Title: Evaluating probiotic potential of lactic acid bacteria isolated from Ethiopian traditional fermented foods and beverages
Lactic acid bacteria (LAB) can be defined as gram-positive, acid-tolerant, generally non-sporulating, non-respiring, either rod-shaped (bacilli) or spherical (cocci) bacteria that share common metabolic and physiological characteristics. These bacteria are usually found in decomposing animal and plants sources, produce lactic acid as the major metabolic end product of carbohydrate fermentation. They are frequently distributed in traditional fermented foods and beverages and they are known by producing varieties of bioactive compounds which have effective antagonistic activity against food borne pathogens and spoilage microorganism. Lactic acid bacteria are widely used as probiotics in food industry since they are useful in prevention and treatment of diarrheal diseases. Probiotics are live microorganisms which have effective antagonistic activity against food borne pathogens and if administered in adequate amounts which can promote the health of the consumer. Therefore, this study was aimed to evaluate the probiotic property of lactic acid bacteria isolated from some selected Ethiopian traditional fermented foods and beverages. Hence, for this study different types of Ethiopian traditional fermented foods and beverages like( Kotcho, Bulla, Ergo, Shamita, Borde and Bukuri) were collected and transported to Microbiology laboratory (Jimma University, Biology) for isolation and characterization, evaluation of antimicrobial and probiotic property of LAB isolates. Isolation and characterization of lactic acid bacteria were conducted following their morphological, physiological, biochemical and molecular characterizations and to evaluate the probiotic activity of LAB, the tolerance and survival rate of LAB to different stress condition like low pH, intestinal inhibitor substance, high salt concentration, bile salt, stimulated gastric/ intestinal juice and intestinal inhibitor substance were evaluated. Similarly, antimicrobial activity of LAB isolates were investigated against standard bacteria pathogens; S.aureus, S.Thyphrium, E.coli, P.aurugionsa, K.pnemonia and C. albcans. In this study, totally 125 probiotic lactic acid bacteria were isolated. Out of 125 isolates 54 LAB isolates showed nearby 60-94% of survival rate to low pH(2,2.5 and 3), bile salt (0.3%), intestinal inhibitor substances( phenol, bile, low acidity, pepsin and pancreatic), and stimulated gastro-intestinal environments. The capacity of the isolates to survive acids, intestinal inhibitor substance and stimulated intestinal condition, and bile salt tolerance, effective antagonistic activities help to have good and more effective antagonistic activity against all selected food borne pathogens. All the 54 LAB isolates were resistance to Amplicin, Vancomycin, Gentamycin, Kanamycin, Clindamycin and chloramphenicol, while they were susceptible to Streptomycin and Tetracycline the morphological, biochemical and physiological, carbohydrate utilization characterization and test were performed, accordingly the isolates were grouped under Lactobacillus species(75%), followed by lactococcus and pedioccoccus species. All the isolates, 54 LAB strains, were found to be the most potential Lactic acid bacteria and they were selected as potential probiotic LAB that can be applied as best starter culture and bio-preservative for the enhancement food shelf life. On other hands, the outcome of these studied parameters were used as input data for a principal component analysis (PCA) to select the most promising isolate and the isolates were identified through 16S rDNA sequencing. This study provided a basis for the selection of antimicrobial peptides and the development and utilization of LAB for their potential antimicrobial activity and probiotic activity.