Probiotic potential of 'lactobacilli' isolated from traditionally fermented Ethiopian honey wine (Tej)

Probiotics are live microorganisms with health benefits. Lactic acid bacteria (LAB) are among the well-known probiotic formulations in various products intended for human or animal consumption. Prior researches on Tej have thus far looked into its physicochemical compositions, microbial load and starter cultured development. This work on screening of probiotic from Tej is novel because there hasn't been any report on screening of probiotics for improvement of the beverage. The aim of this research is therefore to investigate the probiotic properties of LAB isolated from Tej. Samples were collected from Addis Ababa, and LAB were identified following morphological, physiological, and Matrix Assisted Laser Desorption Ionization Time of Flight Mass spectrometer (MALDI-TOF). A total of 300 isolates were purified and characterized among which 280 of them were LAB. All the 280, LAB isolates were screened for their antibacterial properties out of which 200 showed antibacterial activities, 158 were tolerant to low pH values (pH 2 and 3), 134 survived the bile concentrations of 0.3%, 0.4%, and 1%, and 64 had better adhesion properties. The LAB isolates with adhesion properties were tested for their safety (hemolytic activity) and 18 isolates that had no hemolytic activity were used for further analysis. Each probiotic feature was assessed using standard protocols. The percentage survival (mean ± SD) of the LAB ranged from 5.04 ± 0.05 to 65.47 ± 0.08 and 11.05 ± 0.06 to 70.48 ± 0.04% at pH 2.0 and 3.0, respectively. A statistically significant difference (p < 0.05) was observed in the mean percentage survival at pH 2 and pH 3. The percentage survival (mean ± SD) of the LAB isolates to bile concentrations of 0.3%, 0.5%, and 1% ranged from 21.74 ± 0.08 to 92.48 ± 0.03, 23.84 ± 0.05 to 72.02 ± 0.03 and 30.22 ± 0.16 to 65.37 ± 0.05, respectively. For 77% of the isolates the mean survival was higher at the lowest bile concentration compared to the highest bile concentration and the differences were statistically significant (p < 0.05). The mean cell surface hydrophobicity of the LAB was in the range of 24.11 ± 0.85 to 76.71 ± 0.66%. The antioxidant ability of the LAB based on DPPH (2,2-Diphenyl-1-picrylhydrazyl) radical scavenging ranged from 0.4 to 68.9%, and cholesterol assimilation from 1.6 to 19.4%. Variabilities in the patterns of resistance to antibiotics were observed among the strains of LAB with the most frequent resistance to vancomycin. The LAB isolates with in vitro probiotic potentials that didn't exhibit hemolytic activities were identified as Levilactobacillus brevis (ST1, ST2, ST17), Lecticaseibacillus paracasei (ST3, ST8, ST10, ST11, ST12, ST13, ST14, ST15, ST16, ST18), Lentilactobacillus hilgardii (ST4, ST5, ST6) and Lentilactobacillus parabuchneri (ST7) using the MALDI-TOF MS. In conclusion, LAB with potential probiotic properties have been identified from the Ethiopian traditionally fermented honey wine Tej, further study on the in vivo probiotic potential and whole genome analysis needs to be done to ascertain the safety of the identified potential probiotics.