Probiotic potential and safety analysis of lactic acid bacteria isolated from Ethiopian traditional fermented foods and beverages

Abstract

Background Probiotics are live microorganisms that effectively combat foodborne pathogens, promoting intestinal health when consumed in sufficient amounts. This study evaluated the probiotic potential and safety of lactic acid bacteria isolated from selected Ethiopian traditional fermented foods and beverages (Kotcho, Bulla, Ergo, Cabbage-Shamita, Borde, and Bukuri). To assess the isolates’ probiotic activity, tolerance, and survival rate under various stressful conditions, including low pH, intestinal inhibitory substances, salt concentration, bile salt, and simulated gastric/intestinal juice. The isolates were also tested for antagonistic activities against common bacterial and fungal pathogens (Staphylococcus aureus, Salmonella Typhimurium, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Candida albicans) and safety (auto-aggregation, co-aggregation, cell source hydrophobicity, hemolytic activity, DNase, and antibiotic susceptibility). The best probiotic lactic acid bacteria (LAB) were characterized to species level following standard MALDI TOF/mass spectrometry analysis. Results A total of 125 potentially probiotic LAB were isolated of which 17 (13.60%) isolates survived low pH (2, 2.5, and 3), bile salt (0.3%), intestinal inhibitory chemicals (phenol, bile, low acidity, pepsin, and pancreas), and simulated gastro-intestinal settings with near 60–94% survival rate. In addition, 11 best LAB isolates were further screened based on additional screening including their antimicrobial efficacy, preservative efficiency, bacteriocin production besides resistance to low acid and bile salts, and survival potential under simulated gastrointestinal conditions. All 11 LAB isolates were resistant to ampicillin, vancomycin, gentamicin, kanamycin, clindamycin, and chloramphenicol, while they were susceptible to streptomycin and tetracycline. The MALDI TOF mass spectrometry analysis result of efficient probiotic LAB grouped them under the genus Pediococcus, Enterococcus, and Lactococcus including Pediococcus pentosaceus, Enterococcus faecium, Lactococcus lactis, and Pediococcus acidilactici. Conclusion Ethiopian traditional fermented foods and beverages are good sources of promising probiotic lactic acid bacteria. These isolates could serve as potential starter cultures and bio-preservative for the enhancement of the shelf life of foods. This study established the groundwork for the selection of excellent probiotics for the development and application of LAB for antibacterial action, starter culture production, and preservation activities.