In vitro evaluation of probiotic properties of yeasts and lactic acid bacteria isolated from ersho samples collected from different parts of Ethiopia

ABSTRACTErsho is an undefined starter culture used for Ethiopian injera production, and it is a good source of yeasts and lactic acid bacteria (LAB). However, few researchers have been done on the characterization of yeasts and LAB from ersho samples as a source of probiotics. The objective of the current work was to isolate and screen yeasts and LAB from ersho samples and in vitro characterization of their probiotic properties. An experimental research design was used. A total of 55 ersho samples were collected. Based on the ersho samples, 220 yeast colonies and 220 LAB colonies were isolated and purified. For the probiotic characterization, three yeasts (4A, 14D, 54A) and three LAB (1A, 13E, and 55A) were chosen. The isolates 4A, 14D, 54A, 1A, 13E, and 55A were identified as Saccharomyces cerevisiae KRSAN1, Saccharomyces cerevisiae JYC2577, Kazachstania humilis, Enterococcus lactis, Lactobacillus paracasei, and Lactobacillus species, respectively. All the isolates showed positive probiotic characteristics. They had very good acid resistance (percentage survival > 80%), high bile salt resistance (percentage survival > 140%), high cell surface hydrophobicity (>40%), high levels of auto-aggregation (>40%), variable co-aggregation with pathogens (ranged between 42% and 72%), variable antimicrobial activity (clear halo zone ranged from 4.0 to 31 mm), and variable antibiotic resistance responses. The results indicated that the ersho samples can be used as yeast and LAB sources for developing food and probiotic starter cultures