Safety and metabolic characteristics of 17 Enterococcus faecium isolates


YÜKSEKDAĞ Z. , Ahlatci N. S. , Hajikhani R., ÖNAL DARILMAZ D., BEYATLI Y.

ARCHIVES OF MICROBIOLOGY, 2021 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Publication Date: 2021
  • Doi Number: 10.1007/s00203-021-02536-8
  • Title of Journal : ARCHIVES OF MICROBIOLOGY
  • Keywords: Enterococcus faecium, Lactic acid, Hydrogen peroxide, Exopolysaccharide, Antibiotic susceptibility, Virulence genes, LACTIC-ACID BACTERIA, VIRULENCE FACTORS, ANTIMICROBIAL RESISTANCE, PROBIOTIC PROPERTIES, BIOFILM FORMATION, TECHNOLOGICAL PROPERTIES, ANTIBACTERIAL ACTIVITY, VANCOMYCIN RESISTANCE, ANTIBIOTIC-RESISTANCE, GENES

Abstract

In the present study, metabolic characteristics, such as lactic acid, hydrogen peroxide, exopolysaccharide (EPS) production, and antimicrobial activities, of 17 Enterococcus faecium isolates from white cheese samples were assessed. In E. faecium isolates, the amount of lactic acid obtained between in MRS medium 0.61-1.22% and in skim milk 0.75-1.08%, and the amount of H2O2 was found between 0.57 and 3.17 mu g mL(-1). In MRS and skim milk, the amount of EPS production was 59-185 mg L-1, 155-255 mg L-1 for isolates, respectively. The antimicrobial activities of E. faecium isolates on eight different pathogenic bacteria were also performed by an agar well diffusion method. The highest inhibition zones 8.60 mm were observed with culture supernatants of RI-71 isolate against Escherichia coli ATCC 35218. The safety of the E. faecium isolates was assessed by determining gelatinase activity, hemolytic activity, the resistance to ten different antibiotics, biofilm forming, and virulence genes (van A, van B, gelE, cylA, cylB, esp, agg, and asa1, efaA(fm), cob, ccf, hyl). The isolates did not show gelatinase activity, beta-hemolysis, and biofilm formation. All E. faecium isolates were susceptible to vancomycin, penicillin-G, tetracycline, ampicillin, and chloramphenicol. The efaA(fm) gene was detected most frequently (94%) followed by cob (82%), van B (59%), and ccf (53%). For enterococci to be recommended as co-starter or probiotic adjunct cultures, it is necessary to determine whether they have virulence genes and resistance to antibiotics.