Enterococci as Intestinal Microbiota: Investigation of Characteristics and Probiotic Potential in Isolates from Adults and Breast-Fed Infants

• Published in: Probiotics and antimicrobial proteins 2022-12, Vol.14 (6), p.1139-1150
• Main Authors: Rahmani, Maryam, Saffari, Fereshteh, Domann, Eugen, Zimmermann, Kurt, Langroudi, Ladan, Mansouri, Shahla
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - pharmacology; Antimicrobial agents; Applied Microbiology; Bacteriocins; Biofilms; Caco-2 Cells; Cell culture; Cell walls; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Collagen; Enterococcus; Enterococcus faecalis; Escherichia coli; Fecal microflora; Gastrointestinal Microbiome; Gastrointestinal tract; Gelatinase; Gene frequency; Humans; Infants; Intestinal microflora; Intestine; Microbiology; Microbiota; Nutrition; Organic acids; Probiotics; Protein Science; Sex pheromone; Symbionts; Toxicity; Virulence; Virulence Factors - genetics
• ISSN: 1867-1306; 1867-1314
• DOI: 10.1007/s12602-022-09951-3

Enterococci act as symbionts in human gastrointestinal tract. The present study aimed to evaluate the characteristics of fecal enterococci isolated from infants and adults, and to compare them to the known probiotic bacteria, including lactobacilli species and E. faecalis Symbioflor 1. In total, sporadic distribution of virulence genes was detected among the studied enterococci. Furthermore, the frequency of genes encoding for sex pheromones ( ccf and cob ), collagen adhesion ( ace ), cell wall adhesion ( efaAfs ), and gelatinase ( gelE ) was observed to be significantly higher in those isolates obtained from infants compared to those obtained from adults. Although the ability of biofilm formation was found in all isolates, the strong biofilm formation was observed in enterococci from infants and strong correlation was observed between the capacities to form biofilm and attachment to Caco-2 cells. Cell-free culture supernatant showed some inhibitory effects on indicator strains, which were related to the production of organic acids (against P. aeruginosa and enteropathogenic E. coli ) or both organic acids and proteinaceous antimicrobial agents (against L. monocytogenes and E. faecalis ). Approximately, 79% and 71% of the isolates showed strong inhibitory effects on P. aeruginosa and L. monocytogenes , respectively. Unlike lactobacilli, enterococcal cell-free supernatants had no toxicity on intestinal cells. In conclusion, this study shows that some enterococcal isolates obtained from fecal microbiota have characteristics, which are comparable with the known probiotic bacteria. Therefore, these isolates should be considered to find probiotic candidate. The proteinaceous identity of antimicrobial substances derived from these isolates highlighted the probable contribution of bacteriocins into this issue.