Isolation and characterization of anti-Salmonella lactic acid bacteria from the porcine gastrointestinal tract

Aims: To identify lactic acid bacteria (LAB) of porcine intestinal origin with anti-Salmonella activity. Methods and Results: Samples were obtained from pig faeces and caeca and screened for the presence of anti-Salmonella LAB. The 11 most promising isolates were identified as belonging to the genera Lactobacillus and Pediococcus. The LAB exhibited large variation in their ability to survive in simulated gastric juice at pH 1.85. While Lactobacillus johnsonii species survived at levels of 80% for up to 30 min, Lactobacillus pentosus species declined to <0.001% in that time. All isolates tolerated porcine bile at a concentration of 0.3% (w/v), with some isolates capable of growth in the presence of up to 5% (w/v) bile. The ability of the LAB isolates to prevent Salmonella invasion of intestinal epithelial HT-29 cells varied, with reductions of between 30% (Lact. pentosus) and 80% (Lactobacillus murinus spp.) observed. Conclusions: LAB of porcine origin were observed to survive simulated passage through the GIT and inhibit growth of Salmonella and its invasion of the intestinal epithelium. Significance and Impact of the Study: The data demonstrate that some porcine intestinal LAB isolates may offer potential as probiotics for the reduction of Salmonella carriage in pigs.