Evaluation of Enterococcus strains newly isolated from Egyptian sources for bacteriocin production and probiotic potential

Screening for bacteriocin-producing lactic acid bacteria (LAB) showing probiotic properties is of high significance due to their applications in food, and health fields. Hence, the aim of the current study was to isolate, identify, and study the in vitro probiotic properties, antimicrobial and antioxidant activities of LAB isolates obtained from Egyptian sources. Out of 79 isolated bacteria, 53 isolates were selected as potential LAB and their antimicrobial activities were investigated. Seven out of them (isolates 33, 34, and 35 from feces of Nile Lechwe, and isolate 42 from feces of Grant's zebra) exhibited wide antimicrobial spectra, which were caused by a proteineous compound that were suggested to be bacteriocin. These isolates are nominated as potential probiotic strains due to their high pH tolerance and good thermal stability. Moreover, they exhibited high in vitro antioxidant activities by recording 84.47 ± 1.83, 86.84 ± 0.93, 82.37 ± 1.11, and 83.16 ± 0.84% DPPH scavenging activity, respectively. Furthermore, isolates 33, 34, and 35 showed high in vitro hydrophobic properties, which reached 93.93 ± 0.83, 87.75 ± 1.75, and 80.20 ± 1.40%, respectively. Isolates were identified using 16S rRNA sequencing as Enterococcus faecium except for isolate 10, which was classified to Enterococcus hirae. These results nominated Egyptian sources as a promising repository for potent LAB. This is the first study describing bacterial isolates from Egyptian zoo samples as potential bacteriocin producers, possible probiotic strains, and antioxidant agents,. Further studies are encouraged to evaluate the in vivo potency of these isolates for future application as antioxidant dietary supplements for feeding and treatment of human and animals.