Isolation and characterization of probiotic lactic acid bacteria from fermented traditional rice for potential applications in food and livestock production

Probiotic lactic acid bacteria (LAB) are widely used in fermented food products and as feed additives for livestock, poultry, and fish. Fermented rice presents significant potential as an alternative carrier for probiotics. Therefore, this study aimed to isolate, identify, and characterize potential probiotic LAB strains from fermented traditional rice cultures. After primary isolation on De Man, Rogosa, and Sharpe (MRS) agar, presumptive isolates were first phenotypically characterized using Gram staining, catalase assay, endospore staining, and motility tests. Preliminary phenotypic tests identified 48 isolates as presumptive LAB. 16S rRNA sequencing analysis confirmed the presence of five species; Lacticaseibacillus casei, Lacticaseibacillus paracasei , and Lacticaseibacillus rhamnosus , notably, Schleiferilactobacillus harbinensis , and Liquorilactobacillus vini were identified for the first time in fermented rice. In the biochemical characterization, none of the isolates produced H 2 S, and all exhibited a homofermentative glucose utilization pattern. The majority (71 %) demonstrated detectable growth at 15 °C and 45 °C and tolerated NaCl concentrations up to 6.5 %. Regarding probiotic potential, the isolates were sensitive to widely used therapeutic antibiotics and exhibited strong antimicrobial activity against Staphylococcus aureus, Escherichia coli, Salmonella enteritidis , and Candida glabrata . They also showed bile tolerance up to 0.3 % (w/v) and possessed milk coagulation ability. Our findings suggest these LAB strains have potential for use in fermented foods and livestock feed due to their probiotic properties, including antimicrobial activity, bile tolerance, and milk coagulation. They may serve as natural alternatives to antibiotics and additives, but further in vivo studies are needed to confirm their efficacy and stability.