Probiotic Potential of Enterococcus faecium Isolated from Chicken Cecum with Immunomodulating Activity and Promoting Longevity in Caenorhabditis elegans

Abstract

Probiotics, including <i>Enterococcus faecium</i>, confer a health benefit on the host. An <i>Enterococcus</i> strain was isolated from healthy chicken cecum, identified as <i>E. faecium</i> by 16S rDNA gene sequence analysis, and designated as <i>E. faecium</i> L11. To evaluate the potential of <i>E. faecium</i> L11 as a probiotic, the gastrointestinal tolerance, immunomodulatory activity, and lifespan extension properties of the strain were assayed. <i>E. faecium</i> L11 showed >66% and >62% survival in artificial gastric juice (0.3% pepsin, pH 2.5) and simulated small intestinal juice (0.5% bile salt and 0.1% pancreatin), respectively. Heat-killed <i>E. faecium</i> L11 significantly (<i>p</i> < 0.05) increased immune cell proliferation compared with controls, and stimulated the production of cytokines (IL-6 and TNF-α) by activated macrophages obtained from ICR mice. In addition, <i>E. faecium</i> L11 showed a protective effect against <i>Salmonella</i> Typhimurium infection in <i>Caenorhabditis elegans</i>. In addition, feeding <i>E. faecium</i> L11 significantly (<i>p</i> < 0.05) extended the lifespan of <i>C. elegans</i> compared with the control. Furthermore, genes related to aging and host defense were upregulated in <i>E. faecium</i> L11-fed worms. In conclusion, <i>E. faecium</i> L11, which prolongs the lifespan of <i>C. elegans</i>, may be a potent probiotic supplement for livestock.