Autochthonous lactic acid bacteria isolated from pig faeces in Thailand show probiotic properties and antibacterial activity against enteric pathogenic bacteria

Lactic acid bacteria (LAB) play an important role in pig health and performance that arises from their beneficial impacts on the balance of gastrointestinal microbes, ability to fight enteric pathogens, and capacity to support the immune system. The aim of this study was to evaluate the functional and safety aspects of five previously isolated autochthonous LAB strains, (Lactobacillus plantarum 22F, 25F and 31F, Pediococcus acidilactici 72N and Pediococcus pentosaceus 77F) from pig faeces as potential probiotics for a pig feed supplement. The functional and safety properties of the strains were assessed by in vitro tests. The functional properties tested were their abilities in tolerating low pH values under simulated gastric conditions, their cell surface properties (hydrophobicity, auto- and co-aggregation), antibacterial activity against the common enteric pathogenic bacteria in pigs (such as pathogenic Escherichia coli, Salmonella Choleraesuis and Streptococcus suis), and diacetyl production. The safety of the strains was analyzed based on the absent of haemolysis on blood and bile salt hydrolase activity. Although all strains demonstrated diacetyl production, good survivability and antibacterial activities, L. plantarum 22F and 25F showed the best performance with the strongest antibacterial actions against the indicator pathogens. Of the strains, only P. pentosaceus 77F exhibited haemolysis or bile salt hydrolase activity. Furthermore, a principal component analysis revealed that L. plantarum 22F possessed superior functional and safety aspects compared to the other four autochthonous strains and to reference strains L. plantarum JCM 1149 and P. acidilactici DSM 20284. Further in vivo studies using oral administration of the strains are justified to assess their effectiveness as feed supplements for pigs.