Novel Lactic Acid Bacteria from Multi-Age Piglets: In Vitro Probiotic Traits and Antibacterial Effects Against Escherichia coli

Lactic acid bacteria (LAB) are important probiotics that support intestinal health and growth performance in pigs through modulation of gut microbiota and production of antimicrobial compounds. This study aimed to isolate and evaluate LAB with probiotic potential from feces of healthy, antibiotic- and probiotic-free piglets of different ages. Forty-two fecal samples were collected from a farm in Lamphun province, yielding 318 LAB isolates, of which 135 gram-positive, catalase-negative bacilli were characterized for probiotic traits. Only two isolates (PMvet212 and PMvet318) survived at pH 3.1 with a viability loss of less than 1 log CFU/mL; both tolerated 0.3% bile salt, and PMvet212 also survived at 0.5% bile salt. Their hydrophobicity values were 7.85% and 12.38%, re-spectively, indicating low adhesion capacity. Both isolates showed alpha-hemolysis. Cell-free supernatants of these isolates inhibited Escherichia coli from diarrheic piglets and Staphylococcus aureus ATCC6538, with inhibition zones classified as intermediate. These findings indicate that LAB from piglet feces, particularly PMvet212, possess moderate probiotic potential and antibacterial activity, and may serve as candidates for devel-opment as feed additives to promote swine gut health and reduce reliance on antibiotics.