ANTIBACTERIAL ACTIVITY AND PRESERVATIVE PROPERTIES OF PROBIOTIC LACTOBACILLUS SPECIES FROM FERMENTED DRINKS

Fermented beverages such as Palm wine (Elaeis guineensis) and Burukutu (Sorghum bicolor) are integral to the Nigerian diet and are often associated with health benefits due to beneficial bacteria like Lactobacillus. This study evaluated the antibacterial activity and preservative properties of probiotic Lactobacillus sp. isolated from fermented drinks. Six locally fermented drink samples (palm wine=3 and burukutu=3) were purchased in Ota, Nigeria. The nutritional contents of the fermented drinks were determined by analysing the protein, carbohydrate, and lipid contents. Lactobacillus species were isolated and identified using morphological, biochemical, and Analytical Profile Index (API 50 CHL). The antibacterial activity of the cell-free supernatant (CFS) of the screened probiotic lactobacilli was tested against spoilage and pathogenic bacterial isolates. Also, the preservative potential and bioactive profiling of the selected Lactobacillus CFS were determined. The result showed that the ash (5-24%), carbohydrate (25-29%), and moisture content (37-93%) of Burukutu and Palm wine samples was significantly high in all the fermented drink samples (P> 0.05). A total of six Lactobacillus spp. Including L. plantarum (BB05), L. acidophilus (B006), L. plantarum (PB03), L. fermentum (BA01), L. fermentum (BB06), L. acidophilus (PA03) were isolated from the fermented drink samples. The probiotic activity of Lactobacillus sp. showed that isolates PB03, BO06, and BB06 exhibited a high survival rate (109-187%) pH 2, bile (1.0%), and phenol (1%), respectively, indicating the isolates' ability to tolerate low pH and bile salts in the gastrointestinal tract. For the antibacterial activity of Lactobacillus spp. cell cultures against isolated spoilage bacteria, BBO6, PB03, and BA01, showed significant inhibition (7-25mm%), against P. putida (p>0.05), while for Lactobacillus spp. CFS BB06 showed significant inhibition against all isolated spoilage bacteria and PA03 except for P.fluorescens (p>0.05). All Lactobacillus CFS isolates showed substantial inhibitory activity against E. coli (p>0.05). PB03, BA01, and BB06 showed significant zones against all reference strains. Meat treated with Lactobacillus CFS showed delayed spoilage and maintained quality for up to 48 hours at room temperature (BB06, BA01, PB03, and BO06), contrary to the untreated control at room temperature. The metabolites detected in the CFS of L. fermentum, L. plantarum, and L. acidophilus were 2,4-Di-tert-butylphenol, Benzoic acid, 4-nitroso-, ethyl ester, and n-Hexadecanoic acid. Hence, Lactobacillus species from fermented drinks could be an effective source of antibacterial metabolites with preservative ability for food products.