Isolation, characterization and safety assessment of probiotic lactic acid bacteria from metata ayib (Traditional spiced cottage cheese)

Abstract

BackgroundConsumption of fermented foods and beverages has health benefits; fermented milk products in particular are thought to contain probiotics. The purpose of this study was to characterize probiotic property of lactic acid bacteria isolates from metata ayib. MethodsStandard method with MRS agar was used to isolate and purify LAB isolates from metata ayib. Purified LAB colinies were characterized for its probiotic property using tests for tolerance at low pH (3.0, 2.5, and 2.0), bile salt (0.5% and 0.3%), adherence (Congo red), antagonistic activity, and antibiotic susceptibility. Finally, morphological and physiological tests were used to identify LAB colonies with putative probiotic properties. ResultsA total of 80 LAB isolates were isolated and purified. The majority of isolates, 67 (83.75%), had bacilli shapes, and 59 (73.75%) were homofermentative. All 80 (100%) isolates were tolerated at pH 3.0 treated for three hours; but only 6 (7.5%) isolates were survived at pH 2.0. After 0.3% and 0.5% bile salt treatment for 24 h, all 6 (7.5%) LAB isolates survived above 92.09 ± 0.18 and 83.39 ± 0.21%, respectively. All the 6 isolates were identified as Lactobacillus species; and all were hydrophobicity positive. K. pneumoniae was resistant but S. aureus was sensitive to all of six identified LAB isolates cell free supernatant. All 6 isolates were ciprofloxacin, chloramphenicol, cotrimoxazole and erythromycin-sensitive. Vancomycin resistance was present in four isolates. All these six Lactobacilli species were non-hemolytic, non-biogenic amine producing, and gelatin hydrolysis negative. ConclusionThus, Lactobacilli species isolated from metata ayib may be used as the suitable candidates of probiotics, and bio-therapeutics agents against bacterial infection to humans.