Probiotic Potential of Lactiplantibacillus plantarum Isolates from Indonesian Kefir Grains Cultured in Goat Milk

Background: The increasing interest in functional fermented dairy products has intensified research on lactic acid bacteria (LAB) as potential probiotics. Kefir, a symbiotic matrix of LAB and yeasts, represents a rich source of probiotic microorganisms, yet limited data exist on strains isolated from Indonesian goat milk kefir. Exploring the molecular identity and probiotic traits of these local isolates can contribute to the development of novel functional dairy cultures suited to regional production systems. Methods: Sixteen LAB isolates were procured from Indonesian kefir grains sub-cultured in goat milk and evaluated for probiotic characteristics. Molecular identification was conducted via 16S rRNA sequencing and in vitro experiments assessed acid and bile salt tolerance, carbohydrate utilization with 4% inulin and antibacterial efficacy against Staphylococcus aureus, Escherichia coli and Salmonella Typhi. Statistical analysis was conducted to ascertain strain-level variations in probiotic characteristics. Result: Twelve isolates were successfully identified, including eight Lactiplantibacillus plantarum and four Lactobacillus plantarum strains. Strains AN and QF showed high acid tolerance ( greater than 50% survival at pH 2.0 for 90 min) and strain NT exhibited strong bile salt resistance up to 1.5% (log 6.5 CFU/mL). All isolates metabolized inulin as the sole carbon source and inhibited pathogenic bacteria with inhibition zones of 3.7-6.0 mm, the strongest against S. aureus. L. plantarum strains obtained from goat milk kefir exhibited strong probiotic properties, validating their suitability as starting cultures for functional dairy fermentation and as possibilities for industrial probiotic formulations.