This study examined the isolation, phenotypic characterization, and antimicrobial properties of lactic acid bacteria (LAB), with emphasis on Lactobacillus species, in palm sap samples obtained from the Nigerian Institute for Oil Palm Research (NIFOR). Out of nine palm sap samples analyzed, seven yielded cultivable microorganisms, confirming palm sap as a rich natural source of beneficial bacteria. Seven Lactobacillus isolates were identified based on morphological, biochemical, and physiological characteristics. All isolates exhibited typical LAB traits, including Gram-positive rod morphology, catalase and oxidase negativity, fermentation of glucose and lactose, motility, and tolerance to bile salts—an essential probiotic attribute. Variations in sugar fermentation profiles indicated phenotypic diversity among the isolates. Antimicrobial activity of the isolates was assessed against Salmonella spp., Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus. Results obtained using McFarland turbidity standardization revealed varying inhibitory effects. Isolate GO7 consistently showed broad-spectrum, concentration-independent antimicrobial activity, highlighting its probiotic potential. Although GO3 initially demonstrated strong inhibition, its activity declined after standardization, indicating a concentration-dependent effect. All isolates survived bile salt exposure, suggesting potential resilience within the gastrointestinal environment. While GO3 exhibited the highest bile tolerance, GO7 maintained the most consistent antibacterial performance. Isolate GO5 also showed promising antimicrobial activity, particularly against Listeria monocytogenes. Overall, the findings emphasize the importance of standardized evaluation in assessing probiotic potential and identifying palm sap as a valuable source of functional Lactobacillus strains.
OBARISIAGBON et al. (Tue,) studied this question.