In Vitro Evaluation of Probiotic Potential and Safety Assessment of Lactobacillus mucosae Strains Isolated from Donkey’s Lactation

The study, for the first time, reports the efficacy, safety and probiotic properties of two Lactobacillus mucosae strains, Lact. mucosae SRV5 and Lact. mucosae SRV10 isolated from donkey milk. All major in vitro screening assays were employed to evaluate studied strains. Both strains displayed good survivability at gastric pH 2.0, 0.3% bile and simulated oro-gastrointestinal fluid (above 88%). Also, cultures demonstrated good cell surface hydrophobicity and auto-aggregation ability, clearly indicating their effective cell adhesion ability. Furthermore, functional attributes for both strains demonstrated their efficient bile salt hydrolase and cholesterol-reducing ability in spent broth. In addition to this, both strains expressed significant DPPH-radical scavenging ability of both culture supernatant and intact cells. Another auxiliary health benefit exhibited by both these strains is their antimicrobial potential against 18 enteric and 5 multidrug-resistant clinical pathogens with significant inhibition zone size. Extracellular enzyme production such as lipase, amylase, protease and esterase was also studied. Detailed safety evaluation study showed the presence of innate antibiotic resistance and absence of haemolysis, DNAse and gelatinase activity in both the strains. Also, none of the strains possessed toxic mucinolytic activity in mucin degradation assay. To conclude, both donkey milk isolates, Lact. mucosae SRV5[Accession number: MK990014] and Lact. mucosae SRV10 [Accession number: MN064860], exhibited excellent probiotic ability with tolerance to simulated oro-gastrointestinal fluids, cellular hydrophobicity, auto-aggregation, bile salt hydrolase, cholesterol reduction, high antioxidant activity and antimicrobial potential especially against multidrug-resistant pathogens.