Yazar "Hajikhani, Rasta" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim
    Öğe
    Assessment of some metabolic activities and potential probiotic properties of eight Enterococcus bacteria isolated from white cheese microbiota
    (Springer Science and Business Media Deutschland GmbH, 2021) Hajikhani, Rasta; Önal Darılmaz, Derya; YÜksekdağ, Zehra Nur; Beyatlı, Yavuz
    In the present study, eight strains of Enterococcus spp. were isolated from Turkish and Iranian white cheese test pieces. Enterococcus spp. strains were identified as Enterococcus faecium (6 strains) and E. faecalis (2) with 16S rDNA sequence analysis. All Enterococcus spp. strains showed susceptibility to the most of antibiotics tested in this investigation. The amount of produced acid (0.59–1.17%), hydrogen peroxide (0.65–3.91 µg/ml), and exopolysaccharide (252–362 mg/L) of these strains were determined. These strains possess the ability to inhibit Escherichia coli ATCC 35,218, Salmonella enteritidis ATCC 13,076, and Salmonella typhimurium MU 80. E. faecium RI53 and RI 42 strains were determined as the most resistant to acid (1.86 and 1.56 OD, respectively) and also exhibited high percentage of aggregation (54.1 and 51.7%, respectively). E. faecium RI 42 exhibited a higher growth viability in gastric and intestinal juice. E. faecium RI 53 and RI 42 are determined as optimal potential probiotic candidates for utilization in cheese preparations.
  • Küçük Resim
    Öğe
    Safety and metabolic characteristics of 17 Enterococcus faecium isolates
    (Springer Science and Business Media Deutschland GmbH, 2021) Yüksekdağ, Zehranur; Ahlatçı, Nur Seda; Hajikhani, Rasta; Önal Darılmaz, Derya; Beyatlı, Yavuz
    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 µg 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, efaAfm, cob, ccf, hyl). The isolates did not show gelatinase activity, ?-hemolysis, and biofilm formation. All E. faecium isolates were susceptible to vancomycin, penicillin-G, tetracycline, ampicillin, and chloramphenicol. The efaAfm 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.