In vitro Characterization of Lactic Acid Bacteria from Fruits and Medicinal Plants for Probiotic Potential

Eighty-four bacterial isolates obtained from fruits and medicinal plant leaves were screened for probiotic potential. Twenty-eight lactic acid bacteria (LAB) demonstrated strong tolerance to simulated gastrointestinal conditions, with >80% survivability at pH 2, >45% at pH 3, and >65% survival in 0.3% bile salt. These isolates were further evaluated for antimicrobial activity against Staphylococcus aureus and Escherichia coli, of which five strains (JM3, BAN1, BAN5, KIW3, and TL4) exhibited moderate antagonistic effects. Antibiotic susceptibility profiling revealed predominantly intermediate resistance patterns, consistent with previously reported probiotic LAB, indicating acceptable safety characteristics. Phytase activity was detected in two strains, with BAN1 showing the highest activity, suggesting potential to enhance mineral bioavailability. Morphological and biochemical characterization identified all five selected isolates as Gram-positive, catalase-negative, rod-shaped bacteria belonging to the genus Lactobacillus. Based on their acid–bile tolerance, antimicrobial activity, antibiotic susceptibility profile, and phytase production, strains JM3 and BAN1 emerged as the most promising candidates. These findings indicate their potential application in functional foods and fermented products, warranting further molecular identification and in vivo validation.