigs are highly strain-specific, even within the same species. (preprints.org)

There doesn’t appear to be outside expert commentary on this specific paper yet, but the broader field supports the study’s direction. A 2023 Animals paper from Anhui Agricultural University similarly screened pig-derived lactic acid bacteria and identified only a subset of isolates as strong candidates after testing growth, tolerance, hydrophobicity, and pathogen inhibition. Reviews in Porcine Health Management and Applied Microbiology and Biotechnology likewise stress that in vitro screening is necessary, but not sufficient: promising strains still need validation for colonization, safety, stability, and real-world efficacy in pigs. (mdpi.com)

Why it matters: For veterinary professionals, this is a useful early-stage signal rather than a practice-changing result. The study helps refine which porcine-derived lactobacilli may be worth advancing into feed additive development, particularly as swine systems continue to evaluate non-antibiotic tools for gut health and production support. But the findings are limited to laboratory assays and genome analysis. They don’t yet show whether these strains improve average daily gain, reduce diarrhea, alter antimicrobial use, or deliver consistent benefits across weaning, finishing, or disease-challenge settings. (preprints.org)

Another practical point is formulation. A strain that looks strong in acid and bile tests still has to survive manufacturing, storage, transport, and feed delivery, then perform consistently in the microbiologic complexity of commercial barns. That’s one reason the swine probiotic literature keeps emphasizing not just biologic plausibility, but host specificity, safety, and production feasibility. In that context, L. plantarum MRS002 and L. salivarius MRS004 may now have a clearer case for follow-up work than L. amylovorus MRS003. (porcinehealthmanagement.biomedcentral.com)

What to watch: The key next milestone is in vivo validation—controlled pig studies that test these strains for safety, gut colonization, pathogen suppression, growth performance, and compatibility with commercial feed systems before any meaningful veterinary or industry adoption can follow. (porcinehealthmanagement.biomedcentral.com)