Evaluation of Probiotic Properties of Lactic Acid Bacteria Isolated from Some Fermented Foods

Abstract

Probiotics are live microorganisms which when consumed in adequate quantity; promote the health of the consumer. This study was carried out to evaluate probiotic properties of lactic acid bacteria (LAB) isolated from fermented foods (wara, ogi, orange juice, pickles, sauerkraut and grape juice). A total of eighty four isolates were identified as LAB species by morphological, Gram staining and short biochemical tests. All isolates were characterized for probiotic properties including NaCl tolerance, bile tolerance, sugar fermentation, proteolytic activity, acid tolerance, antibiotic susceptability assay and adherance to stainless plates. All isolates survived in 2%, 4%, 6.5% and 8% NaCl concentrations. Four isolates were tolerance to pH 1.5, 2.0, and 3.0 for 24 and 48 hours. The four acid tolerant isolates were found to tolerant 0.3% bile salt for 24 hours with 85 to 99% rate of survival. Results of fermentation test showed that most isolates fermented all sugars. All strains digested casein by producing protease enzyme in skim milk agar plate. All the four isolates were found inhibiting some pathogenic bacteria to varying degrees and also displayed varying susceptibility to different antibiotics. The in vitro adherence to stainless steel plates of the 4 screened isolates were ranged from 32.83 to 37.70% adhesion rate. The phylogenetic analysis and the 16S rDNA sequencing assigned all the four efficient LAB isolates with probiotic properties to genus Lactobacillus, Leuconostoc and Weissella and were identified as Lactobacillus plantarum, Lactobacillus plantarum, Leuconostoc mesenteriodes and Weissella paramesenteroides. The four LAB strains were found to be potentially useful to produce probiotic products. Further study is needed to find specific probiotics with specific benefit from fermented foods.