Development of a Novel Probiotic Strain with Digestion Functionality, Lacticaseibacillus paracasei JL32-5 from...

Several Lactobacillus strains isolated from fermented food are expected to possess digestion supporting function as potential probiotics. However, the safety of Lactobacillus as functional food and its stability until consumption are often overlooked. To prevent potential side effects and maximize probiotic efficacy, it is essential not only to demonstrate the beneficial properties of candidate strain but also verify their safety and stability through a stepwise method. In this study, Lactobacillus strains were isolated from various fermented food and sequentially evaluated for safety, stability, and probiotic properties with a focus on digestive activity. First, five safety tests were conducted in accordance with WHO/FAO guidelines-antibiotic minimum inhibitory concentrations (MICs), hemolytic activity, bile salt hydrolase (BSH) activity, D-/L-lactate production, and cytotoxicity based on lactate dehydrogenase (LDH) released from human epithelial cells. Next, four stability tests were performed, including tolerance to heat, oxygen, and gastric acid/bile salts. In addition, adhesion ability to intestinal epithelial cells was examined as an indicator of colonization potential. Finally, probiotic properties related to assistance of digestion-lipase activity, protease activity, lactose and xylan utilization ability—were evaluated. Through this three-step evaluation, Lacticaseibacillus paracasei JL32-5 was proven to be a safe and stable probiotic resource supporting digestion of lipid, protein, lactose, and non-digestible carbohydrate therefore enhancing human wellness.