Novel Insights into the isolation and <i>in vitro</i> probiotic characterization of <i>Weissella confusa</i> from Navara Rice in Kerala, India

Fermented foods are important reservoirs of probiotic lactic acid bacteria (LAB), which confer health benefits by modulating gut microbiota. Navara, a medicinal rice from Kerala, India, valued in Ayurveda, is an underexplored source of these bacteria. This study aimed to isolate, identify, and conduct the first in-vitro probiotic characterization of LAB from fermented Navara rice. A bacterial isolate was obtained on MRS agar and identified via 16S rRNA gene sequencing as Weissella confusa strain PK18202456.1. Its probiotic potential was evaluated using standard in vitro assays. The isolate demonstrated strong antagonistic activity against enteric pathogens (e.g., 12 mm zone vs. MRSA), robust coaggregation (76.67% with E. coli), and high cell-surface hydrophobicity (93.92% at 4 h). It survived simulated gastrointestinal stress, tolerating pH 3.0 and 0.3% bile salts, and exhibited bile salt hydrolase activity (22.7 ± 2.5 mm zone). Antibiotic profiling showed susceptibility to ampicillin, tetracycline, erythromycin, and clindamycin, with resistance to vancomycin and gentamicin. This work provides the first evidence for the isolation and comprehensive probiotic characterization of a Weissella confusa strain from Navara rice, establishing it as a promising candidate for future functional food applications.