In vitro evaluation of probiotic properties of lactic acid bacteria isolated from some traditionally fermented Ethiopian food products

Abstract

Probiotics are live microorganisms which when consumed in large number together with a food promote the health of the consumer. The aim of this study was to evaluate in vitro probiotic properties of lactic acid bacteria (LAB) isolated from traditional Ethiopian fermented Teff injera dough, Ergo and Kocho products. A total of 90 LAB were isolated, of which 4 (4.44%) isolates showed 45.35-97.11% and 38.40-90.49% survival rate at pH values (2, 2.5 and 3) for 3 and 6 h in that order. The four acid tolerant isolates were found tolerant to 0.3% bile salt for 24 h with 91.37 to 97.22% rate of survival. The acid-and-bile salt tolerant LAB isolates were found inhibiting some foodborne test pathogenic bacteria to varying degrees. All acid-and-bile tolerant isolates displayed varying sensitivity to different antibiotics. The in vitro adherence to stainless steel plates of the 4 screened probiotic LAB isolates were ranged from 32.75 to 36.30% adhesion rate. The four efficient probiotic LAB isolates that belonged to Lactobacillus species were identified to strain level using 16S rDNA gene sequence comparisons and namely were Lactobacillus plantarum strain CIP 103151, Lactobacillus paracasei subsp. tolerans strain NBRC 15906, Lactobacillus paracasei strain NBRC 15889 and Lactobacillus plantarum strain JCM 1149. The four Lactobacillus strains were found to have potentially useful to produce probiotic products.

In vitro probiotic and industrial properties of bacteria isolated from fermented food products

“…In vitro investigations have been conducted for the selection of bacteria that have potential probiotic properties including low pH and bile salt tolerance, adhesion to intestinal epithelial cells, production of antimicrobial substances, antibiotic resistance, cell surface hydrophobicity, auto-aggregation, colonisation of intestinal cells, and prevention of pathogens (Jeronymo-Ceneviva et al, 2014;Somashekaraiah et al, 2019;Mulaw et al, 2019;Xu et al, 2020;Shivangi et al, 2020). These properties can be strain-specific, thus differing within the same bacterial species (Klimko et al, 2020).…”

“…For probiotic bacteria, the most significant characteristic is their survival/tolerance to the adverse conditions in the GIT, including gastric acidity (Succi et al, 2005) and bile salts (Chen et al, 2019) to maintain their population (Lakra et al, 2020), and also their viability within the food. These have been commonly studied under simulated physiological conditions (simulated gastric environment) in vitro (Zielińska et al, 2015;Mulaw et al, 2019;Sakandar et al, 2019;Shivangi et al, 2020). According to the draft guidelines for the evaluation of probiotic bacteria in foods which was reported by a joint FAO and WHO working group, resistance to gastric acidity and bile salts are among the currently used in vitro tests for the study of probiotic strains (FAO and WHO, 2002).…”

“…The findings of several in vitro tests that were performed for the selection of potential acid and bile tolerant probiotic strains showed that the strains can survive at different pH values and bile salt concentrations (Melgar-Lananne et al, 2013;Hashemi et al, 2014;Mulaw et al, 2019;Klimko et al, 2020;Won et al, 2020;Xu et al, 2020) as indicated in Table 2, and those strains may differ in survival rates even under the same pH and bile salt conditions (Azat et al, 2016). These tests can also be performed to ensure the quality of probiotic cultures during manufacturing, storage, and throughout the shelf life of the products.…”

“…The probiotic resistance of LAB strains isolated from Armada cheese (Spanish goats' milk cheese) against cefoxitin, oxacillin, vancomycin, teicoplanin, nitrofurantoin, and trimethoprim (Herreros et al, 2005) is a good example. Additionally, Mulaw et al (2019) reported that all the isolates of LAB they tested (E052, E031, T035, and K011) were resistant to kanamycin and streptomycin. Likewise, Oussaief et al (2020) also reported that all the examined strains were resistant to erythromycin and kanamycin, while only the strain LEFS 41 was resistant to ampicillin.…”

“…Competitive niche exclusion of the pathogens in the host GIT and in the foods by the probiotics is one of the possible mechanisms employed in the mitigation strategy (Khaneghah et al, 2020). This shows that the fermented food products that contain probiotics are not only a source of nutrition but also possess functional health benefits to protect the consumers from the risk of foodborne pathogens (Mulaw et al, 2019). Abbasiliasi et al (2017) reported that probiotic strain (P. acidilactici KP10) isolated from traditional dried curd was found to have inhibitory activity against some of the common foodborne pathogens including Listeria monocytogenes ATCC 15313, Salmonella enterica ATCC 13311, Shigella sonnei ATCC 9290, Klebsiella oxytoca ATCC 13182, Enterobacter cloaca ATCC 35030, and Streptococcus pyogenes ATCC 12378.…”