Escherichia coli O157:H7 Eliminasyonu İçin Doğal Antimikrobiyal Bileşenlerin ve Bakteriyofajların Kullanımı
Evran , Şefika
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In recent years, with the development of antibiotic resistance, difficulties have been experienced in the control of pathogenic bacteria. Therefore, new methods need to be examined in the context of the fight against pathogenic bacteria. E. coli O157: H7 is an significant pathogen for humans. In this thesis, the use of natural antimicrobial components and bacteriophages for inhibition of E. coli O157: H7 bacteria and the effect of the combination of these components and bacteriophages on E. coli O157: H7 bacteria were investigated. Phages of E. coli O157: H7 were first isolated. Phenolic extracts were extracted from vegetable products such as grapes, quince and pomegranate and its antibacterial effect on E. coli O157: H7 was investigated. In addition, antimicrobial effect of five different molasses samples and propolis on E. coli O157: H7 were investigated. Antibacterial effect was investigated in both solid and liquid medium. The total phenolic contents of plant extracts and propolis were analyzed, and the total phenolic and hydroxymethyl furfural (HMF) amounts of molasses were determined. HMF and total phenolic values were determined in order to determine some characteristics of the samples. Subsequently, plant extracts, molasses samples and the use of propolis with phages were investigated for inhibition of E. coli O157: H7. In general, the original concentration of molasses samples d and d/2 and d/4 concentrations led to growth of phage plaques, while d/16 concentration did not affect plaque size. High concentrations of grape, quince and pomegranate extracts inhibited phage formation, while low concentrations did not affect phage plaque size. It was observed that the phage titer decreased in the propolis sample. Since the best effect on plaque size was seen in molasses, liquid medium experiments were started to investigate the interaction between phage and molasses. Carob molasses sample and tp3 phage were selected for these experiments. Time-death curve test was performed to understand the effect of phage and phage-molasses only on E. coli O157: H7 inhibition and phage titer. In order to understand the effect of the molasses sample on the phage burst size, a one-stage growth curve was obtained. According to the growth curve results, it was observed that molasses increased phage burst size. The results showed that phage alone worked better and that molasses partially had antiviral effect on phage. Phage susceptibility test was performed to determine the effect of molasses on phage and it was observed that the presence of molasses decreased the phage titer. No complete synergistic effect was observed between phage and molasses.
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